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Chapter 52 : Typing of Legionella Strains Isolated from Patients and Environmental Sources in Germany, 1999–2000
Legionella spp. are gram-negative bacteria responsible for epidemic and sporadic cases of pneumonia after inhalation of contaminated water droplets from a variety of water sources. This chapter presents the distribution of Legionella species, serogroups, and monoclonal subtypes of Legionella strains isolated in Germany and typed at the National Reference Laboratory for Legionella. Environmental strains were isolated on selective buffered charcoal-yeast extract agar from water samples collected at various locations in Germany. The monoclonal subtypes were named according to the reactivity with reference strains. For macrorestriction analysis, chromosomal DNAs were digested overnight with SfiI, AscI, and Notl (New England Biolabs, Schwahlbach, Germany) and separated with the CHEF III System (BioRad Laboratories, Munich, Germany). In this study, all patients had a radiographically confirmed pneumonia confirmed as legionellosis by isolating a Legionella strain from clinical specimens. Cases were classified as nosocomial if the patient had been hospitalized continuously for a minimum of 3 days at the time of disease onset or had been discharged from the hospital less than 10 days before the onset of symptoms. Of the 133 strains grown from clinical samples, 88 (66%) belonged to serogroup 1, 38 (29%) belonged to serogroups 2 to 15, and 7 (5%) were typed as other Legionella species. These data are in good agreement with results from Europe and the United States.