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 Legionnaires' disease, 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 Legionnaires' disease or Pontiac fever 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] 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 Legionnaires' Disease 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.
(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.
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]).
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 60^oC (140^oF) and reduced to 50^oC (122^oF) 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.

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