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    Infectious Disease Control Unit
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Texas Department of State Health Services Report

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Task Force/Recommendations

 

Background

Purpose of the Texas Legionellosis Task Force

In November 1996 a major hospital in San Antonio, TX, notified the Texas Department of State Health Services (DSHS) in Austin about an apparent increase in the number of nosocomial Legionellosis cases in that facility. Staff from the Infectious Disease Epidemiology and Surveillance Branch were asked to assist the hospital in evaluating this potential cluster. During the evaluation of hospital records and practices, other recent nosocomial Legionellosis patients were identified in several other San Antonio area hospitals. The discovery of these cases led to a joint investigation involving the San Antonio Metropolitan Health District, the Texas Department of State Health Services, and the Centers for Disease Control and Prevention in Atlanta, Georgia (CDC). In that investigation it became apparent that the risk of nosocomial Legionellosis in Texas is highly variable and that the method of water treatment in a given community may influence the risk of Legionella bacterial contamination in the hospital setting. A description of the investigation was published [1].

In December 1999 Reyn Archer, MD, then Commissioner of the Texas Department of State Health Services, asked Dennis Perrotta, PhD, the State Epidemiologist, and IDCU staff to convene a task force of Texas physicians, nurses, and public health professionals to develop a Legionellosis control plan for the state of Texas. Task force members are identified in Appendix A. The recommendations contained in this plan are intended to help local health officials respond to reports of legionellosis in hospitals, long-term care facilities (LTCFs), and the community. They are also intended to guide hospitals and LTCFs in the establishment of their Legionellosis control plan.

In June 2000 the State of Maryland Department of Health and Mental Hygiene published a comprehensive report of their Scientific Working Group to Study Legionella in Water Systems in Healthcare Institutions [2]. The Maryland plan was the most comprehensive document published by any state health department on Legionnaires’ disease control issues to date, and recognizing the value of that document and the work it represents, DSHS staff asked for and received permission from the Maryland Department of Health and Mental Hygiene to incorporate elements of their document into the Texas plan. While the DSHS acknowledges the substantial amount of information in the Maryland plan that is included herein, the Texas plan differs significantly from the Maryland document in specific recommendations.

Overview of Legionellosis

Legionella bacteria were first recognized in association with an outbreak of pneumonia in 1976 that occurred among attendees of an American Legion convention in Philadelphia [3]. Since then, more than 39 species and 61 serogroups of Legionella bacteria have been identified [4]. While more than half of these species/serogroups have been associated with human disease [5,6], L. pneumophila, the first Legionella species identified, accounts for approximately 90% of infections, with illness most frequently associated with serogroups 1, 4, and 6 [7].

Legionella can cause Pontiac Fever, an often undiagnosed and generally mild and self-limiting "flu-like" illness [8]. They also cause Legionellosis, a potentially severe bacterial pneumonia that is accompanied by cough, fever, and fatigue [9]. Legionellosis is used to describe both diseases. The incubation period for Legionellosis is usually 2-10 days. Based on studies in several parts of the country, Legionellosis may account for 5-15% of all community-acquired pneumonias [10]. Without appropriate antibiotic therapy, infection can cause serious

complications and even death. Patients with Legionellosis have signs and symptoms that resemble other bacterial pneumonias, and the diagnosis generally cannot be made by a physician in the absence of specialized laboratory testing [11].

Certain populations are clearly at greater risk than others for developing severe Legionella infections [12-15]. The most important host risk factors for developing illness include 1) immunosuppressive therapy (anti-rejection therapy to prevent graft rejection in bone marrow and solid organ transplant patients), 2) chemotherapy for neoplastic disease, current steroid therapy (>20 mg/day for more than 14 days;[16]), and 3) chronic underlying illnesses such as hematologic malignancies or end-stage renal disease. There is a moderately increased risk of illness among the elderly (age > 65 years), smokers, and people with chronic lung disease, diabetes, or congestive heart failure. The disease is extremely rare in children.

Diagnosis

Legionellosis is characterized by fever, myalgias, cough, and pneumonia. It cannot be distinguished clinically or radiographically from pneumonia caused by other agents, and evidence of infection with other respiratory pathogens does not rule out the possibility of concomitant Legionella infection.

Laboratory tests used to diagnose Legionella infection are summarized in Table 1. The definitive method for diagnosis is culture of the organism. Culture requires use of a specialized panel of differential and selective media. Respiratory specimens are plated onto these media (buffered charcoal yeast extract agar [BCYE], BCYE/PVA [contains polymixin B, vancomycin, and anisomycin], and BCYE/PAC [contains polymixin B, anisomycin, and cefamandole]) and incubated at 35-37oC (95-98.6oF) for up to 14 days [3]. The ideal specimens for culture are bronchial washings, bronchial lavages, or bronchial brushings. If a sputum is the only specimen that can be obtained, results are improved if the sample is pretreated with 0.2 M KCl/HCl solution (pH=2.2) for 4 minutes to decrease numbers of endogenous bacteria that can grow on the BCYE agar [17]. In experienced hands, culture results can usually be obtained in 3 to 5 days.

The advent of urine antigen testing in the mid 1990s provided for the first time a simple, rapid means of identifying infected patients. There are currently two FDA-approved rapid antigen detection assays designed to detect Legionella-specific antigens in urine specimens [18-20]. The first is an enzyme-linked immunoassay (EIA) that requires special laboratory instrumentation and takes approximately three hours to perform. The second, which has just recently been introduced, is a rapid antigen card test (a paper chromatography based assay) that requires less than 30 minutes to perform and no instrumentation. Both tests have comparable sensitivity and specificity, but are only capable of detecting L. pneumophila serogroup 1, which accounts for 70-80% of disease.

Direct fluorescent antibody (DFA) staining is another rapid diagnostic test for Legionella species. This technique is much less sensitive than either culture or the urine antigen tests because large numbers of organisms must be present. Colonies grown in culture or respiratory secretions can be used for DFA. Genus-specific antibodies are used to confirm the isolation of Legionella.

Antibody testing of serum, while available, also has significant drawbacks. Chief among these is the need for two serum samples, one drawn shortly after illness onset and a second 3 to 6 weeks later. Diagnosis is confirmed by a fourfold increase in the antibody titer to 1:128 or more. Positive results are not useful for case management. From a practical standpoint, it is also difficult to arrange for collection of a second blood sample from a patient weeks after he or she has recovered from an illness and been discharged from an acute care facility.

Table 1: Laboratory methods for clinical diagnosis of Legionella infection

         

Technique

Sensitivity

Specificity

Processing

Disadvantages

 

 

 

 

 

Culture

80%

100%

3-5 days

Requires specially trained laboratory technicians

 

 

 

 

 

Urinary antigen test

80%

95%

within hours

Only detects L. pneumophila serogroup 1

 

 

 

 

 

Direct fluorescent antibody

33-70%

95-100%

within hours

Sensitivity is low, requires specially trained laboratory technicians

 

 

 

 

 

Antibody Testing (serology)

40-60%

95-100%

2-4 days

Sensitivity is low, requires collection of second blood sample 3-6 weeks after acute specimen collected

                 

Epidemiology

The CDC estimates that between 8,000 and 18,000 cases of Legionellosis occur each year in the United States; from 1995 through 2000, 400 to 600 of these were reported to public health authorities. Nosocomial cases have a higher mortality rate than community-acquired cases (40% compared to 20%)[14]. Nosocomial outbreaks often continue for years before being recognized [18,21]. In a national survey of 192 randomly selected hospitals, 29% reported having at least a single case of nosocomial Legionellosis and 16% reported greater than five cases. Of these surveyed hospitals, 60% had on-site testing capabilities, but only 21% had established routine Legionella testing [22].

Legionellosis became a reportable condition in Texas in July 1984: Both physicians and laboratories are required by law to report confirmed cases of legionellosis to their local health departments. The following CDC case definition is used for reporting purposes [23]:

  • Legionellosis is associated with two clinically [...] distinct illnesses: Legionnaires’ disease, which is characterized by fever, myalgias, cough, and pneumonia and Pontiac fever, a milder illness without pneumonia.
  • Laboratory criteria for diagnosis:
    • Isolation of Legionella from respiratory secretions, lung tissue, pleural fluid, or other normally sterile fluids, or
    • Demonstration of L. pneumophila serogroup 1 antigens in urine by radioimmunoassay or enzyme-linked immunosorbent assay, or
    • Detection of L. pneumophila serogroup 1 in respiratory secretions, lung tissue, or pleural fluid by direct fluorescent antibody testing, or
    • Demonstration of a fourfold or greater rise in the reciprocal immunofluorescence antibody (IFA) titer to > 128 against Legionella pneumophila serogroup 1 between paired acute- and convalescent-phase serum specimens.
  • For nosocomial legionellosis, the following CDC case definitions are used [14]:
    • Confirmed nosocomial case: laboratory-confirmed legionellosis that occurs in a patient who has been hospitalized continuously for > 10 days before the onset of illness.
    • Possible nosocomial case: laboratory-confirmed legionellosis that occurs in a patient 2-9 days after hospital admission.
    • [Note: The incubation for Pontiac fever is shorter than that for Legionnaires' disease; it is 1-3 days.]
    • For the purposes of this document, nosocomial infections shall include those acquired in hospitals, LTCFs, or other medical assisted living facilities.

From 1990-1999 inclusive, there were 227 laboratory-confirmed cases of legionellosis reported to the Texas Department of State Health Services, for an average of 23 cases per year (range 13-32). The most significant obstacle to confirming suspected legionellosis is the difficulty of obtaining convalescent sera. From 1990-1999, the health department received approximately four times as many single-titer results as confirmed results (yearly average of 83 compared to 23). Clearly, physicians suspect legionellosis far more often than they confirm it. A single Legionella antibody titer result is not sufficient to confirm a suspected case of legionellosis.

The Texas Department of State Health Services has investigated three legionellosis outbreaks since 1989, involving from 3 to 20 patients each. However, state and local health departments have been asked to address numerous “pseudo-outbreaks” each year around suspected or feared but unconfirmed cases. Most of these were based on a single elevated Legionella antibody titer.

Environmental Ecology

Legionella is widely distributed in aquatic environments. The bacteria thrive in indoor water systems, even in the presence of usual free (unbound) chlorine residual levels; this is particularly true if water is in a temperature range of 25-42oC (77-108oF), sediment and scaling are present, and the water is relatively stagnant. Growth may be facilitated by the presence of other microorganisms capable of supporting intracellular growth of the organism. Legionella organisms die rapidly at temperatures above 50oC (122oF). A one log reduction (eg, from 1000 to 100) in the number of Legionella organisms is accomplished in 1.4-10.6 minutes at 60oC (140oF), in 1.1-2.6 minutes at 70oC (158oF), and in 0.4-0.7 minutes at 80oC (176oF) [24]. In hospitals and other institutions, Legionella are found primarily in two locations, 1) potable hot water systems (defined as all building plumbing systems that distribute water for direct human contact)[25], and 2) water in cooling towers. In hot water systems, concentrations of the bacterium are highest in biofilms within the system and at openings of water outlets. While data are limited, ingestion/aspiration and aerosolization of potable water from hot water systems are thought to represent the major routes by which the organism is transmitted to patients in nosocomial Legionella cases [26-29]. Exposure to aerosols from cooling towers containing the organism has most often been associated with community outbreaks [30-33], although this route should also be considered for nosocomial cases.

Many, but not all, hospital hot water systems are colonized with Legionella (Table 2). It is hypothesized that the organism is introduced into institutional water distribution systems from public/municipal water systems. Municipal water systems do not routinely screen water for the presence of Legionella. As Legionella is moderately chlorine tolerant, it will survive many standard municipal water treatment protocols. Once present in a hospital hot water system, Legionella organisms are able to survive and multiply, particularly at hot water temperatures kept relatively low to minimize the scald risk for patients [34]. Factors which determine whether a specific hospital water system will be colonized with Legionella are not well understood, but probably include the type of disinfection used, age and condition of the pipes, the degree of scaling and sediment, and the potential for biofilm formation within the system. Methods for obtaining cultures from water systems are not well standardized, and it is clear that results vary widely depending on the methodology used.

Table 2: Hospital surveys for Legionella contamination of water systems (adapted from Yu, 1998 [35])

 
Location

Number of Hospitals

Percent with Legionella

Reference

 

 

 

 
United Kingdom

40

70

HMSO [36]

Quebec

84

68

Alary [37]

Western PA

15

60

Vickers [38]

United Kingdom

69

55

Patterson [39]

Nova Scotia

39

23

Marrie [40]

United Kingdom

17

12

Liu [41]

Texas

15

73

Kool [1]

Temporary elimination or reduction of Legionella colonization in a hot water "ecosystem" is possible, although difficult. Success depends on the design and condition of the system, as well as the remediation methodology used. If a system is old, cleaning and descaling may be an important component of a Legionella control program. As Legionella is killed by temperatures over 50oC (122oF), superheating of water (raising of water temperature above the normal set point for the system) may be efficacious [24]. CDC recommendations call for flushing of the hot water system for a minimum of 30 minutes with the hot water superheated above 60oC (140oF) [42]. While superheating may result in a reduction in system colonization, Legionella is usually not eradicated, and often recolonizes the system within a matter of weeks, necessitating recurrent superheating cycles. As an alternative to superheating, CDC recommends "shock" hyperchlorination (flushing all outlets for at least 5 minutes with greater than 10 mg/liter of chlorine in water)[43,44]. Again, this method may only suppress Legionella, permitting subsequent recolonization. Continuous hyperchlorination has been attempted by several institutions, but has generally been discontinued because of its corrosive effect on plumbing [45]. For example, three years after implementation of hyperchlorination at a University of Iowa hospital, the incidence of pipe leaks was 30 times the rate before chlorination.

Success with long-term disinfection has been obtained with continuous copper-silver ionization techniques, though there are reports of such a system losing efficacy over time [46-52]. UV light systems may be useful for localized disinfection, but there are no distal, residual effects [53,54]. A new hospital at the University of Virginia built in 1989 had a UV light disinfection system installed on the municipal water intake upon completion. Despite having had substantial problems with Legionella in its old hospital building, the potable hot water in this new building has remained consistently culture-negative for Legionella (with no nosocomial Legionella cases), suggesting that it is possible to prevent initial colonization of newly constructed hot water systems [55]. There are also now intriguing data suggesting that use of monochloramine as a disinfectant in municipal and hospital systems (rather than the more traditional free chlorine) is effective in eradicating Legionella [56,57]. In a recent study in Texas [1], all 11 hospitals on municipal water systems using free chlorine for disinfection had Legionella in their water systems; in contrast, the 4 hospitals on municipal water systems using monochloramine for disinfection had water systems that were culture-negative for Legionella (and had no cases of nosocomial Legionella infection).

A Maryland hospital recently reported installation of a monochloramine system in an administration building of a hospital that had ongoing problems with Legionella in patient care areas; placement of the system resulted in a significant decrease in the Legionella counts in the building’s potable hot water system [58]. Further details regarding methods for minimizing the risk of Legionella in building water systems (including cooling towers and other water sources) can be obtained from the recent guidelines published by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE)[59].

While it is well recognized that Legionella can colonize a hospital hot water system, the link between specific levels of colonization and risk of nosocomial Legionella infection remains uncertain. In a longitudinal study at the Pittsburgh Veterans Affairs hospital published in 1983, cases of nosocomial Legionella infection were most likely to occur when more than 30% of 10 selected distal sites in the hospital water system were culture-positive for Legionella [60]. Based on these findings, the Allegheny County, Pennsylvania, health department established guidelines ([61], www.legionella.org/ACHD_guideline.htm) under which hospitals are advised to routinely culture their water systems for Legionella, and initiate control efforts for Legionella in the water system when >30% of distal sites are culture-positive for the organism. Since these guidelines were put in place in 1992, the percent of total reported Legionella infections in Allegheny County, PA, that are hospital-acquired has dropped from 50% (23 of 46 cases) to 13% (4 of 30 cases)[62]. This 30% of distal sites "action level," while demonstrating utility in controlling nosocomial Legionella infections in the Pittsburgh area, has not been tested in studies in other geographic areas. In the recent Texas study, there was a suggestion that risk of nosocomial illness correlated with the proportion of samples from which Legionella was recovered at each institution [1].

Further, there do not appear to be sufficient data to substantiate use of quantitative Legionella counts (i.e., actual counting of Legionella bacterial colonies on a plate, rather than simply reporting a culture as positive or negative) to predict risk of illness. It is also clear that quantitative values can vary dramatically depending on sampling and culture techniques.

Existing Guidelines for Prevention

In 1994 the CDC proposed guidelines to prevent and control nosocomial pneumonia (including Legionellosis); these guidelines were updated in 1997 [14;www.cdc.gov/ncidod/diseases/hip/pneumonia/2_legion.htm]. The guidelines advocate active surveillance and good casefinding strategies in hospitals, including establishment of appropriate diagnostic capabilities for Legionella. CDC guidelines/recommendations do not advocate routine culturing of water systems for Legionella, noting the overall high rate of colonization of hospital water systems with the bacterium, and citing the lack of data to substantiate any one "action level" for positive cultures. CDC investigators have also expressed concern that negative culture results will give physicians a "false sense of security" that Legionella cases will not occur in their facility. Instead, CDC recommends that environmental sampling be conducted when nosocomial Legionella cases are identified in hospitals with high risk patients (see Hospital Infection Control Practices Advisory Committee [HICPAC] recommendations [15]). Decontamination is recommended if infections are traced to a specific source (such as the water system), with the effectiveness of decontamination monitored by sampling every 2 weeks for 3 months and, if negative, sampling monthly for another 3 months. As CDC investigators do not feel that a "safe" level of Legionella in a water system can be determined, monitoring and decontamination efforts should be continued until cultures are negative. CDC guidelines also note the need for routinely maintaining cooling towers (also see ASHRAE guidelines [59]); and using only sterile water for the filling and terminal rinsing of nebulization devices. More recently CDC has published draft guidelines, Prevention of Opportunistic Infections Among Bone Marrow Transplant Recipients, that recommend periodic routine culturing for Legionella from a unit’s potable water supply as part of an overall strategy to prevent Legionnaires’ disease in transplant patients. These guidelines further recommend that the goal of environmental surveillance for Legionella in transplant units should be to maintain water systems with NO detectable organisms.

The guidelines developed for control of Legionellosis by the State of Maryland resemble those of the CDC in that they recommend hospital personnel conduct active surveillance and casefinding, have ready access to appropriate tests for diagnosis, and investigate all nosocomial cases [2;www.dhmh.state.md.us/html/legionella.htm]. The Maryland guidelines differ from those of CDC, however, in that they recommend routine culturing of water distribution systems within hospitals. The frequency of culturing is to be determined by an assessment of risk factors for Legionnaires’ disease, including water system design and condition, patient population susceptibility, and past history of Legionella in patients or the water system. In the Maryland guidelines, remediation is triggered by the identification of a nosocomial case of Legionnaires’ disease; however, the goal of complete elimination of Legionella is generally not recommended.

Like the State of Maryland recommendations and in contrast to the approach taken by CDC for all hospitals, Allegheny County, PA, has implemented a control strategy for nosocomial Legionella infection that incorporates regular environmental sampling ([61], www.legionella.org/ACHD_guideline.htm). The Allegheny County document recommends that all hospitals perform yearly environmental surveys that include water sample cultures. The specific recommendations are as follows:

"If transplants are performed, then surveys should be performed more often. An environmental survey should consist of: a) all hot water tanks, b) distal sites (faucets or showerheads). If hospital beds are less than 500, a minimum of 10 distal sites should be surveyed. If bed size is greater than 500, 2 distal sites per 100 beds are recommended. The distal sites [samples] should be taken from units housing patients at higher risk for acquiring Legionnaires’ disease (COPD [chronic obstructive pulmonary disease], immunosuppression, transplant)."

The Allegheny County, PA, guidelines also emphasize the need for good surveillance for nosocomial legionellosis, and the associated need for optimal diagnostic capabilities for Legionella in hospitals. Regardless of environmental findings, remediation efforts are triggered by identification of a nosocomial case. These guidelines recognize that total elimination of Legionella from a water system may not be possible, or necessary; the goal is to reduce Legionella levels to a point (<30% of distal sites positive) where risk of nosocomial Legionella infection is felt to be minimized.

In hospitals in which nosocomial cases are identified, there may be some benefit to limiting exposure of immunocompromised patients to potential sources of infection, pending reduction or elimination of Legionella colonization of the water system. It has been suggested that this be accomplished by prohibiting patient showers and using only sterile water for oral consumption [14].

Texas Recommendations for Acute Care Hospitals

In preparing recommendations, the Texas Legionellosis Task Force carefully considered the work of the Maryland Scientific Working Group, the published guidelines of the CDC, and the opinions of other prominent researchers in the field. The recommendations presented below reflect the expert opinion of the Texas Task Force, drawing on available published data and the expertise and experience of Task Force members. Many of the recommendations are intended for physicians and hospitals, because the people at greatest risk of acquiring legionellosis are immunocompromised and/or chronically and seriously ill patients who are hospitalized or are outpatients under the care of a physician. The Task Force also made recommendations for nursing homes and other LTCFs that serve as permanent residences for medically fragile individuals. Finally, the Task Force developed some guidelines to assist health departments and physicians address sporadic, community-acquired cases.

The Task Force recognizes that no single template can serve the needs of all types of facilities, and strongly supports an approach that allows institutions to individualize their legionellosis control plans based on the history of their institution; the matrix of environmental factors, engineering issues, and patient populations served by the institution; and the resources the institution has available to address these concerns. The Task Force does intend for each institution to consider the factors that may contribute to legionellosis transmission and diagnosis in their context and to develop a control plan or plan of action that increases physician awareness of the disease, increases the diagnostic capability of that institution, and enhances the institution’s ability to prevent disease.

Each hospital should form a team of representatives from various departments such as infection control, engineering and maintenance, risk management, employee health, administration, and housekeeping to prevent and control legionellosis. The team should develop and write a legionellosis control plan. The team shall be led by a hospital epidemiologist or an infection control professional. This operational plan should encompass several components including: 1) surveillance strategies, 2) whether environmental culturing is recommended, 3) remediation strategies (if and when necessary), and 4) reporting procedures.

Diagnostic Capacity

I. Differential: Clinicians should consider Legionella species in their differential diagnosis for both nosocomial and community-acquired pneumonia. Appropriate diagnostic specimens should be obtained before initiating treatment.

II. Urine Antigen: All acute-care hospitals should either provide Legionella urinary antigen testing in-house, or contract with another laboratory that can report test results within 48 hours.

III.Cultures: All hospitals that routinely perform and care for patients with solid organ and/or bone marrow transplants should have the ability to perform Legionella culture on site. All others should have a mechanism in place that allows them to submit primary specimens for Legionella cultures to a microbiology laboratory within 24 hours of specimen collection.

IV. DSHS as Reference: The DSHS laboratory serves as a secondary reference laboratory for Legionella, with the capability to serotype, speciate, and characterize isolates on a molecular basis. Specimens from possible and definite nosocomial cases should be forwarded to the DSHS.

Surveillance

I. Passive Case Detection

A. A hospital laboratory should notify the infection control practitioner at the hospital within one day of positive results from a Legionella culture, urine antigen test, direct fluorescent antibody test, or a paired serum antibody test (see case definition for legionellosis).

B. If a patient with laboratory evidence of legionellosis has an illness clinically compatible with legionellosis (Legionnaires' disease or Pontiac fever), then the patient has confirmed Legionnaires' disease or Pontiac fever.

C. Confirmed Legionnaires' disease or Pontiac fever cases should be further investigated to determine whether they meet the case definition for nosocomial illness (see case definition for nosocomial legionellosis). A thorough epidemiologic and environmental investigation should be conducted to determine the likely environmental sources. Hospitals that need assistance with an investigation should call their local health department.

D. Confirmed cases of Legionnaires' disease or Pontiac fever should be reported to the local health department (800-705-8868) as “definitely nosocomial,” "possibly nosocomial,” or “not nosocomial” cases within one week of confirmed diagnosis. The report should be submitted on DSHS IDCU Form 5, 02/02; [Form (PDF PDF File: 31.9KB)] to the local health department. The local health department should also report to DSHS within one week of confirmed diagnosis.

E. Outbreaks (defined as two or more institutionally linked cases within the same 6-month period) must be reported immediately to the local health department at 1-800-705-8868.

II. Active Case Detection

When a hospital has a possible or definite nosocomial case, active surveillance must be implemented.

A. Test specimens from patients with pneumonia: Institutions should develop “in-house” legionellosis case-finding strategies. This may include algorithms recommending that the following tests be performed on specimens from high risk patients with pneumonia: 1) culturing of sputa, 2) antigen testing of urine, and 3) culturing and/or direct fluorescent antibody testing of bronchoscopy specimens.

B. Evaluate sputa and x-rays: At a minimum, active surveillance should include daily review of all sputum cultures and chest x-rays. It should include daily review of newly diagnosed pneumonia cases. Once implemented in response to a possible or definite case, active surveillance should continue for at least six months.

Environmental Testing

Environmental testing, in the context of legionellosis, is the sampling of water and plumbing structures of a facility's water distribution system. The Texas Task Force discussed the role of environmental testing as a surveillance measure and investigational tool at great length. There are currently two different views in the United States on the role of environmental testing. One group holds that environmental testing should only proceed once an outbreak or definite transmission has been identified. Another group proposes that all hospitals routinely culture for environmental Legionella. Adoption of the first position, as done by the CDC, could place certain patient populations at increased risk for acquiring Legionellosis; the potential risk to such patients can only be ascertained by environmental testing. Recent research in Texas has shown that there are wide disparities between facilities’ water systems in Legionella colonization [1]. Adoption of the second position, as done by the Allegheny County Health Department and the State of Maryland, commits large numbers of facilities to regular investments of resources that may be disproportionate to the risk involved and in fact may damage the infection control capacity of a given facility by diverting staff time and resources away from other, potentially more pressing, infection control concerns. Drawing on elements from both the CDC position and the position outlined in the report produced by the Scientific Working Group in the State of Maryland, the Texas Legionellosis Task Force developed the following recommendations for healthcare facilities.

I. Assessment of Legionellosis Risk and Criteria for Environmental (Water Distribution System) Testing

All healthcare facilities should, in implementing their legionellosis control plan, assess their risk of legionellosis transmission. Each facility should evaluate environmental, engineering, and patient population factors to determine whether there is a reasonable potential for nosocomial transmission. Baseline water distribution system cultures should be performed if the results of the assessment indicate the facility has a significant risk of legionellosis transmission.

Factors that affectthe risk of nosocomial transmissionin a given facility are as follows:

A. Environmental factors

1. Water chlorination. Recent research [1,57,58] suggests that how the water is treated in a given community can influence Legionella colonization of hospital water systems. Water sources that provide low levels of free chlorine as a residual disinfectant may be at increased risk when compared with water sources that use monochloramine as the chemical residual disinfectant. While this issue needs further study, hospital staff should work with their water supply agency to determine how the water from the municipal supply is treated.

2. Temperature. Legionella bacteria are thermophilic and grow best between 25-42oC (77-108oF). If water is stored in tanks in this temperature range or delivered to patient care areas at a temperature within this range, there is a reasonable risk that Legionella species will be living in the distribution system.

B. Engineering factors: The following water system characteristics have been associated with the growth of Legionella:

1. Vertical configuration (eg, multistory building) [64]

2. Dead legs [21,64 ]

3. Water heaters arranged in parallel [64]

4. Dead space at the bottom of the heaters [64]

5. Silicone-based rubber plumbing products [64]

6. Water softeners [21]

7. Aerators or shower heads in high risk patient areas that aren't cleaned or replaced regularly (association is suspect but plausible)[61]

C. Patient mix: The following patient populations are all at increased risk for legionellosis, and any facility that treats these patients is at increased risk for disease to occur. Immunocompromised employees may also be at increased risk.

1. Solid organ transplant patients

2. Bone marrow transplant patients

3. Patients with cancer undergoing chemotherapy

4. Patients diagnosed with chronic obstructive pulmonary disease

D. Prior history: A prior history of either of the following may increase the risk of transmission:

1. History of nosocomial legionellosis identified among patients

2. History of positive water cultures from the potable water system and outlets or cooling towers

The Task Force recommends that each facility consider these factors in determining whether there is an increased risk of nosocomial transmission. An example of how such a determination may be made is as follows: any facility located in a community where free chlorine is used as a residual disinfectant, that is a multistory facility with multiple water distribution systems, where hot water is stored at 51oC (124°F) and delivered to patient care areas at no greater than 43oC (110°F), with patients receiving bone marrow or solid organ transplants or cancer patients undergoing chemotherapy present, would be considered a facility that is at increased risk for nosocomial transmission. Such a facility should conduct a baseline environmental assessment, including Legionella tests of water samples from water distribution endpoints, and maintain these data on file in the infection control program office and the facility engineer’s office. If, however, the facility is a one story rehabilitation hospital with a limited number of beds and a simple plumbing design, with no dead legs in the system, in a community where monochloramine is used as a residual chemical disinfectant, and no immunosuppressed patients are present, the factors increasing the facility’s risk for transmission would not be present and there would be no recommendation for an environmental assessment at this time.

II. Procedures for Environmental (Water Distribution System) Testing

A. Water distribution system culturing should only be done after one of the following criteria are met:

1. baseline assessment of risk indicates that there is a significant risk of nosocomial transmission

2. there are one or more definite nosocomial cases or two or more possible nosocomial cases

3. remediation has been completed

B. Water distribution system testing should be conducted according to a standard protocol.

1. Refer to Appendix C for specific procedures to use when conducting baseline water distribution system testing and any follow-up testing required by the infection control committee.

2. The Legionella control team should be involved in designing the testing protocol for the facility.

3. The Legionella control team should contract with firms experienced in obtaining specimens for water distribution system culturing of Legionella.

C. Legionella cultures should be qualitative and not quantitative.

D. Serotyping and species identification should be included in the results; hospitals unable to speciate or serotype should send samples to a reference laboratory.

E. When cultures of the water distribution system yield Legionella, the hospital's physicians should be informed to heighten awareness of Legionella as a potential cause of nosocomial pneumonia.

In keeping with the spirit of the State of Maryland Report of the Scientific Working Group and the Allegheny County, PA, recommendations, the intent of the Texas Task Force is not to insist that hospitals must have culture-negative water systems; it is recognized that persistence of Legionella in many instances will be inevitable, and may be of minimal significance from a public health standpoint. All hospitals are expected to maintain good surveillance for nosocomial Legionella cases; identification of a nosocomial case should be a clear indication that further efforts must be made to reduce Legionella colonization of the water supply. Hospitals that do not have the infection control expertise to interpret data should work with the local health department, and may need to retain the services of an expert in this field. However, except in special circumstances (such as an outbreak), water distribution system culture results should not be routinely reported to the health department.

Prevention

Prevention strategies for Legionella pneumonia should be developed and implemented by all acute-care hospitals in Texas as part of each facility’s legionellosis control plan.

I. Primary Prevention

A. Prevention of Legionellosis in Hospitals with No Identified Cases and in Those with No Testing or Negative Baseline Water Distribution System Testing

1. Education: Educate (a) physicians to heighten their suspicion for cases of nosocomial legionellosis and to use appropriate methods for its diagnosis, and (b) patient-care, infection-control, and engineering personnel about measures to control nosocomial legionellosis.

2. Equipment cleanliness

a. Nebulizers and other semicritical respiratory care equipment should be cleaned with sterile water.

b. Enteral tubes should be flushed with sterile water and enteral feedings should be diluted with sterile water [26,27].

3. Facility and physical plant control measures

a. Cooling towers should be designed and constructed so that tower drift is directed away from the hospital’s air intake system and the volume or aerosol drift is minimized. For all operational cooling towers, hospitals should 1) install drift eliminators, 2) use a biocide regularly, 3) maintain towers according to manufacturers recommendations, and 4) keep adequate maintenance records.

b. Units with high-risk patients should not use large volume humidifiers that create aerosols unless they are treated with a high level disinfectant daily.

B. Prevention of Legionellosis in Hospitals with No Identified Cases but with Positive Baseline Water Distribution System Testing (>30% Distal Sites Culture-Positive for Legionella)

1. One long-term study has documented the occurrence of Legionellosis cases in a facility when >30% of distal sites test positive for Legionella, and no cases of the disease when fewer sites test positive [60].

2. Enhanced surveillance

a. Legionella testing should be conducted for 60 days for all nosocomial pneumonia cases that occur two or more days after hospitalization.

b. The availability of laboratory tests for Legionella should be assessed; in the presence of one definite case, new suspect cases should have cultures performed in addition to any rapid tests.

c. Recent pneumonia cases should be reviewed for possible diagnosis as legionellosis. Collect urine specimens on nosocomial pneumonia cases that occurred within the last 60 days and test them with a Legionella urine antigen test, when appropriate.

d. The possibility of hospital-acquired cases among employees should be considered.

e. Cultures of water systems and other potential sources (of Legionella) should be conducted.

f. Case-control studies should be initiated, if appropriate.

3. Remediation: Remediation efforts should be initiated immediately to reduce levels of Legionella colonization in the hospital water system. Approaches to remediation may differ from institution to institution, and should be developed in consultation with engineers or public health officials familiar with Legionella control programs. The ASHRAE guidelines [59] are a reference source for approaches to Legionella control within water systems.

a. Potential remediation efforts include

i. Superheating of water

ii. Hyperchlorination

iii. Copper-Silver ionization

iv. Monochloramine treatment

v. Ultraviolet treatment

b. Where practicable, the following engineering measures should be incorporated into the design and operation of the water system:

i. Instantaneous or semiinstantaneous water heaters should be used instead of tanks. If tanks are used, horizontal tanks are preferred over vertical tanks, and steps should be taken to maintain adequate circulation to minimize cool spots within tanks. Hot water system recirculation pumps should run continuously.

ii. For optimal control of Legionella bacteria, hot water should be generated or stored at or above 60oC (140oF) and reduced to 50oC (122oF) for distribution.

iii. Installation of fail-safe thermostatic mixing valves and pressure independent mixing valves will permit maintaining a higher temperature in the water distribution system while minimizing the risk of scalding.

iv. The design should eliminate "dead legs" and other areas of stagnant water. Standby pumps and piping connections should be cycled regularly. The hot water recirculating system should be installed to serve the fixture farthest from supply.

v. Studies indicate that copper is the most resistant of piping materials for Legionella colonization. Natural rubber gaskets should be avoided.

vi. Careful attention must be paid to the materials and workmanship of pipe insulation. This will help keep hot water pipes hot, and cold water pipes cold.

vii. The water storage and distribution systems should be cleaned and descaled where appropriate.

(Notes: Recommendations for immediate remediation have been previously published by the CDC in the Guidelines for Prevention of Nosocomial Pneumonia [14]; and are covered in the ASHRAE [59] and Allegheny County guidelines [61]. Development of long-term remediation plans will require consultation with experts in this field. The CDC position that remediation efforts should be continued until all environmental cultures are negative may be unrealistic. Depending on the risk profile of the facility, a significant reduction in the number of colonized distal sites may be an acceptable endpoint.)

4. Protection of high risk patients: Consideration of other methods to limit exposure of high risk patients to potentially contaminated water sources, pending successful reduction in levels of Legionella colonization within the hospital water system include

a. possible restrictions on showering.

b. consider restrictions on use of potable hot water: shift to using sterile water for bathing, drinking, oral hygiene, wound care, and dilution of drinks and G-tube feedings.

II. Secondary Prevention: Prevention of Legionellosis in Hospitals with Identified Cases

Identification of one definite or two possible nosocomial Legionella cases within a 6 month period should initiate the preventive measures described in IB above (Prevention of legionellosis in hospitals with no identified cases but with positive baseline water distribution system testing [>30% distal sites culture positive for Legionella]).

Table: Comparison of Legionnaires' Disease Control Plans - See Appendix D

Texas Recommendations for Long-Term Care Facilities

Nursing homes, other LTCFs, and other medical assisted living facilities pose a unique set of challenges from both the infection control and public health perspectives. Such facilities are not acute care hospitals, and the residents of these facilities are in some ways more similar to community residents than to patients requiring acute care in the hospital setting. At the same time, residents of LTCFs are typically medically fragile, though stable, individuals who may have chronic health conditions that do increase their risk for acquiring Legionnaires' disease if exposed. As such, residents of LTCFs represent a population whose public health needs merit consideration.

For nosocomial legionellosis, the following CDC case definitions are used [14]:

Confirmed nosocomial case: laboratory-confirmed legionellosis that occurs in a patient who has been hospitalized [or otherwise institutionalized] continuously for > 10 days before the onset of illness.

Possible nosocomial case: laboratory-confirmed legionellosis that occurs in a patient 2-9 days after hospital [or other institutional] admission.

[Note: The incubation for Pontiac fever is shorter than for Legionnaires' disease; it is 1-3 days.]

For the purposes of this document, nosocomial infections shall include those acquired in hospitals, LTCFs, or other medical assisted living facilities.

Each LTCF should have a legionellosis control plan. This operational plan should address surveillance and reporting strategies, and when environmental (water distribution system) testing and remediation are necessary. Facility staff should be aware of the water treatment procedures used in the community. Water sources that do not use any residual chemical disinfection or use free chlorine as a residual disinfectant may be at increased risk when compared with water sources that use monochloramine as the chemical residual disinfectant [1,57,58].

Diagnostic Capacity

I. Differential: Clinicians should consider Legionella species in their differential diagnosis for nosocomial pneumonia.

II. Urine Antigen: All LTCFs should provide Legionella urinary antigen testing either in-house, or contract with another laboratory that can report test results within 48 hours.

III.Cultures: All LTCFs should have a mechanism in place that allows them to submit primary specimens for Legionella cultures to a microbiology laboratory within 48 hours of specimen collection.

IV. DSHS as Reference Laboratory: The DSHS laboratory serves as a secondary reference laboratory for Legionella, with the capability to serotype, speciate, and characterize isolates on a molecular basis. Specimens from possible and definite nosocomial cases should be forwarded to the DSHS.

Surveillance

I. Passive Case Detection

If a resident of the LTCF is diagnosed with legionellosis, either while residing in the facility or within 9 days of transfer to an acute care hospital for pneumonia, the case should be investigated in a manner similar to the way cases are investigated in the hospital setting. Any resident confirmed to have Legionella pneumonia who has resided in the LTCF for > 10 days prior to their onset of pneumonia should be considered a nosocomial case for that LTCF. Any resident in a LTCF who develops confirmed Legionella pneumonia from 2 through 9 days after admission should be considered potentially nosocomial to that LTCF. Any patient transferred to the LTCF who develops confirmed Legionella pneumonia from 2 through 9 days after admission should be considered potentially nosocomial to both the receiving and transferring facilities. The transferring facility should be notified of such cases.

Confirmed cases of legionellosis should be reported to the local health department (800-705-8868) as “definitely nosocomial,” or "possibly nosocomial,” or “not nosocomial” cases within one week of confirmed diagnosis. The report should be submitted on DSHS IDCU Form 5, 02/02; [Form (PDF PDF File: 31.9KB)] to the local health department. The local health department should also report to DSHS within one week of confirmed diagnosis. For confirmed cases, the local health department should conduct a site assessment to identify potentially high risk environmental factors.

Outbreaks (defined as two or more institutionally linked cases or possible cases within the same 6-month period) must be reported immediately to the local health department at 1-800-705-8868.

II. Active Case Detection

Once a possible nosocomial case is identified in a LTCF, increased surveillance should be implemented. At a minimum, this should include increased surveillance for pneumonia cases and the collection of clinical specimens (i.e. urine for antigen testing) to determine the etiology of all cases of pneumonia in any resident. Enhanced surveillance should continue for at least 6 months.

Environmental Testing

Environmental testing, in the context of legionellosis, is the sampling of water and plumbing structures of a facility's water distribution system. The Texas Task Force does not recommend baseline environmental testing for LTCFs.

Environmental testing should be conducted whenever there are one or more definite nosocomial cases or two or more possible nosocomial cases. Patients who are confirmed as cases are definitely nosocomial if they have not left the facility within the previous 10 days.

Procedures for Environmental (Water Distribution System) Testing

I. Environmental Testing Should Be Conducted According to a Standard Protocol.

A. Refer to Appendix C.

Appendix C contains specific procedures to use when conducting baseline environmental testing and any follow-up testing required by the infection control committee.

B. The Legionella Control Team Should Be Involved in Designing the Testing Protocol for The Facility.

C. Contract with Firms Experienced in Obtaining Specimens for Environmental Culturing of Legionella.

II. Legionella Cultures Should Be Qualitative and Not Quantitative.

III.Serotyping and Species Identification Should Be Included in the Results; Hospitals Unable to Speciate Should Send Samples to a Reference Laboratory.

IV. The Results of Any Environmental Cultures Obtained Should Be Provided to Hospital Physicians in Order to Heighten Awareness of the Possibility of Legionella as a Cause for Nosocomial Pneumonia.

Prevention

Prevention strategies for Legionella pneumonia should be developed and implemented by all LTCFs in Texas as part of their legionellosis control plan.

I. Primary Prevention: Prevention of Legionellosis in LTCFs with No Identified Cases

A. Education

The infection control staff should educate (a) clinicians to heighten their suspicion for cases of nosocomial Legionnaires' disease and to use appropriate methods for its diagnosis, and (b) patient-care and engineering personnel about measures to control nosocomial legionellosis.

B. Equipment Cleanliness

1. Nebulizers and other semicritical respiratory care equipment should be cleaned with sterile water.

2. Enteral tubes should be flushed with sterile water and enteral feedings should be diluted with sterile water [26,27].

C. Facility and Physical Plant Control Measures

1. Cooling towers should be designed and constructed so that tower drift is directed away from the facility’s air intake system and the volume of aerosol drift is minimized. For all operational cooling towers, hospitals should 1) install drift eliminators, 2) use a biocide regularly, 3) maintain towers according to manufacturers recommendations, and 4) keep adequate maintenance records.

2. Units with high-risk patients should not use large volume humidifiers that create aerosols unless they are treated with a high level disinfectant daily. High risk illness includes a) immunosuppressive therapy (anti-rejection therapy to prevent graft rejection in bone marrow and solid organ transplant patients), b) chemotherapy for neoplastic disease, current steroid therapy (>20 mg/day for more than 14 days;[16]), and c) chronic underlying illnesses such as hematologic malignancies or end-stage renal disease.

II. Secondary Prevention: Prevention of Legionellosis in LTCFs with Identified Cases

The following preventive measures should be initiated immediately whenever one definite or two possible nosocomial Legionella cases occurring within a 6 month period are identified:

A. Enhanced Surveillance

1. Legionella testing should be conducted for 60 days for all nosocomial pneumonia cases that occur two or more days after institutionalization.

2. The availability of laboratory tests for Legionella should be assessed; in the presence of one definite case, clinicians should order cultures performed on new suspect cases in addition to any rapid tests.

3. Recent pneumonia cases should be reviewed for possible diagnosis as legionellosis. Collect urine specimens on nosocomial pneumonia cases that occurred within the last 60 days and test them with a Legionella urine antigen test, when appropriate.

4. The possibility of facility-acquired cases among employees should be considered.

5. Environmental surveillance, including cultures of water systems and sources, should be conducted.

6. Consult with the local health department regarding further investigation.

B. Remediation

Remediation efforts should be initiated immediately to reduce levels of Legionella colonization in the facility's water system. Approaches to remediation may differ from institution to institution, and should be developed in consultation with engineers familiar with Legionella control programs. The ASHRAE guidelines [59] are a reference source for approaches to Legionella control within water systems.

1. Potential remediation efforts include

a. Superheating of water

b. Hyperchlorination

c. Copper-Silver ionization

d. Monochloramine treatment

e. Ultraviolet treatment

2. Where practicable, the following engineering measures should be incorporated into the design and operation of the water system:

a. Instantaneous or semiinstantaneous water heaters should be used instead of tanks. If tanks are used, horizontal tanks are preferred over vertical tanks, and steps should be taken to maintain adequate circulation to minimize cool spots within tanks. Hot water system recirculation pumps should run continuously.

b. For optimal control of Legionella bacteria, hot water should be generated or stored at 60oC (140oF) and reduced to 50oC (122oF) for distribution.

c. Installation of fail-safe thermostatic mixing valves and pressure independent mixing valves will permit maintaining a higher temperature in the water distribution system while minimizing the risk of scalding.

d. The design should eliminate "dead legs" and other areas of stagnant water. Standby pumps and piping connections should be cycled regularly. The hot water recirculating system should be installed to serve the fixture farthest from supply.

e. Studies indicate that copper is the most resistant of piping materials for Legionella colonization. Natural rubber gaskets should be avoided.

f. Careful attention must be paid to the materials and workmanship of pipe insulation. This will help keep hot water pipes hot, and cold water pipes cold.

(Notes: Recommendations for immediate remediation have been previously published by the CDC in the Guidelines for Prevention of Nosocomial Pneumonia [14]; and are covered in the ASHRAE [59] and Allegheny County guidelines [61]. Development of long-term remediation plans will require consultation with experts in this field. The CDC position that remediation efforts should be continued until all environmental cultures are negative may be unrealistic. Depending on the risk profile of the facility, a significant reduction in the number of colonized distal sites may be an acceptable endpoint.)

C. Protection of High Risk Patients

Consideration of other methods to limit exposure of high risk patients to potentially contaminated water sources, pending successful reduction in levels of Legionella colonization within the facility's water system include

1. possible restrictions on showering.

2. consideration of restrictions on use of potable hot water, with a shift to use of sterile water for bathing, drinking, oral hygiene, wound care, and dilution of drinks and G-tube feedings.

Texas Recommendations for Sporadic Community-Acquired Cases

Only 15-20% of legionellosis cases reported to the CDC have occurred in outbreaks [13]. Most (80-85%) cases of Legionnaires' disease occur as sporadic, community-acquired pneumonias. Sporadic legionellosis is extremely difficult to study and determining the correct public health response to a single case is difficult. People are exposed to hundreds of potential water aerosols each week, and studies have suggested that, at least in a hospital situation, aspiration of potable drinking water may be an important route of transmission [26]. Most patients with Legionella infection have multiple potential exposures (workplace, hotel, or other public space) during their 10-day incubation period; it is almost always impossible to conduct a meaningful investigation around a single sporadic case.

A cluster of legionellosis cases with a common exposure can involve both Legionnaires' disease and Pontiac fever [65]. The Task Force therefore recommends that investigating health departments be alert to this possibility. Questions regarding ill contacts of Legionnaires' diseases case patients should not be limited to persons with symptoms of pneumonia.

The Task Force recommends the following guidelines to assist health department staff in responding appropriately to such events and to educate physicians on the importance of correctly confirming the diagnosis before informing a patient that they have Legionellosis. The health department should disseminate information regarding Legionellosis to physicians [eg, 66].

Diagnosis

When a sporadic case of Legionellosis is diagnosed, the first priority is to confirm the diagnosis. First, ensure that the patient has a compatible clinical syndrome. A patient must have x-ray confirmed pneumonia. Second, the case must be laboratory-confirmed. A positive culture or positive urine antigen test is necessary for a confirmed diagnosis of the disease. Single total antibody titers are not diagnostic and should never be used to confirm Legionellosis.

Surveillance

I. Passive Case Detection and Follow-up

Cases of confirmed Legionellosis reported by physicians or laboratories should be investigated by the local health department. (Confirmed cases should be reported to the local health department; 800-705-8868.) The patient or patient’s contacts should be interviewed to ascertain all potential exposures to water or water aerosols at home, at work, and to obtain a travel history for the patient during the 10 days prior to onset with pneumonia symptoms. DSHS IDCU Form 5, 02/02; [Form (PDF PDF File: 31.9KB)], including the exposure information, should be sent to the Public Health Region office and the Texas Department of State Health Services promptly.

Family members, coworkers, and other contacts of the patient should be educated about Legionellosis. Particularly emphasize that healthy children and adults have a low risk of acquiring the disease and the disease is not transmitted person-to-person. Remind contacts of the disease symptoms (nonproductive cough, high fever, anorexia, malaise, headache, myalgias, abdominal pain and diarrhea). Remind contacts that people who are immunosuppressed, organ transplant or bone marrow transplant recipients, cancer patients undergoing chemotherapy, or patients with chronic obstructive pulmonary disease are at increased risk. Anyone experiencing symptoms should be evaluated by a physician. A fact sheet, entitled “Legionellosis: Legionnaires’ disease and Pontiac fever,” is attached as Appendix E. Local clinicians should be reminded to report patients who fit the case definitions.

II. Active Surveillance and Epidemiologic Investigation

If the local health department determines that two or more confirmed cases share a common reported exposure during any 6 month period, an epidemiologic investigation should be initiated. The investigation should include:

A. Case Finding

The local health department should promptly initiate case finding in the community.

1. Inform primary care physicians, emergency room staff, and radiologists in the potential outbreak area and any other locations necessary of the following:

a. that there is a cluster of legionellosis cases.

b. how a case of legionellosis is diagnosed.

c. reporting requirements.

2. Contact local hospital infection control staff and emergency room staff to determine whether they have observed an increase in community-acquired pneumonia patients admitted to the facility.

3. Cultures, or sera, if remaining, should be requested to be sent to the public health laboratory and held appropriately.

B. Investigation

If there are 2 or more cases, interview patients or their proxies to learn more about their pertinent exposures.

C. Information Dissemination

Results of the health department investigation should be shared with participating physicians, hospitals, and health departments.

Environmental Testing

Environmental testing, in the context of legionellosis, is the sampling of water and plumbing structures of a facility's water distribution system.

I. Single Cases:

The findings of the local health department investigation should determine whether or not any environmental testing is indicated. Most individuals have too many potential exposures during a typical incubation period to make such testing meaningful. (If the patient was diagnosed using the urine antigen test and no culture is available to speciate and serotype, environmental assessments have extremely limited value.) However, in some instances the investigation may uncover residential or occupational exposures known to be associated with Legionellosis cases. Environmental testing may be indicated in such cases.

II. Outbreaks

A. Any environmental exposures identified in the epidemiologic investigation that are significantly associated with disease transmission should be evaluated with environmental testing.

B. If patient culture isolates exist, these should be compared with environmental culture isolates by a reputable public health laboratory.

 

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50. Mietzner S, Schwille RC, Farley A, et al. Efficacy of thermal treatment and copper-silver ionization for controlling Legionella pneumophila in high-volume hot water plumbing systems in hospitals. Am. J. Infect. Control 1997;25:452-457.

51. Biurrun A, Caballero L, Pelaz C, et al. Treatment of a Legionella pneumophila-colonized water distribution system using copper-silver ionization and continuous chlorination. Infect. Control Hosp. Epidemiol. 1999;20:426-428.

52. Rohr U, Senger M, Selenda F, Turley R, Wilhelm M. Four years of experience with silver-copper ionization for control of Legionella in a German university hospital hot water plumbing system. Clin. Infect. Dis. 1999;29:1507-11.

53. Muraca P, Stout JE, Yu VL. Comparative assessment of chlorine, heat, ozone, and UV light for killing Legionella pneumophila within a model plumbing system. Appl. Environ. Microbiol. 1987;53:447-453.

54. Farr, B.M., et al. Evaluation of UV light for disinfection of hospital works contaminated with Legionella. Lancet 1988;2:669.

55. Personal communication, Barry Farr, MD

56. Cunliffe DA. Inactivation of Legionella pneumophila by monochloramine. J. Appl. Bacteriol. 1990;68:453-459.

57. Kool JL, Carpenter JC, Fields BS. Effect of monochloramine disinfection of municipal drinking water on risk of nosocomial Legionnaires' disease. Lancet 1999;353:272-277.

58. Pic-Albas L, Donegan NE, Witherell LE, et al. Short trial of monochloramine for Legionella disinfection in a hospital setting. Abstract, 4th Decennial International Conference on Nosocomial and Healthcare-Associated Infections. Atlanta, GA, March 5-9, 2000.

59. ASHRAE Guideline 12-2000. Minimizing the risk of legionellosis associated with building water systems. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Atlanta, GA., 1999. (available through the ASHRAE web site: www.ASHRAE.org)

60. Best M, Yu VL, Stout JE, et al. Legionellaceae in the hospital water supply- epidemiological link with disease and evaluation of a method of control of nosocomial Legionnaires’ disease and Pittsburgh pneumonia. Lancet 1983;2:307-310.

61. Allegheny County Health Department. Approaches to prevention and control of Legionella infection in Allegheny county health care facilities. 2nd ed. Pittsburgh, PA: Allegheny County Health Department. 1997:1-15.

62. Dixon Bruce. Statement to Time/CNN, broadcast Nov. 21, 1999

63. Stout JE, Yu VL. Nosocomial Legionella infection. In: Mayhall CG, ed. Hospital epidemiology and infection control, 2nd Ed. Philadelphia: Lippincott Williams and Wilkins, 1999:453-465.

64. Hart CA, Makin T. Legionella in hospitals: a review. J Hosp Infect 1991;18(Suppl A):481-489.

65. Benin AL, Benson RF, Arnold KE, Fiore AE, Cook PG, Williams LK, et al. An outbreak of travel-associated Legionnaires disease and Pontiac fever: The need for enhanced surveillance of travel-associated legionellosis in the United States. J Infect. Dis. 2002;185:237-243.

66. Bergmire-Sweat D. Legionellosis in Texas. Dis Prev News. 1995;55:1-2.

67. Ta AC, Stout JE, Yu VL, Wagener ML. Comparison of culture methods for monitoring Legionella species in hospital potable water systems and recommendations for standardization of such methods. J. Clin. Microbiol. 1995;33:118-212.

APPENDIX A

Membership of the Texas Legionnaires’ Disease Task Force

(listed in alphabetical order)

Anthony E. Bennett, RS
Public Drinking Water Program
Texas Natural Resources Conservation Commission
Austin, Texas

David Bergmire-Sweat, MPH
Infectious Disease Epidemiology and Surveillance Division
Texas Department of State Health Services
Austin, Texas

Nancy B. Bjerke, RN, MPH, CIC
Texas Hospital Association
Austin, Texas

Jim Clark
San Antonio Metropolitan Health District
San Antonio, Texas

Homer C. Emery, PhD
San Antonio Water System
San Antonio, Texas

Linda K. Gaul, PhD, MPH
Infectious Disease Epidemiology and Surveillance Division
Texas Department of State Health Services
Austin, Texas

Kate Hendricks, MD, MPH&TM
Director, Infectious Disease Epidemiology and Surveillance Division
Texas Department of State Health Services

Jessica Hilburn, BSMT (ASCP), CIC
Texas Society of Infection Control Practitioners
Austin, Texas

Gary Holmes, MD
Division of Infectious Disease
Scott & White Hospital
Temple, Texas

Bobby Jones, DVM
Tarrant County Health Department
Fort Worth, Texas

Robert Kimbrough, MD
Texas Tech University Health Sciences Center
Lubbock, Texas

C. Glen Mayhall, MD
University of Texas Medical Branch
Galveston, Texas

Ellen Musgrave, RN, CIC
Infection Control Practitioner
Southwest Texas Methodist Hospital
San Antonio, Texas

Neil Pascoe, BSN, RN, CIC
Infectious Disease Epidemiology and Surveillance Division
Texas Department of State Health Services
Austin, Texas

Dennis Perrotta, PhD, CIC
State Epidemiologist
Texas Department of State Health Services
Austin, Texas

Chip Riggins, MD, MPH
Director, Public Health Region 8
Texas Department of State Health Services
San Antonio, Texas

Maria C. Rodriguez, MD
Houston VA Hospital
Houston, Texas

Roger Sanchez
San Antonio Metropolitan Health District
San Antonio, Texas

Ian Shawcross
Facility Engineer
Southwest Texas Methodist Hospital
San Antonio, Texas

Paul Southern, MD
Southwestern Medical School
Dallas, Texas

APPENDIX B: DSHS Legionellosis reporting Form 5, 02/02; [Form (PDF PDF File: 31.9KB)]

APPENDIX C: Procedures for environmental testing for Legionella species

Specimen site selection protocol

1. Sample from all hot water tanks.

2. Sample from distal sites as follows:

a. If there are fewer than 500 hospital beds, sample from a minimum of 10 distal sites.

b. If there are more than 500 hospital beds, sample from 2 distal sites for every 100 beds.

Distal sites should be chosen from areas of the water system most likely to harbor Legionella (eg, areas where the bacteria have previously been found, dead ends), or other areas considered appropriate for the particular facility (eg, engineering factors associated with the growth of Legionella).

3. Sample first from faucets. If the faucets are culture-negative, sample again from showerheads.

Specimen collection protocol

1. Faucets

a. Moisten the outlet by allowing 4-5 droplets of water to trickle through the opening.

b. Insert a sterile cotton or Dacron swab into the faucet and rotate it 4 times around the inner circumference, beginning at the opening and moving up the faucet as far as the swab will reach.

c. Place the swab into the designated container.

d. If the swab system does not contain a transport medium, then allow 0.5 mL of water to flow from the faucet into the container to keep the swab moist.

2. Showerheads

a. Moisten the showerhead by allowing 4-5 droplets of water to trickle through the opening.

b. Rotate a sterile cotton or Dacron swab over the entire surface of the showerhead 4 times.

c. Place the swab into the designated container.

d. If the swab system does not contain a transport medium, then allow 0.5 mL of water to flow from the showerhead into the container to keep the swab moist.

3. Hot water tanks

a. Open the drain valve at the base of the tank.

b. Immediately collect 10-50 mL into a sterile specimen container.

c. Let water drain out of the pipe for 15-30 seconds to flush out residual water within the drainpipe.

d. Collect another 10-50 mL into a second specimen container.

This procedure ensures that both residual water in the drainpipe and water from the tank are sampled.

4. Refrigerate samples at 2-8oC.

Culturing protocol

1. Treat each swab or water sample with acid buffer (0.2 M HCl-KCl, pH 2.2) for 3 minutes. This maximizes the recovery of Legionella species and minimizes the growth of competing microorganisms.

2. Treat specimens.

a. Swabs: Immerse swab in 2.5 mL of acid buffer and shake vigorously.

b. Water samples:

i. Concentrate specimens by centrifugation at 1,000 X g for 10 minutes.

ii. Remove all but 1 mL of the supernatant and vortex the remaining specimen.

3. Inoculate samples.

a. Inoculate all samples onto both BCYE (nonselective medium) and DGVP (selective medium).

i. BCYE: buffered charcoal yeast extract

ii. DGVP: BCYE with glycine, vancomycin, polymyxin B, alpha-ketoglutarate, bromothymol blue and bromocresol purple dyes

a. Swabs:

i. Inoculate down the center of a plate by turning the swab to expose the entire surface.

7 ii. Use a sterile inoculating loop to streak the plate perpendicularly.

b. Water samples:

i. Plate 0.1 mL onto the media.

ii. Distribute the samples by using the spread plate technique.

4. Incubate plates at 35-37oC for 5-7 days.

5. Identification of isolates is based on colonial morphology, color, and inability to grow on blood agar. Serogrouping of Legionellaceae is done by slide agglutination and/or direct fluorescent antibody testing.

References: 42, 61, 67

 

APPENDIX D - Comparison table of Legionnaires' disease prevention and control guidelines

       

Centers for Disease Control and Prevention (2000)

 

State of Texas (2002)

State of Maryland (2000)

Allegheny County, PA (1997)

Diagnostic Capacity

Legionella spp. should be considered in the differential diagnosis of nosocomial and community-acquired pneumonia

All acute care and long-term care hospitals should provide urine antigen testing in-house or contract with a laboratory that can provide 48-hr turn-around.

All acute care hospitals should provide Legionella culturing on-site (if transplant patients present) or at another facility (if no transplant patients present) with 24-hr turn-around; long-term care facilities should have a mechanism in place to submit specimens for culturing to a laboratory

The state serves as reference laboratory; suspected nosocomial case specimens should be sent to the state lab

Legionella spp. should be considered in the differential diagnosis of nosocomial and community-acquired pneumonia

All acute care hospitals should provide urine antigen testing in-house

Legionella culturing should be performed on site (if transplant patients present) or at other facility (if no transplant patients present) with 24-hr turn-around

The state serves as reference laboratory; suspected nosocomial case specimens should be sent to the state lab

Laboratories should make available rapid testing for Legionella pneumophila serogroup 1 (e.g. urine antigen testing) and culturing for isolation of all Legionella species

Physicians should be educated on appropriate methods for diagnosis

Physicians should be provided with appropriate laboratory tests for diagnosis of Legionnaires' Disease

For hospitals with >400 beds:

  • Urine antigen testing and culturing should be available in the hospital

For hospitals with <400 beds and no transplant patients:

  • Urine antigen testing should be available on-site and there should be ready access to a laboratory for culturing

For all long-term care facilities:

  • Identify a laboratory that can perform urine antigen testing and Legionella culturing
         
         

 

       

Centers for Disease Control and Prevention (2000)

 

State of Texas (2002)

State of Maryland (2000)

Allegheny County, PA (1997)

Surveillance

Acute care hospitals:

Passive case detection (for a first case in a facility):

The hospital ICP should be notified within 1 day of positive diagnosis

If patient has symptoms consistent with Legionnaires’ disease, then patient should be considered a case

The case should be investigated to determine if it is nosocomial

Cases should be reported as either "definite" or “possible nosocomial" or “not nosocomial" within 1week of diagnosis

DSHS and CDC case report forms should be submitted

Outbreaks (>2 cases) should be reported immediately

Active case detection (after 1 nosocomial case)

Other pneumonia cases should be tested for possible Legionnaires' disease

All sputa and x-rays should be tested for possible Legionnaires' disease

Long-term care facilities:

Passive case detection:

As above for acute care facilities

Active case detection:

Increase surveillance for pneumonia cases and collect specimens from pneumonia patients

Community-acquired cases:

Passive case detection (with a single case):

The case should be reported to the health department

The case should be investigated to determine possible exposures

Case contacts should be educated

Active case detection (with >2 cases in 6 months):

Case finding should be conducted

Health care providers should be notified of a possible outbreak

Cases should be investigated to determine possible exposures

Results of the investigation should be shared with health care providers and the health department

Acute care hospitals:

Surveillance for primary prevention (when there are no diagnosed cases):

The hospital ICP should be notified within 1 day of positive assays

The case should be investigated to determine if it is nosocomial

Surveillance strategies should be developed to identify Legionnaires’ disease cases, including testing of other pneumonia cases for possible Legionnaires' disease and testing of broncoscopy specimens from patients with pneumonia

Hospitals should report cases to local health departments and complete the CDC case report form

Legionella infection should be made a reportable condition by the state legislature

Discussed under "Prevention," below

For all hospitals:

Educate healthcare workers and maintain a heightened suspicion for Legionella as a cause of nosocomial pneumonia

Culture or test all high risk patients with community and hospital-acquired pneumonia for Legionella

For all long-term care facilities:

Educate healthcare workers and maintain a heightened suspicion for Legionella as a cause of nosocomial pneumonia

Encourage physicians to culture or test high risk patients with community-and hospital-acquired pneumonia for Legionella

Notify the institution's ICP of a suspected case of nosocomial pneumonia among patients

         

 

       

Centers for Disease Control and Prevention (2000)

 

State of Texas (2002)

State of Maryland (2000)

Allegheny County, PA (1997)

Environmental (Water Distribution System) Testing

Acute care hospitals:

Assessment of Legionnaires' disease risk and criteria for environmental testing:

The risk of Legionnaires' disease transmission should be assessed

Environmental cultures should be taken only if it is determined that there is a significant risk of nosocomial transmission

Factors that affect the risk of nosocomial transmission in a facility include:

Environmental factors

Water chlorination type

Water temperature

Engineering factors

Design and materials used in the water system

Patient mix

Transplant patients, chemotherapy patients,

patients with chronic obstructive pulmonary

disease are at increased risk

Prior history

Prior Legionnaires' disease and/or Legionella positive water cultures

Procedures for environmental testing:

Culturing should be done only after assessment indicates risk of nosocomial transmission, when there are nosocomial cases, or when remediation has been completed

At risk facilities should:

Follow a standard protocol

Design their own protocol

Contract with experienced firms

Samples should be taken

Acute care hospitals:

Water distribution systems should be routinely cultured, with the time table determined by risk assessment

Periodicity and interpretation of environmental testing should be determined as part of an overall risk assessment process that considers both institutional risk factors and remediation efforts

Risk factors:

Engineering

Age, complexity, sedimentation, number of hot water systems

Patient mix

Transplant patients, chemotherapy patients, patients with chronic obstructive pulmonary disease

Prior history

Prior Legionnaires' disease and/or Legionella positive water cultures

Procedures for environmental testing:

Standardized procedures should be developed and followed

Results of testing should be qualitative for Legionella; serotyping and speciation, where necessary, should be included

Remediation: See under "Secondary Prevention," Below

Acute care hospitals:

All facilities should perform yearly environmental testing and test more often if transplants are performed

Environmental testing should include:

All hot water tanks

Faucets and showerheads at distal sites

 

 

 

 

 

 

 

 

 

 

Acute care hospitals:

No recommendation for routine culturing of water systems for Legionella

Culturing of the water system should be conducted if:

There is a case of Legionnaires' disease in an immunocompromised patient

The hospital houses immunocompromised patients

For hospitals with >400 beds:

Environmental testing would be appropriate:

Quarterly from faucets and showerheads at distal sites

Quarterly from all hot water tanks and sources

For hospitals with <400 beds and no transplant patients:

Environmental testing would be appropriate:

Semiannually from faucets and showerheads at distal sites

Annually from all hot water tanks and sources

For all long-term care facilities:

Environmental testing would be appropriate:

When there is a case of Legionella pneumonia

When there has been a cluster of nosocomial Legionella cases in the past 2 years

When there is an ongoing endemic problem of Legionella disease

         

 

     

Allegheny County, PA (1997)

Centers for Disease Control and Prevention (2000)

 

State of Texas (2002)

State of Maryland (2000)

Prevention

For all acute care hospitals and long-term care facilities:

Primary prevention (for facilities with no cases):

Education

Physicians - to heighten suspicion of nosocomial Legionnaires' disease

Other hospital personnel - about measures to control nosocomial legionellosis

Equipment cleanliness

Nebulizers, enteral tubes

Facility and physical plant control measures

High-risk patient facilities should not use large volume humidifiers

Cooling tower drift should be away from hospital's air intake system

Secondary prevention (for facilities with one definite or 2 possible nosocomial cases or with >30% of distal sites culture positive for Legionella):

Enhanced surveillance

Legionella testing for all new pneumonia cases for 6 months

Assessment of availability of laboratory testing and culturing of new suspect cases

Review of recent pneumonia cases for possibility of legionellosis

Consider the possibility of hospital-acquired cases among employees

Conduct environmental testing

Initiate case-control studies, as appropriate

Remediation

Methods include a variety of water treatment methods Engineering measures may also be incorporated

Protection of high risk patients - restricting their exposure to possibly Legionella contaminated water

For all acute care hospitals:

Primary prevention (for facilities with no cases):

Equipment cleanliness

Nebulizers, enteral tubes

Facility and physical plant control measures

High-risk patient facilities should not use large volume humidifiers

Cooling tower drift should be away from hospital's air intake system

Secondary prevention (when there is a nosocomial case or when Legionella is found above acceptable levels):

Enhanced surveillance

Review recent nosocomial pneumonia cases

Consider possibility of Hospital-acquired casesamong employees

Initiate case-control studies, as appropriate

Consider mandating Legionella testing for all

nosocomial pneumonia cases

Reassess availability of laboratory tests for Legionella

Enhance environmental surveillance, including additional cultures

Remediation Code of Maryland

Recommendations should be amended to set hot water temperatures in hospitals to <122oF

Installation of a new hot water system should include measures to reduce Legionella growth

An appropriate water treatment method should be selected

Engineering measures should be incorporated whenever possible

Protection of high risk patients - restricting their exposure to possibly Legionella contaminated water

For all hospitals, when >1 sites tests positive for Legionella:

Make available Legionella testing for patients with nosocomial pneumonia

Consider empiric anti- Legionella therapy for nosocomial pneumonia patients

Alert medical staff

If >30% of distal sites test positive for Legionella, initiate disinfection of water distribution system and follow with environmental testing

If <30% of distal sites test positive for Legionella, disinfection should proceed if determined necessary by hospital staff

Conduct surveillance for Legionella in patients with nosocomial pneumonia

If nosocomial Legionella pneumonia cases are found, implement in-house culturing capability

Disinfection measures:

Copper-silver ionization

Heating and flushing

Chlorination

Flash heating

Ultraviolet irradiation

Evaluate and possibly implement design, operation, and maintenance measures (engineering measures)

For all hospitals and long-term care facilities:

Primary prevention (when no cases are documented):

Equipment cleanliness

Nebulizers, enteral tubes

Limit or eliminate humidifiers

Cooling tower drift should be away from hospital's air intake system

No recommendation for continuous maintenance of water temperature at >50oC or <20oC, hyperchlorinating water, or treating water with ozone, UV, or metal ions

Secondary prevention (when there is one definite or 2 possible nosocomial cases, or if >30% of distal sites are positive for Legionella):

Contract local health department or CDC if disease is reportable or if assistance is needed

Conduct an investigation to determine the source of the Legionella if the facility has immunocompromised patients or a case in such a patient

If there are no immunocompromised patients, investigate to identify previous nosocomial cases

If there is continued nosocomial transmission:

Conduct environmental testing and save and subtype Legionella isolates from patients and facility to determine source

(Remediation:)

Decontaminate water system if source identified or if not but considered necessary

If water system implicated: Superheat or hyperchlorinate

Maintain water at > 50oC or or <20oC, or hyperchlorinate

Clean tanks and heaters

Limit water use of immunocompromised patients

If cooling towers implicated:

Decontaminate towers

Collect environmental samples for 3 months to assess efficacy of decontamination measures

         
       

Centers for Disease Control and Prevention (2000)

 

State of Texas (2002)

State of Maryland (2000)

Allegheny County, PA (1997)

         

Legionella
Control Plan

Each acute care hospital and long-term care facility should form a team of personnel from infection control, engineering and maintenance, risk management , employee health, and administration to develop a Legionella control plan. The plan should address issue of surveillance , environmental testing, remediation, and reporting.

Each hospital should formulate a group of representatives from various departments, such as infection control, engineering and maintenance, risk management, employee health, and administration to prevent and control Legionnaires' disease. The team should develop a written control plan that addresses surveillance, environmental culturing, remediation, and reporting.

(Not discussed)

Each hospital should create a Legionella team that answers to the hospital infection control committee. Each long-term care facility should place responsibility for Legionella control with its ICP, who works with a representative from facilities management.


Texas Department of State Health Services - Infectious Disease Control Unit
1100 West 49th Street, Suite T801, Mail Code: 1960 PO BOX 149347 - Austin, TX 78714-9347
(512) 458-7676 - Fax: (512) 458-7616 - E-Mail

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