Hospital Water Systems Research Articles

Control ofLegionella pneumophila in a hospital water system by chlorine dioxide

Immuno-compromised patients are particularly susceptible to Legionnaires' Disease. After three cases of the disease occurred in a hospital, a continuous dosing regime using chlorine dioxide was initiated to replace chlorination of the water system. This study identified a number of factors which may have resulted in conditions that would encourage the growth of the water-borne pathogen Legionella pneumophila. The residual chlorination was inadequate for microbial control at the taps furthest from the four storage tanks, of which two were found to be in excess for demand. The temperature of the water in the storage tanks was also found to be above 20 degrees C; a temperature that would encourage microbial growth. A back-up calorifier was present and was found to contain L. pneumophila, and linseed oil-based sealants that provide nutrients for microbial growth were also prevalent as jointing compounds in the water circuit. Although the shower heads were routinely disinfected, a requirement was identified to also disinfect the shower hoses. No L. pneumophila were recovered from the water system after the chlorine reduced dioxide disinfection trial. Biofilm was also dramatically reduced after disinfection; however, small microcolonies were identified and proved to be metabolically active when tested with a metabolic indicator. Using light and fluorescence microscopy, the pipe samples removed from the water system were rapidly analysed for biofouling, complementing existing microbiological methods.

Bronchoscopy-associated Mycobacterium xenopi pseudoinfections.

Mycobacterium xenopi typically accounts for less than 0.3% of all clinical mycobacterial isolates. Over a 37-mo period, 21 (35%) of 60 mycobacterial isolates from a Michigan hospital were identified as M. xenopi. Hospital, laboratory, and bronchoscopy records were reviewed to determine case characteristics, develop a case series, and calculate procedure-specific M. xenopi isolation rates. A case-control study was conducted to elucidate aspects of the bronchoscopy procedure associated with M. xenopi isolation. Bronchoscope cleaning procedures were reviewed, and hospital water systems were cultured. Four isolates were from three patients with disease attributable to M. xenopi. Of the other isolates, specimens obtained by bronchoscopy were more likely to yield M. xenopi than were specimens obtained by other routes (relative risk, 9.7; 95% confidence intervals, 3.2, 29.6). Bronchoscopes were disinfected in a 0.13% glutaraldehyde-phenate and tap-water bath and then were rinsed in tap water. Water from the hot water tank supplying this area yielded M. xenopi. Mycobacteria were cultured from bronchoscopes after disinfection. M. xenopi in the tap water appears to have contaminated the bronchoscopes during cleaning. Adequate disinfection of contaminated bronchoscopes and careful collection of specimens to avoid contamination with contaminated water are essential, both for limiting diagnostic confusion caused by mycobacterial pseudoinfections and for reducing risks of disease transmission.

Eradication of legionella from a hospital water system with tarn-pure copper/silver ionization

Eradication of legionella from a hospital water system with tarn-pure copper/silver ionization

Legionella Disinfection of Water Distribution Systems: Principles, Problems, and Practice

As laboratory diagnostic techniques for Legionella become more widespread (especially culture on selective dye-containing media and urinary antigen), more and more hospitals are discovering nosocomial legionellosis. As a result, disinfection directed at hospital water systems has assumed major priority. Many techniques are being applied, but an adequate assessment requires a minimum of three to five years so as to evaluate the long-term success or failure of any disinfection measure in an actual hospital water distribution system; hence, progress in this field has been necessarily slow. Nevertheless, cases of nosocomial legionellosis continue to appear, increasing pressures for hospitals to find solutions.

Prevention of Legionella Infections in a Bone Marrow Transplant Unit: Multifaceted Approach to Decontamination of a Water System

To evaluate measures intended to reduce Legionella infections in patients undergoing bone marrow transplantation (BMT). Ongoing clinical and microbiological surveillance for Legionella colonization or infection was undertaken. All neutropenic patients with pulmonary infiltrates and fever unresponsive to broad-spectrum antibiotics were tested for Legionella organisms. A 505-bed medical-surgical hospital with a designated BMT unit. Two hundred twenty-five patients underwent BMT; 201 were treated on a new BMT unit. The incidence of Legionella infections was compared to that seen in an estimated 150 neutropenic patients treated on other units. A combined approach to decontamination of a hospital water supply was assessed. This included heating, particulate filtration, ultraviolet sterilization, and monthly pulse hyperchlorination of water supplied to the BMT unit. The incidence of Legionella infections was assessed on the BMT unit and compared with the frequency elsewhere in the hospital. There were only three cases of Legionella pneumonia among 201 patients undergoing transplantation on a new BMT unit. In contrast, 33 cases of Legionella infections were detected from approximately 150 patients treated on general medical floors. A multifaceted approach to decontamination of a hospital water system led to a marked reduction in Legionella infections.

Monitoring of hospital water supplies for Legionella

In order to determine the value of regular surveillance for Legionella in the prevention of hospital-acquired (nosocomial) legionellosis, water samples were obtained over a three-year period from 17 hospitals located in England and Scotland. Prior to the study, all of the hospitals had in operation defined protocols and maintenance schedules which followed national guidelines for the prevention of legionellosis in health care premises. Six samples, from key locations in the water system of each hospital, were taken at six-monthly intervals. Total viable bacterial count (TVC), coliform count and Tegionella cultures were performed on all the samples. No coliforms were detected in any of the samples, whereas the TVC was variable. Legionella pneumophila was isolated from both the hot and cold water supplies of two hospitals. The TVC was not related to the isolation of Legionella. Confirmation of the presence of Legionella was subsequently attributed to defects in the equipment and water maintenance programmes. It was concluded that the microbiological examination of water is an effective approach to the audit of the maintenance of hospital water systems in order to prevent legionellosis.

Distribution of legionellae in a hospital water system: prevalence of immunologically and genetically related Legionella pneumophila serogroup 6 isolates

A hospital warm water system was monitored for the presence and distribution of legionellae. Subtyping of ten selected Legionella pneumophila isolates, originating from four different sites in the system by using serogroup specific antisera in an indirect immunofluorescence test, revealed that nine of the ten isolates belonged to serogroup 6, while the remaining one was serogroup 10. Two monoclonal antibodies (mAbs) specific for a subgroup of serogroup 6 strains were further used for characterization. None of the strains reacted with these mAbs. Genome analysis by elaborating NotI profiles using the pulsed field gel electrophoresis (PFGE) technique revealed that nearly all serogroup 6 isolates derived from different sites, including a new building connected by a ring pipe, were identical according to restriction fragment patterns. The patterns were distinguishable from those of the two L. pneumophila serogroup 6 reference strains, and from that of the L. pneumophila serogroup 10 isolate. These data argue for a relatively homogeneous L. pneumophila serogroup 6 population in the entire water system.

Distribution of legionellae in a hospital water system: prevalence of immunologically and genetically relatedLegionella pneumophilaserogroup 6 isolates

Distribution of legionellae in a hospital water system: prevalence of immunologically and genetically related<i>Legionella pneumophila</i>serogroup 6 isolates

Chlorination of Water Supplies to Control Legionella May Corrode the Pipes

To the Editor.— We read with interest the article by Helms et al 1 that describes continuous hyperchlorination of a hospital water system and wish to comment on their observations in view of our own experience with this technique. Following two major outbreaks of legionnaires' disease at this institution in 1980, continuous hyperchlorination of the hospital's hot water system was begun in 1981, with attempts made to maintain chlorine levels of 1.5 mg/L of free chlorine. Although Legionella could no longer be cultured from hot water samples, by 1984 major corrosion damage to the copper plumbing system had occurred, resulting in unacceptable maintenance costs, disruption of patient care activities, and concern about disintegration of the entire water distribution system. An environmental engineer (J.W.P.) was consulted and documented two different types of copper corrosion: (1) a slow, uniform corrosion that occurred when chlorine levels were low and the water pH somewhat acidic

Legionnaires' disease associated with a hospital water system. A five-year progress report on continuous hyperchlorination

In 1981, sixteen cases of nosocomial legionellosis occurred among 456 patients admitted to a new hematology-oncology unit (35 per 1000 admissions). Monoclonal antibody typing and restriction endonuclease plasmid analysis identified a unique strain (09,04) of<i>Legionella pneumophila</i>serogroup 1 isolated from both patients and water outlets. Continuous hyperchlorination of the hot and cold water began in January 1982, and chlorine levels of 3 to 5 mg/L have been maintained most recently. Water samples have been consistently negative for<i>Legionella</i>for more than five years. Four sporadic cases of nosocomial legionellosis have occurred in the hematology-oncology unit during the same period (one per 1000 admissions) associated with a different strain of<i>L pneumophila</i>serogroup 1 (09,00). The environmental reservoir(s) of<i>L pneumophila</i>serogroup 1 in these cases has not been identified. Levels of trihalomethanes (potential carcinogens) were high (&gt;100 μg/L) when chlorine levels of hot water exceeded 4 mg/L. Some corrosion damage to the water distribution system has occurred: the average number of leaks per month increased steadily from zero in 1982 to 5.2 in 1986. The chlorinator installation costs were $75 800, and annual operation expenses were $12 500. Continuous hyperchlorination is a promising but still experimental technique for control of nosocomial legionellosis. In our experience, epidemic disease has been controlled, but sporadic cases have continued to occur. (<i>JAMA</i>1988;259:2423-2427)

Legionnaires' disease outbreaks—the engineering implications

It has long been known that hepatitis A, salmonellosis, dysentery and other gastrointestinal infections may result from drinking water from contaminated potable supplies. Fortunately it is a rare event for potable supplies to be contaminated in this country but it is a potential hazard, particularly in all those hospitals still supplying drinking water from their own reservoirs or holding tanks. In recent years it has been recognized that cooling waters and domestic water systems in hospitals may also serve as sources of certain infections (B roome, 1984; Bartlett, 1984). Legionnaires’ disease, caused by the bacterium Legionella pneumophila, is one such infection which occurs both in outbreaks and endemically in hospitals Hot water systems have been shown to be the most important source, with the infection being acquired not by ingestion but through the inhalation of water droplets. Other organisms such as Acinetobacter lwofii, Micrococcus varians and Pseudomonas stutzeri, may also colonize hospital domestic hot water systems and produce disease in patients whose normal defences are weakened by illness or treatment (Meers, 1981). In general the prevention of such infections from hospital water systems depends on the maintenance of good engineering housekeeping practices. The aim of this paper is to set out in some detail those steps which might be taken when a hospital outbreak occurs and a water system identified as the source by epidemiological and microbiological studies. These proposed control measures were drawn up in consultation with microbiologists and epidemiologists and are based largely on personal experience gathered in the control of the outbreak of Legionnaires’ disease in Kingston District General Hospital in 1980 (Fischer-Hoch et aE., 1981; Fischer-Hoch, Smith & Colbourne, 1982) and several outbreaks in hotels both in the UK and overseas.

Legionella pneumophila in a hospital water system following a nosocomial outbreak: prevalence, monoclonal antibody subgrouping and effect of control measures

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Routine Culturing for Legionella in the Hospital Environment May Be a Good Idea: A Three-Hospital Prospective Study

The source for nosocomial Legionnaires’ disease is the water distribution system. However, the implications for legionella contamination in a hospital without known Legionnaires’ disease is unclear. Therefore, culturing for Legionella pneumophila in the environment has not been routinely recommended. The authors conducted a prospective pneumonia study in three hospitals, none of which was known to have a major problem with endemic legionellosis. The water system of Hospital 1 was colonized with L. pneumophila, serogroup 1; Hospital 2 was colonized by L. pneumophila, serogroup 5 (which is rarely associated with disease); Hospital 3 was essentially free of L. pneumophila. Sputum culture on selective legionella media, direct fluorescent antibody testing, and serology were performed for all nosocomial pneumonias regardless of clinical impression. At the end of the study the incidence of nosocomial legionnaires’ disease was found to be 9%, 0%, and 0% in Hospitals 1,2, and 3, respectively. In Hospital 1, monoclonal antibody subtyping confirmed that the patient isolates were identical to the environmental isolates. The authors conclude that environmental culturing, despite the absence of known Legionnaires’ disease, is useful. Positive cultures from the hospital water supply would mandate the introduction of legionella testing into the laboratory and stimulate physicians to consider Legionnaires’ disease when encountering nosocomial pneumonias.

Legionella pneumophila in a hospital water system following a nosocomial outbreak: prevalence, monoclonal antibody subgrouping and effect of control measures.

Swabs and water samples from a hospital water system were cultured for legionellae over an extended period. Legionella pneumophila serogroup 1, including outbreak associated strains, were isolated in small numbers from approximately 5% of these samples despite implementation of the current DHSS/Welsh Office regulations. No cases of nosocomial legionnaires' disease were proven during the study. Physical cleaning and chemical sterilization of taps, and replacement of washers with 'approved' brands did not eradicate the organisms. Eradication of legionellae in hospital water supplies appears to be unnecessary in preventing nosocomial legionnaires' disease provided the current DHSS/Welsh Office recommendations are implemented.

Legionnaires' disease outbreaks--the engineering implications.

It has long been known that hepatitis A, salmonellosis, dysentery and other gastrointestinal infections may result from drinking water from contaminated potable supplies. Fortunately it is a rare event for potable supplies to be contaminated in this country but it is a potential hazard, particularly in all those hospitals still supplying drinking water from their own reservoirs or holding tanks. In recent years it has been recognized that cooling waters and domestic water systems in hospitals may also serve as sources of certain infections (B roome, 1984; Bartlett, 1984). Legionnaires’ disease, caused by the bacterium Legionella pneumophila, is one such infection which occurs both in outbreaks and endemically in hospitals Hot water systems have been shown to be the most important source, with the infection being acquired not by ingestion but through the inhalation of water droplets. Other organisms such as Acinetobacter lwofii, Micrococcus varians and Pseudomonas stutzeri, may also colonize hospital domestic hot water systems and produce disease in patients whose normal defences are weakened by illness or treatment (Meers, 1981). In general the prevention of such infections from hospital water systems depends on the maintenance of good engineering housekeeping practices. The aim of this paper is to set out in some detail those steps which might be taken when a hospital outbreak occurs and a water system identified as the source by epidemiological and microbiological studies. These proposed control measures were drawn up in consultation with microbiologists and epidemiologists and are based largely on personal experience gathered in the control of the outbreak of Legionnaires’ disease in Kingston District General Hospital in 1980 (Fischer-Hoch et aE., 1981; Fischer-Hoch, Smith & Colbourne, 1982) and several outbreaks in hotels both in the UK and overseas.

Epidemiological complexity of hospital aeromonas infections revealed by electrophoretic typing of esterases.

An epidemiology analysis of a series of 12 Aeromonas hydrophila infections, including six of septicaemia, which occurred on several wards of one hospital during the summer of 1982 is presented. The hypothesis that the hospital water could be the source of these infections was supported by the isolation of 1-10 motile aeromonads per ml in most of the water samples collected from various points on the hospital water system. Electrophoretic esterase typing was used as an epidemiological screening method to determine the relationship between bacterial strains isolated from the patients and those from water samples. The epidemiology of A. hydrophila infection in the hospital was found to be complex. Amongst the 15 strains of A. hydrophila isolated from patients were 8 zymotypes, while amongst the 126 strains from the water samples there were 37. In some cases, several zymotypes were isolated simultaneously from the same tap water. On one ward, the same zymotype was found in 2 patients and in 2 water samples. The prophylactic measures taken in 1982-5 to avoid oral contamination of immuno-compromised patients with infected hospital water have significantly reduced the number of cases of septicaemia. This success has constituted additional retrospective evidence for the water-borne origin of these infections.

Nosocomial outbreak of Legionnaires' disease: molecular epidemiology and disease control measures.

Molecular laboratory techniques were used to study the epidemiology of an outbreak of nosocomial Legionnaires' disease. All patient isolates were Legionella pneumophila serogroup 1 and showed identical plasmid profiles and reactions with serogroup-specific monoclonal antibodies. L pneumophila was also cultured from four of five cooling tower water samples; however, the isolate from only one tower was serogroup 1 of the same subtype as patient isolates. Since the cases were temporally clustered and epidemiologically associated with exposure to cooling tower aerosols, the single cooling tower implicated by molecular analysis was the most likely source of the outbreak. Chlorination of cooling tower ponds has eradicated the epidemic strain. Since potable water also harbored the infecting organism and was the probable source for cooling tower contamination, decontamination of the hospital water system was also undertaken. Superchlorination of hot water holding tanks to 17 ppm on a weekly basis has effectively eradicated L pneumophila from the potable water system and appears to be a reasonable, simple, and relatively inexpensive alternative to previously described methods of control.

Potable water as a source of Legionnaires' disease

A three-year epidemic of legionnaires' disease in a hospital was dramatically curtailed following hyperchlorination of the potable water supply. The hypothesis that potable water was the source for the outbreak was further supported by isolation of<i>Legionella pneumophila</i>(the agent of legionnaires' disease) from the hospital water supply, observation that a sudden upsurge had occurred in the number of cases following a peculiar manipulation of the hospital water system, and documentation of a 30-fold increase in concentration of organisms in the water when this manipulation was artificially recreated. Thus, potable water may be an important source of epidemic legionnaires' disease and continuous hyperchlorination a method of control. (<i>JAMA</i>1985;253:1412-1416)

Potable Water as a Source of Legionnaires' Disease

A three-year epidemic of legionnaires' disease in a hospital was dramatically curtailed following hyperchlorination of the potable water supply. The hypothesis that potable water was the source for the outbreak was further supported by isolation of Legionella pneumophila (the agent of legionnaires' disease) from the hospital water supply, observation that a sudden upsurge had occurred in the number of cases following a peculiar manipulation of the hospital water system, and documentation of a 30-fold increase in concentration of organisms in the water when this manipulation was artificially recreated. Thus, potable water may be an important source of epidemic legionnaires' disease and continuous hyperchlorination a method of control.

Legionnaires' disease associated with a hospital water system: a cluster of 24 nosocomial cases.

Over a 10-month period, 24 cases of Legionnaires' disease pneumonia occurred among patients admitted to an Iowa hospital, most of whom were immunosuppressed. Eleven patients died. Twenty-one patients were admitted to a recently completed hospital addition, 16 of these to a new hematology-oncology unit. Legionella pneumophila serogroup 1 was isolated from the patients, water outlets, and hot water in the new addition. Water quality variables in the hospital addition were adequate. Shock chlorination, temporary elevation of the hot water temperature, and continuous chlorination of hospital water decreased the frequency of isolation of Legionella. Water use by patients in the hematology-oncology unit was restricted until the water was free of Legionella. The incidence of Legionnaires' disease decreased. Indirect evidence supports an hypothesis of water-borne disease in this cluster of cases. Current variables of acceptable water potability may not guarantee water free of L. pneumophila.