Six widespread bacterial clones among Escherichia coli K1 isolates

Abstract

Variable properties among E. coli isolates include serotype, electrophoretic migration of major outer membrane proteins, metabolic properties, production of hemolysin or colicin or both, and plasmid content. These characteristics were compared in E. coli strains of capsular types K1, K5, K92 and K100 and in non-encapsulated isolates. The 234 bacterial strains from the USA and Europe studied were isolated from healthy or diseased individuals recently or as long ago as 1941. Regardless of source, most O7:K1, O16:K1 and O75:K100 isolates could be assigned to 3 unique, serotype-specific groups, which were interpreted as representing 3 bacterial clones. Two bacterial (sub)clones each were discerned among the O18:K1 and O18:K5 isolates and 2 further, distinct clones were discerned among the O1:K1 isolates. The implications of these results for epidemiological analyses and for virulence are discussed.