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FAQ FOR INFECTION CONTROL

• Preventing Legionnaires’ disease in Long Term Care facilities

• Decorative fountains in hospitals ?

• Can Legionnaires' disease be contracted from decorative fountains?

• Legionella species other than L pneumophia in the hospital water supply. Should we disinfect?

• Rinsing transesophageal probes with hospital tap water?

• Legionella and refrigerated water fountains?

• CFUs/ml as a guide to remedial action

• Is routine environmental surveillance the standard of practice?

• Monochloramine in the municipal water supply and the need for hospital monitoring for legionella?

• First draw water sample for legionella culturing of distal water sites?

• Legionella gormanii and L pneumophila, serogroup 3 in the hospital water.

• Regulations for maintenance of hospital water supplies?

• Frequency of Legionella monitoring of hospital water?

• Is Legionella anisa in the hospital water a concern?
   

Do you believe there is a benefit to residents in LTC facilities in identifying Legionella infections?  What interventions can LTC facilities implement to prevent and manage these infections.

        Legionella infection, on the other hand, is acquired from the environment.  If there is no Legionella in the environment, then disease cannot occur.  Thus, unlike most types of pneumonia in the long-term care setting, Legionella is highly preventable.  In addition, most patients in long-term care facilities are treated for infection without benefit of specific microbiologic diagnosis.  In the case of pneumonia, this is particularly true, since sputum samples are notoriously hard to obtain in this population. A diagnosis of Legionnaires’ disease permits specific, pathogen directed therapy, and avoids overly broad empiric therapy (identified by many experts as a particular issue in nursing homes).

Our hospital installed the attached fountain in our new lobby, contrary to the department of infection control’s recommendation.  It recirculates the water from the pool to the top where it dribbles down the rock face.  Has legionellosis ever been shown to be caused by such a fountain?  What would your recommendation be regarding assessing the fountain directly for Legionella? 

The evidence that decorative fountains are a disseminator for Legionella is surprisingly weak. That said, we discourage installation of fountains in hospitals because of the anxiety that such fountains bring when Legionella outbreaks are attributed to such devices.  However, in this particular case, it appears that the design is not one of intense aerosolization with spraying water. So, the risk of contracting Legionella by aerosolization is exceedingly low.

We perform environmental testing for Legionella in our hospital water supply. If Legionella that fluoresces under UV light (bozemanii, gomanii, dumoffii, anisa, cherri, steigerwalti, gratiana, tucsonensis, parisiensis, rubrilucens and erythra) are found, should the water system be disinfected? Is there any relationship between these species and infection to humans?

In general, if no cases of Legionella have been discovered due to these non-pneumophila species, you do not need to disinfect. If cases due to these species are found, disinfection should be initiated if two (2) conditions are both fulfilled: 1) Immunosuppressed hosts especially transplant patients are being hospitalized at your facility, 2) Distal site positivity is >30% for that Legionella species.

Our facility (hospital) has Legionella in its water system and cases of hospital-acquired Legionnaires’ disease, and there currently is a prohibition against drinking the hospital water.  All patients are getting their water via bottled water.  Is the fact that TEE probes (transesphageal echo) are being rinsed with hospital tap water a problem for infectivity? 

        This is an important question that you have raised. You are correct. Sterile water should be used for rinsing TEE probes.  Please inform your Infection Control practitioner that sterile water must also be used for rinsing nasogastric tubes and respiratory tract equipment.  Interestingly, there is a report of 3 cases of hospital-acquired LD transmitted by TEE probes (Levy PY, Infect Control Hosp Epidemiol Aug 2003).

I am an Infection Control Nurse and want to get your get your opinion on some questions pertaining to a Legionella environmental surveillance.  This is a controversial topic as CDC has not officially provided any recommendation while you have been prominent advocates of routine surveillance.  I am working on policy development and problem solving and would like to get your input on the following questions?

1.  Have you heard of any linkage to Legionella associated with refrigerated portable water fountains or coolers?  Is there any information or guidance about flushing refrigerated water fountains on a routine basis to decrease risks?

Many years ago, there was a dramatic increase in the concentration of Legionella (and a shift in species) isolated from our chilled drinking water system. Our usual experience was to find low concentrations of L. bozemanii (blue-white fluorescing species rarely associated with infection).  Then one day our water fountain cultures were covered with (>3000 cfu) with Legionella pneumophila, serogroup 1. The compressor/chiller had malfunctioned a few weeks previously and that a new one was on order.  This system was a recirculating system with 2-3 fountains/floor on this system.  After the chiller failed, the water was no longer cold enough to inhibit Legionella pneumophila from growing in the system. We did try to hyperchlorinate the system, with the expected result -recolonization after a few weeks.  Ultimately, we replaced the old recirculating system with stand-alone units.  Now we rarely have a positive culture from these units and the water is very cold.

2.  A technical bulletin from PathoCon Laboratories has a table with suggested Legionella Remedial Action criteria. They list various detectible limits of CFUs/ml as a guide for remedial action.  For example, 10⁹ CFUs may require cleaning and/or biocide treatment of equipment if indicated in potable water. Do you have any current information or references with action level based on CFU’s/ml.

            It is logical that the overall burden of Legionella within the water distribution system should correlate roughly with the risk for contracting Legionnaires’ disease. While cfu/ml quantitation seems to be an intuitively plausible concept, in actuality, our studies showed that quantitation is highly variable.  One reason is that Legionella resides within a biofilm coating in each pipe or distal fixture.  When repeat samples are taken from the same site within a short period of time, the cfu/ml may vary widely.  Also, water usage at that site and frequency of sampling from that site can also affect cfu/ml. 

            In short, no evidence exists to show that quantitation is useful for predicting risk, but considerable data exists to show it is an inherently unstable method.  The recommendations from our website are evidence-based so we would not use this table as a guideline for remedial action.  In contrast, the percent distal site positivity does correlate with occurrence of disease. 

3.  Is environmental surveillance becoming a standard of practice in most hospital settings?

            The following countries now recommend routine environmental surveillance for Legionella in hospitals:  Denmark, France, Germany, Taiwan, and in addition, the cities of Barcelona, Spain; Pittsburgh, PA; and the State of Maryland.   U.S. CDC recommends routine surveillance if transplants are being performed at that hospital. 

What would you recommend as a monitoring program for our hospital given the fact that our municipality is using monochloramine.  We perform environmental cultures for Legionella on a regular basis.  Our distal water sites are consistently negative.  Our laboratory also has Legionella culture and the urinary antigen test to be used for both community-acquired and hospital-acquired pneumonia. 

            Regarding your Legionella monitoring program, we congratulate you on having diagnostic capability in-house.  Many hospitals still send these tests out to reference labs and as a consequence, the physicians do not use the tests, because it takes too long to get a result.  Given that your municipality is using monochloramine and that you have a history of negative culture results from your distal outlets, we would recommend that you revert to performing environmental monitoring once a year. 

Our approach to culturing environmental samples in our hospital is to collect 1 liter water samples from a tap after the water has been run until it gets "hot"--some sites may take several minutes before the sample is collected.  After looking at our numbers, and reading about different ways to collect the sample, I realize that we probably are NOT getting a good representation of the distal site, but more of what is present centrally.  We prefer to collect water rather than swab so we can get a quantitative number (I did read your paper recommending the swab as the more sensitive though!--I am concerned that there may be a great deal of variability in how a swab would be collected).  Would it be better for us to collect the sample immediately after turning on the tap, and collecting a smaller volume?  We really can't do an immediate and a post flush-- we have a difficult enough time having the state lab to handle one sample/site!

One liter samples are not necessary.  Our experience and studies have has shown that the first draw sample is a more sensitive sample than a "post-flush" sample.  In addition, we sampled approximately 100ml, and plated 0.1 mL directly and after concentration by filtration (100mL filtered and resuspended in 10mL).  We validated this method by performing a multi-center study and correlated site positivity with disease incidence using this method (article in press).  You are correct that variability in quantitative counts exist for swabs, but variability also exists for water.  So, quantitation is simply too variable to be useful.

Legionella gormanii and L. pneumophila, serogroup 3 are in our hospital water supply.  In a newly constructed hospital (280 beds) we have detected the presence of Legionella in the hot water system only after a few months. The results of the samples collected immediately after commissioning were negative.  After 5 months, the routine surveillance of the water quality revealed a weak contamination of the hot water distribution system with L. pneumophila serogroup 3 (< 1000 cfu/l). To our surprise we found Legionella gormanii (concentrations between 1500 and 12000 cfu/l) on several water outlets in patient rooms (like wallmount faucets and thermostatic shower valves). We have never heard of this species. By reviewing the literature, we found only 2 articles:  First isolation of Legionella gormanii from human disease - Griffith et al. - 02/1988.  Legionella gormanii sp. Nov. - Morris et al. - 11/1980.  Is the virulence of L. gormanii comparable to that of Legionella pneumophila?

        Legionella gormanii is one of the avirulent Legionella species, although cases of infection have been described. Isolation of this species from your water supply is not a major cause of concern. L. pneumophila serogroup 3 is also a species that has rarely been implicated in disease.  So, you probably need not disinfect your system if the only organisms are L. pneumophila serogroup 3 and L. gormanni.  Ideally, all patients with hospital-acquired pneumonia should be cultured for Legionella.  The urinary antigen will detect only L. pneumophila, serogroup 1, and cannot detect L. pneumophila, serogroup 3, or L. gormanii.  If Legionella cultures are unavailable, perhaps a quinolone should be added to cases of hospital-acquired pneumonia that do not have a clear-cut etiologic diagnosis. 

Two reviews of Legionella gormanii are in the Publication Sections of www.legionella.org  under “Other Legionella Species including Pittsburgh Pneumonia Agent.”

Fang GD. Disease due to the legionellaceae (other than L. pneumophila): historical, microbiological, clinical, and epidemiological review. Medicine 1989;68:116-132.

7 cases of L. gormanii are reviewed in this article. 

Muder RR. Infection due to Legionella species other than L. pneumophila. Clin Infect Dis 2002;35: 990-998.

Are the normal regulations and planning rules applied for system design (temperature > 55^oC, no dead legs or stagnation, circulation loops, maintenance, monitoring, etc.) sufficient to control the presence of Legionella in the hot water systems?

        Download Lin's articles on Disinfection in the Publications section. None of the measures mentioned including maintenance or removal of deadlegs affect legionella colonization!  Maintaining hot water temp at > 55^oC is effective for a period of time only if a superheat and flush was performed previously.

What frequency would you recommend for monitoring Legionella in hot water systems of hospitals?

        At least once a year if there are no cases.  See the algorithm in ACHD Guidelines on the Home Page of www.legionella.org . Use the results of the environmental cultures to assess the risk of Legionnaires’ disease at your facility. 

Is Legionella anisa in our hospital water a concern?

        Legionella anisa is a fairly common environmental species.  In a recent survey we have found that about 20% of hospitals in the US are colonized; the number of reported cases of infection is extremely low.  There is a reported outbreak of non-pneumonic legionellosis ("Pontiac Fever") due to L. anisa occurring in an automobile plant due to contaminated, aerosol generating equipment.  There is limited laboratory evidence to suggest that L. anisa may be somewhat less pathogenic that L. pneumophila, at least based on an ability to infect mammalian cells.

        The risk of disease after exposure to environmental L. anisa by healthy people, or the general hospital patient population is exceedingly low.  It might be advisable, however, to protect highly immunocompromised patients, such as transplant patients, patients on high dose corticosteroids, from exposure.

Key references:

1: La Scola B, Mezi L, Weiller PJ, Raoult D. Isolation of Legionella anisa using an amoebic coculture procedure. J Clin Microbiol. 2001 Jan;39(1):365-6. PMID: 11136802.

2: Fields BS, Barbaree JM, Sanden GN, Morrill WE. Virulence of a Legionella anisa strain associated with Pontiac fever: an evaluation using protozoan, cell culture, and guinea pig models. Infect Immun. 1990 Sep;58(9):3139-42. PMID: 2117580.

3: Fenstersheib MD, Miller M, Diggins C, Liska S, Detwiler L, Werner SB, Lindquist D, Thacker WL, Benson RF. Outbreak of Pontiac fever due to Legionella anisa. Lancet. 1990 Jul 7;336(8706):35-7. PMID: 1973219.

4: Fallon RJ, Stack BH. Legionnaires' disease due to Legionella anisa.J Infect. 1990 May;20(3):227-9 PMID:2341733.

5: Thacker WL, Benson RF, Hawes L, Mayberry WR, Brenner DJ. Characterization of a Legionella anisa strain isolated from a patient with pneumonia. J Clin Microbiol. 1990 Jan;28(1):122-3. PMID: 2405005.

6: Bornstein N, Mercatello A, Marmet D, Surgot M, Deveaux Y, Fleurette J. Pleural infection caused by Legionella anisa. J Clin Microbiol. 1989 Sep; 27(9):2100-1. PMID: 2778073.