Clonal distribution of K1 and K5 antigen possessing Escherichia coli isolates.

A significant difference was observed in the occurrence of the examined markers (Col+, ColV+, Hly+, Aer+, AbR) and in the plasmid carrier state between strains with and without K1 and K5 antigens. Plasmids of the same size were harboured by serotypes possessing K1 and K5 antigens, e.g. among O1: K1: H- strains plasmids of 60-79 Md, among O1: K1: H7, O18ac: K1: H7, O45: K1: H7 and O83: K1: H- strains plasmids of 80-95 Md were frequent. The average plasmid number was higher in K1 strains than in K5 strains. In serogroup O1 the frequency of the plasmid carrier state was associated with the O serogroup and not with the K antigen. The plasmid number in K5 of serogroups O6 and O18 was lower than in K5- strains. Plasmids of 80-95 Md were predominant among the strains derived from blood and cerebrospinal fluid, whereas these plasmids were rare among the K1 and K5 strains isolated from other sources. Plasmids of 60-79 Md were frequent among strains derived from different sources. The 30-40 Md plasmids were relatively frequent among strains isolated from urine. In contrast with literary data, O1: K1: H-, O1: K1: H7 and other frequent serotypes consisted of different clones. Different clones were found within a single serotype, too.