Nosocomial Outbreak of Legionnaires' Disease: Molecular Epidemiology and Disease Control Measures

1987 ◽  
Vol 8 (2) ◽  
pp. 53-58 ◽  
Author(s):  
Jeffrey M. Johnston ◽  
Robert H. Latham ◽  
Frederick A. Meier ◽  
Jon A. Green ◽  
Rebecca Boshard ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Potable Water ◽  
Cooling Tower ◽  
Water System ◽  
Hot Water ◽  
Control Measures ◽  
Laboratory Techniques ◽  
Legionnaires Disease ◽  
Water Holding ◽  
Methods Of Control

AbstractMolecular 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 sub-type 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.

scholarly journals The Stafford outbreak of Legionnaires’ disease

1990 ◽  
Vol 104 (3) ◽  
pp. 361-380 ◽  
Author(s):  
M. C. O'Mahony ◽  
R. E. Stanwell-Smith ◽  
H. E. Tillett ◽  
D. Harper ◽  
J. G. P. Hutchison ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Air Conditioning ◽  
Cooling Tower ◽  
Ventilation System ◽  
Water System ◽  
Cooling Water ◽  
District General Hospital ◽  
Control Measures ◽  
Epidemic Strain ◽  
Legionnaires Disease

SUMMARYA large outbreak of Legionnaires’ disease was associated with Stafford District General Hospital. A total of 68 confirmed cases was treated in hospital and 22 of these patients died. A further 35 patients, 14 of whom were treated at home, were suspected cases of Legionnaires’ disease. All these patients had visited the hospital during April 1985. Epidemiological investigations demonstrated that there had been a high risk of acquiring the disease in the out patient department (OPD), but no risk in other parts of the hospital. The epidemic strain ofLegionella pneumophila, serogroup 1, subgroup Pontiac la was isolated from the cooling water system of one of the air conditioning plants. This plant served several departments of the hospital including the OPD. The water in the cooling tower and a chiller unit which cooled the air entering the OPD were contaminated with legionellae. Bacteriological and engineering investigations showed how the chiller unit could have been contaminated and how an aerosol containing legionellae could have been generated in the U–trap below the chiller unit. These results, together with the epidemiological evidence, suggest that the chiller unit was most likely to have been the major source of the outbreak.Nearly one third of hospital staff had legionella antibodies. These staff were likely to have worked in areas of the hospital ventilated by the contaminated air conditioning plant, but not necessarily the OPD. There was evidence that a small proportion of these staff had a mild legionellosis and that these ‘influenza–like’ illnesses had been spread over a 5–month period. A possible explanation of this finding is that small amounts of aerosol from cooling tower sources could have entered the air–intake and been distributed throughout the areas of the hospital served by this ventilation system. Legionellae, subsequently found to be of the epidemic strain, had been found in the cooling tower pond in November 1984 and thus it is possible that staff were exposed to low doses of contaminated aerosol over several months.Control measures are described, but it was later apparent that the outbreak had ended before these interventions were introduced. The investigations revealed faults in the design of the ventilation system.

scholarly journals Lessons From an Outbreak of Legionnaires’ Disease on a Hematology-Oncology Unit

2016 ◽  
Vol 38 (3) ◽  
pp. 306-313 ◽  
Author(s):  
Louise K. Francois Watkins ◽  
Karrie-Ann E. Toews ◽  
Aaron M. Harris ◽  
Sherri Davidson ◽  
Stephanie Ayers-Millsap ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Potable Water ◽  
Single Case ◽  
Healthcare Providers ◽  
Water System ◽  
Positive Sequence ◽  
Environmental Isolates ◽  
Legionnaires Disease ◽  
Oncology Unit ◽  
Healthcare Associated

OBJECTIVESTo define the scope of an outbreak of Legionnaires’ disease (LD), to identify the source, and to stop transmission.DESIGN AND SETTINGEpidemiologic investigation of an LD outbreak among patients and a visitor exposed to a newly constructed hematology-oncology unit.METHODSAn LD case was defined as radiographically confirmed pneumonia in a person with positive urinary antigen testing and/or respiratory culture forLegionellaand exposure to the hematology-oncology unit after February 20, 2014. Cases were classified as definitely or probably healthcare-associated based on whether they were exposed to the unit for all or part of the incubation period (2–10 days). We conducted an environmental assessment and collected water samples for culture. Clinical and environmental isolates were compared by monoclonal antibody (MAb) and sequence-based typing.RESULTSOver a 12-week period, 10 cases were identified, including 6 definite and 4 probable cases. Environmental sampling revealedLegionella pneumophilaserogroup 1 (Lp1) in the potable water at 9 of 10 unit sites (90%), including all patient rooms tested. The 3 clinical isolates were identical to environmental isolates from the unit (MAb2-positive, sequence type ST36). No cases occurred with exposure after the implementation of water restrictions followed by point-of-use filters.CONCLUSIONSContamination of the unit’s potable water system with Lp1 strain ST36 was the likely source of this outbreak. Healthcare providers should routinely test patients who develop pneumonia at least 2 days after hospital admission for LD. A single case of LD that is definitely healthcare associated should prompt a full investigation.Infect Control Hosp Epidemiol2017;38:306–313

scholarly journals Integrated Real-Time PCR for Detection and Monitoring of Legionella pneumophila in Water Systems

2006 ◽  
Vol 73 (5) ◽  
pp. 1452-1456 ◽  
Author(s):  
Diaraf Farba Yaradou ◽  
Sylvie Hallier-Soulier ◽  
Sophie Moreau ◽  
Florence Poty ◽  
Yves Hillion ◽  
...  
Keyword(s):  
Real Time ◽  
Legionella Pneumophila ◽  
Cooling Tower ◽  
Water System ◽  
Culture Method ◽  
Hot Water ◽  
Pcr Assay ◽  
Standard Culture ◽  
Serial Samples ◽  
Over Time

ABSTRACT We evaluated a ready-to-use real-time quantitative Legionella pneumophila PCR assay system by testing 136 hot-water-system samples collected from 55 sites as well as 49 cooling tower samples collected from 20 different sites, in parallel with the standard culture method. The PCR assay was reproducible and suitable for routine quantification of L. pneumophila. An acceptable correlation between PCR and culture results was obtained for sanitary hot-water samples but not for cooling tower samples. We also monitored the same L. pneumophila-contaminated cooling tower for 13 months by analyzing 104 serial samples. The culture and PCR results were extremely variable over time, but the curves were similar. The differences between the PCR and culture results did not change over time and were not affected by regular biocide treatment. This ready-to-use PCR assay for L. pneumophila quantification could permit more timely disinfection of cooling towers.

scholarly journals Quantitative Real-Time Legionella PCR for Environmental Water Samples: Data Interpretation

2006 ◽  
Vol 72 (4) ◽  
pp. 2801-2808 ◽  
Author(s):  
Philippe Joly ◽  
Pierre-Alain Falconnet ◽  
Janine André ◽  
Nicole Weill ◽  
Monique Reyrolle ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Legionella Pneumophila ◽  
Cooling Tower ◽  
Water System ◽  
Data Interpretation ◽  
Environmental Water ◽  
Hot Water ◽  
Rrna Gene ◽  
Conventional Culture

ABSTRACT Quantitative Legionella PCRs targeting the 16S rRNA gene (specific for the genus Legionella) and the mip gene (specific for the species Legionella pneumophila) were applied to a total of 223 hot water system samples (131 in one laboratory and 92 in another laboratory) and 37 cooling tower samples (all in the same laboratory). The PCR results were compared with those of conventional culture. 16S rRNA gene PCR results were nonquantifiable for 2.8% of cooling tower samples and up to 39.1% of hot water system samples, and this was highly predictive of Legionella CFU counts below 250/liter. PCR cutoff values for identifying hot water system samples containing >103 CFU/liter legionellae were determined separately in each laboratory. The cutoffs differed widely between the laboratories and had sensitivities from 87.7 to 92.9% and specificities from 77.3 to 96.5%. The best specificity was obtained with mip PCR. PCR cutoffs could not be determined for cooling tower samples, as the results were highly variable and often high for culture-negative samples. Thus, quantitative Legionella PCR appears to be applicable to samples from hot water systems, but the positivity cutoff has to be determined in each laboratory.

scholarly journals Lab Diagnosis of Legionnaires’ Disease

JMS SKIMS ◽  
2014 ◽  
Vol 17 (2) ◽  
pp. 50-54
Author(s):  
Nayeem U-Din Wani ◽  
Aamir Ali
Keyword(s):  
Legionella Pneumophila ◽  
Water System ◽  
Laboratory Diagnosis ◽  
Significant Rise ◽  
Control Measures ◽  
Causative Organism ◽  
Common Source ◽  
Contaminated Water ◽  
Atypical Pneumonia ◽  
Legionnaires Disease

Legionnaires’ disease is a multi-system disease which causes atypical pneumonia due to Legionella bacteria, most commonly of the species Legionella pneumophila. About one out of every 10 people who get sick from Legionnaires’ disease will die. Most common source of infection-contaminated water supply through inhalation of contaminated water droplets (aerosols). A laboratory diagnosis of Legionnaires’ disease can be made using a variety of laboratory tests including: culture/isolation of the causative organism, antigen detection in urine, a significant rise in antibody titres or PCR methods. Determination of the monoclonal subtype and molecular sequence typing can support linking between strains from the sampled environment and from patients. The control measures available to reduce the amount of Legionella in a water system include structural adaptations to the water system, temperature control, disinfection using chemicals or other oxidizing materials, and use of biocides or installation of filters. JMS 2014;17(2):50-54

scholarly journals Multiple Types of Legionella pneumophilaSerogroup 6 in a Hospital Heated-Water System Associated with Sporadic Infections

1999 ◽  
Vol 37 (7) ◽  
pp. 2189-2196 ◽  
Author(s):  
Paolo Visca ◽  
Paola Goldoni ◽  
P. Christian Lück ◽  
Jürgen H. Helbig ◽  
Lorena Cattani ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Water Samples ◽  
Water System ◽  
Hot Water ◽  
Control Measures ◽  
Hospital Environment ◽  
Modes Of Transmission ◽  
Sequence Of Events ◽  
Single Clone ◽  
Arbitrarily Primed Pcr

Five sporadic cases of nosocomial Legionnaires’ disease were documented from 1989 to 1997 in a hospital in northern Italy. Two of them, which occurred in a 75-year-old man suffering from ischemic cardiopathy and in an 8-year-old girl suffering from acute leukemia, had fatal outcomes. Legionella pneumophila serogroup 6 was isolated from both patients and from hot-water samples taken at different sites in the hospital. These facts led us to consider the possibility that a single clone of L. pneumophila serogroup 6 had persisted in the hospital environment for 8 years and had caused sporadic infections. Comparison of clinical and environmental strains by monoclonal subtyping, macrorestriction analysis (MRA), and arbitrarily primed PCR (AP-PCR) showed that the strains were clustered into three different epidemiological types, of which only two types caused infection. An excellent correspondence between the MRA and AP-PCR results was observed, with both techniques having high discriminatory powers. However, it was not possible to differentiate the isolates by means of ribotyping and analysis of rrnoperon polymorphism. Environmental strains that antigenically and chromosomally matched the infecting organism were present at the time of infection in hot-water samples taken from the ward where the patients had stayed. Interpretation of the temporal sequence of events on the basis of the typing results for clinical and environmental isolates enabled the identification of the ward where the patients became infected and the modes of transmission of Legionellainfection. The long-term persistence in the hot-water system of different clones of L. pneumophila serogroup 6 indicates that repeated heat-based control measures were ineffective in eradicating the organism.

scholarly journals Environmental Surveillance of Legionellosis within an Italian University Hospital—Results of 15 Years of Analysis

2019 ◽  
Vol 16 (7) ◽  
pp. 1103 ◽  
Author(s):  
Pasqualina Laganà ◽  
Alessio Facciolà ◽  
Roberta Palermo ◽  
Santi Delia
Keyword(s):  
Potential Risk ◽  
Legionella Pneumophila ◽  
Water Samples ◽  
Continuous Monitoring ◽  
Water System ◽  
Hot Water ◽  
University Hospital ◽  
Environmental Surveillance ◽  
Standard Procedures ◽  
Legionnaires Disease

Legionnaires’ disease is normally acquired by inhalation of legionellae from a contaminated environmental source. Water systems of large and old buildings, such as hospitals, can be contaminated with legionellae and therefore represent a potential risk for the hospital population. In this study, we demonstrated the constant presence of Legionella in water samples from the water system of a large university hospital in Messina (Sicily, Italy) consisting of 11 separate pavilions during a period of 15 years (2004–2018). In total, 1346 hot water samples were collected between January 2004 and December 2018. During this period, to recover Legionella spp. from water samples, the standard procedures reported by the 2000 Italian Guidelines were adopted; from May 2015 to 2018 Italian Guidelines revised in 2015 (ISS, 2015) were used. Most water samples (72%) were positive to L. pneumophila serogroups 2–14, whereas L. pneumophila serogroup 1 accounted for 18% and non-Legionella pneumophila spp. Accounted for 15%. Most of the positive samples were found in the buildings where the following critical wards are situated: (Intensive Care Unit) ICU, Neurosurgery, Surgeries, Pneumology, and Neonatal Intensive Unit Care. This study highlights the importance of the continuous monitoring of hospital water samples to prevent the potential risk of nosocomial legionellosis.

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

1987 ◽  
Vol 98 (3) ◽  
pp. 253-262 ◽  
Author(s):  
C. D. Ribeiro ◽  
S. H. Burge ◽  
S. R. Palmer ◽  
J. O'H. Tobin ◽  
I. D. Watkins
Keyword(s):  
Monoclonal Antibody ◽  
Legionella Pneumophila ◽  
Water Samples ◽  
Water System ◽  
Extended Period ◽  
Control Measures ◽  
Nosocomial Outbreak ◽  
Water Supplies ◽  
Chemical Sterilization ◽  
Legionnaires Disease

SUMMARYSwabs 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.

Hospital Characteristics Associated With Colonization of Water Systems byLegionellaand Risk of Nosocomial Legionnaires' Disease: A Cohort Study of 15 Hospitals

1999 ◽  
Vol 20 (12) ◽  
pp. 798-805 ◽  
Author(s):  
Jacob L. Kool ◽  
David Bergmire-Sweat ◽  
Jay C. Butler ◽  
Ellen W. Brown ◽  
Deborah J. Peabody ◽  
...  
Keyword(s):  
Drinking Water ◽  
San Antonio ◽  
Water System ◽  
Water Systems ◽  
Hot Water ◽  
Control Measures ◽  
Chlorine Concentration ◽  
Urinary Antigen ◽  
Legionnaires Disease ◽  
Antigen Tests

AbstractObjective:To investigate an increase in reports of legionnaires' disease by multiple hospitals in San Antonio, Texas, and to study risk factors for nosocomial transmission of legionnaires' disease and determinants forLegionellacolonization of hospital hot-water systems.Setting:The 16 largest hospitals in the cities of San Antonio, Temple, and Austin, Texas.Design:Review of laboratory databases to identify patients with legionnaires' disease in the 3 years prior to the investigation and to determine the number of diagnostic tests forLegionellaperformed; measurement of hot-water temperature and chlorine concentration and culture of potable water forLegionella. Exact univariate calculations, Poisson regression, and linear regression were used to determine factors associated with water-system colonization and transmission ofLegionella.Results:Twelve cases of nosocomial legionnaires' disease were identified; eight of these occurred in 1996. The rise in cases occurred shortly after physicians started requestingLegionellaurinary antigen tests. Hospitals that frequently usedLegionellaurinary antigen tests tended to detect more cases of legionnaires' disease.Legionellawas isolated from the water systems of 11 of 12 hospitals in San Antonio; the 12th had just experienced an outbreak of legionnaires' disease and had implemented control measures. Nosocomial legionellosis cases probably occurred in 5 hospitals. The number of nosocomial legionnaires' disease cases in each hospital correlated better with the proportion of water-system sites that tested positive forLegionella (P=.07) than with the concentration ofLegionellabacteria in water samples (P=.23). Hospitals in municipalities where the water treatment plant used monochloramine as a residual disinfectant (n=4) and the hospital that had implemented control measures wereLegionella-free. The hot-water systems of all other hospitals (n=11) were colonized withLegionella. These were all supplied with municipal drinking water that contained free chlorine as a residual disinfectant. In these contaminated hospitals, the proportion of sites testing positive was inversely correlated with free residual chlorine concentration (P=.01). In all hospitals, hot-water temperatures were too low to inhibitLegionellagrowth.Conclusions:The increase in reporting of nosocomial legionnaires' disease was attributable to increased use of urinary antigen tests; prior cases may have gone unrecognized. Risk of legionnaires' disease in hospital patients was better predicted by the proportion of water-system sites testing positive forLegionellathan by the measured concentration ofLegionellabacteria. Use of monochloramine by municipalities for residual drinking water disinfection may help prevent legionnaires' disease.

scholarly journals Local adaptation of Legionella pneumophila within a hospital hot water system increases tolerance to copper

2020 ◽  
Author(s):  
Emilie Bédard ◽  
Hana Trigui ◽  
Jeffrey Liang ◽  
Margot Doberva ◽  
Kiran Paranjape ◽  
...  
Keyword(s):  
Local Adaptation ◽  
Legionella Pneumophila ◽  
Cooling Tower ◽  
Water System ◽  
Healthcare Facility ◽  
Water Systems ◽  
Hot Water ◽  
Environmental Stressors ◽  
Large Building ◽  
Tolerance To Copper

AbstractIn large-building water systems, Legionella pneumophila is exposed to common environmental stressors such as copper. The aim of this study was to evaluate the susceptibility to copper of L. pneumophila isolates recovered from various sites: two clinical and seven environmental from hot water systems biofilm & water, and from cooling tower water. After one-week acclimation in simulated drinking water, strains were exposed to various copper concentrations (0.8 to 5 mg/L) for over 672 hours. Complete loss of culturability was observed for three isolates, following copper exposure to 5 mg/L for 672h. Two ST1427-like isolates were highly sensitive to copper, while the other two, isolated from biofilm samples, were resistant. The expression of the copper resistance gene copA evaluated by RT-qPCR was significantly higher for the biofilm isolates. All four ST1427-like isolates were recovered from the same water system during an outbreak. Whole genome sequencing results confirmed that the four isolates are very close phylogenetically, differing by only 29 single nucleotide polymorphisms, suggesting in situ adaptation to microenvironmental conditions, possibly due to epigenetic regulation. These results indicate that the immediate environment within a building water distribution system influences the tolerance of L. pneumophila to copper. Increased contact of L. pneumophila biofilm strains with copper piping or copper alloys in the heat exchanger might lead to local adaptation. The phenotypic differences observed between water and biofilm isolates from the hot water system of a healthcare facility warrants further investigation to assess the relevance of evaluating disinfection performances based on water sampling alone.ImportanceLegionella pneumophila is a pathogen indigenous to natural and large building water systems in the bulk and the biofilm phases. The immediate environment within a system can impact the tolerance of L. pneumophila to environmental stressors, including copper. In healthcare facilities, copper levels in water can vary, depending on water quality, plumbing materials and age. This study evaluated the impact of the isolation site (water vs biofilm, hot water system vs cooling tower) within building water systems. Closely related strains isolated from a healthcare facility hot water system exhibited variable tolerance to copper stress shown by differential expression of copA, with biofilm isolates displaying highest expression and tolerance. Relying on the detection of L. pneumophila in water samples following exposure to environmental stressor such as copper may underestimate the prevalence of L. pneumophila, leading to inappropriate risk management strategies and increasing the risk of exposure for vulnerable patients.

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