Distribution of R plasmids among the Q-antigen types of Escherichia coli isolated from various clinical sources.

A total of 655 Escherichia coli strains from various clinical sources were O-antigen typed, and the serological properties were correlated with R-plasmid carriage. Of the 655 strains, 224 were resistant to one or more antibiotics and 148 of these carried R plasmids. The distribution of O-antigen types among the susceptible strains was similar to that reported previously by others in England. The O-antigen types among the R(+) strains showed some similarities to those found in susceptible strains, but O-antigen types O8, O9, O17, O18 and, perhaps, O101 and O107 were more common in the R(+) than in the susceptible series. There is therefore some overlap between the O-antigen types of E. coli prevalent in R(+) strains from clinical cases and from human and animal fecal sources.