Genotypic and Phenotypic Methods for the Investigation of a Nosocomial Legionella pneumophila Outbreak and Efficacy of Control Measures

• Published in: The Journal of infectious diseases Vol. 166; no. 1; pp. 22 - 30
• Main Authors: Struelens, Marc J., Maes, Nicole, Rost, Francis, Deplano, Ariane, Jacobs, Frédérique, Liesnard, Corinne, Bornstein, Nicole, Grimont, Francine, Lauwers, Sabine, McIntyre, Michael P., Serruys, Elisabeth
• Format: Journal Article
• Language: English
• Published: Chicago, IL The University of Chicago Press 01-07-1992; University of Chicago Press
• Subjects: Belgium - epidemiology; Biological and medical sciences; Cross Infection - epidemiology; Cross Infection - microbiology; Cross Infection - prevention & control; Disease Outbreaks; Disinfection; Epidemics; Epidemiology; Genotype; Humans; Immune Tolerance; Infections; Infectious diseases; Legionella; Legionella pneumophila; Legionella pneumophila - classification; Legionellosis; Legionnaires disease; Legionnaires' Disease - epidemiology; Legionnaires' Disease - microbiology; Legionnaires' Disease - prevention & control; Major Articles; Medical sciences; Phenotype; Restriction Mapping; Retrospective Studies; Serotyping; Water Microbiology; Water pollution; Water Supply - standards; Belgium; Water; Antibody; Serogroup; Exploration; Parasitosis; Medical screening; Contamination; Result; Infection; Spectrometry; Immunological investigation; Bacteriosis; Evolution; Diagnosis; Technique
• ISSN: 0022-1899; 1537-6613
• DOI: 10.1093/infdis/166.1.22

To determine the source of a nosocomial outbreak of Legionella pneumophila serogroup 1 infection and the efficacy of control measures, clinical and environmental isolates were characterized by molecular subtyping and disease surveillance was conducted. The outbreak involved 32 cases (relative risk, 4.0; P < .001 vs. previous period). Water colonization with L. pneumophila serogroup 1 and patients' exposure to faucet use incriminated the water system as the environmental source. Monoclonal antibody typing showed that patient isolates belonged mainly to type Pontiac and water isolates mainly to type Bellingham (P < .001). By four genotypic techniques, outbreak-related isolates from patients and the water system were found to be clonally related and distinct from control strains (P < .001). Heat and UV light treatment of the water system showed a protective efficacy of 88% (95% confidence interval, 75%–94%). These findings indicate that phenotypic variation may interfere with monoclonal antibody typing of legionellae and that waterborne legionellosis can be controlled by physical disinfection.