Phenotypic variation amongst genotypically homogeneousLegionella pneumophilaserogroup 1 isolates: implications for the investigation of outbreaks of Legionnaires' disease

Abstract

SUMMARYOne hundred and seventy-nine isolates ofLegionella pneumophilaserogroup 1, obtained from a site associated with an outbreak of Legionnaires' disease, were examined by monoclonal antibody subgrouping, restriction fragment length polymorphism typing, restriction endonuclease analysis and plasmid content. Nine distinct phenotypes were detected but at the genotypic level all strains were closely related. The data presented indicate that phenotypic variation of a single parent strain can occur within an environmental site. The implications of these findings are discussed in relation to the investigation of outbreaks of Legionnaires' disease.