Cytopathogenicity and molecular subtyping of Legionella pneumophila environmental isolates from 17 hospitals

• Published in: Epidemiology and infection 2009-02, Vol.137 (2), p.188-193
• Main Authors: GARCIA-NUÑEZ, M., PEDRO-BOTET, M. L., RAGULL, S., SOPENA, N., MORERA, J., REY-JOLY, C., SABRIA, M.
• Format: Article
• Language: English
• Subjects: Bacteria; Bacterial Typing Techniques; Bacteriology; Biological and medical sciences; Cell Line; DNA Fingerprinting; DNA, Bacterial - genetics; Electrophoresis, Gel, Pulsed-Field; Environmental disorders; Environmental Microbiology; Epidemiology; Fundamental and applied biological sciences. Psychology; Genotype; Hospitals; Humans; Infections; Infectious diseases; Legionella; Legionella pneumophila; Legionella pneumophila - classification; Legionella pneumophila - genetics; Legionella pneumophila - isolation & purification; Legionella pneumophila - pathogenicity; Legionnaire's disease; Legionnaires disease; Macrophages - microbiology; Microbiology; Miscellaneous; Pneumonia and Respiratory Infections; Serotyping; Virulence; Water distribution; Water distribution systems; Water pollution
• ISSN: 0950-2688; 1469-4409
• DOI: 10.1017/S0950268808000691

The cytopathogenicity of 22 Legionella pneumophila isolates from 17 hospitals was determined by assessing the dose of bacteria necessary to produce 50% cytopathic effect (CPED50) in U937 human-derived macrophages. All isolates were able to infect and grow in macrophage-like cells (range log10 CPED50: 2·67–6·73 c.f.u./ml). Five groups were established and related to the serogroup, the number of PFGE patterns coexisting in the same hospital water distribution system, and the possible reporting of hospital-acquired Legionnaires' disease cases. L. pneumophila serogroup 1 isolates had the highest cytopathogenicity (P=0·003). Moreover, a trend to more cytopathogenic groups (groups 1–3) in hospitals with more than one PFGE pattern of L. pneumophila in the water distribution system (60% vs. 17%) and in hospitals reporting cases of hospital-acquired Legionnaires' disease (36·3% vs. 16·6%) was observed. We conclude that the cytopathogenicty of environmental L. pneumophila should be taken into account in evaluating the risk of a contaminated water reservoir in a hospital and hospital acquisition of Legionnaires' disease.