CHARACTERIZATION OF URINARY ESCHERICHIA-COLI O75 STRAINS

Forty-four Escherichia coli O75 strains from patients with urinary tra ct infections were characterized by a variety of methods to obtain evi dence of their clonal distribution and uropathogenic properties. By K and H antigen typing, the strains were divided into the following sero types: O75:K5:H- (18 strains), O75:K95:H- (10 strains), O75:K95:H5 (7 strains), O75:K100:H5 (4 strains), and O75:K-:H55 (5 strains). General ly, biotyping proved to be of no discriminative value. With two except ions the strains were found to be sensitive to the bactericidal effect of normal human serum. As shown by multilocus enzyme electrophoresis, the whole-cell protein profile (WCPP), and the patterns of the outer membrane proteins and lipopolysaccharides, all but the five O75:H55 st rains were genetically closely related to each other and could be clas sified into one clonal group. The O75:K-:H55 strains proved to be quit e different and lacked type 1 fimbriae. All 17 K95 (H-, H5) strains pr oduced hemolysin and P fimbriae. Five of the O75:K5:H- strains were di fferent from the other K5 strains by showing hemagglutinating properti es, on the basis of the presence of the OX adhesin. The last two group s are suggested to be uropathogenic and are proposed to represent sepa rate clonal groups or subgroups.