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: 2.67-73 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. © 2008 Cambridge University Press.
Garcia-Nuñez, M., Pedro-Botet, M. L., Ragull, S., Sopena, N., Morera, J., Rey-Joly, C., & Sabria, M. (2009). Cytopathogenicity and molecular subtyping of Legionella pneumophila environmental isolates from 17 hospitals. Epidemiology and Infection, 137(2), 188-193. https://doi.org/10.1017/S0950268808000691