Biochemical characteristics, phage patterns, and O1 factor analysis of Escherichia coli O1:K1:H7:F11 and O1:K1:H-:F9 strains isolated from patients with urinary tract infections.

Biochemical characteristics, O1 antigen factors and phage patterns were examined in 35 urinary O1:K1 isolates of Escherichia coli different in H and F antigen. Fermentation of dulcitol, decarboxylation of ornithine, requirement for nicotinamide, and determination of O1 factor d allowed maximum differentiation. On the basis of these tests the strains could be divided into two major groups which are obviously of different clonal origin. Members of clone 1 represented by serotypes O1:K1:H7:F11 (12 strains) and O1:K1:H-:F11 (5 strains) were characterized by positive biochemical reactions and absence of O1 antigen factor d. Negative biochemical tests and presence of O1 antigen factor d were shown by strains of clone 2 which were of serotypes O1:K1:H-:F9 (14 strains) and O1:K1:H-:F- (3 strains). Phage patterns are less well correlated with clonal assignment. However, strains of clone 2 were not susceptible to K1-specific phage D and were non-typable with another set of 13 phages.