Serological Grouping of Urinary Escherichia Coli.

Using only 12 antisera it has been possible to group 56.6% of all strains. Forty-four per cent of all strains were typable in the first eight of the serological groups used. Of the primary isolates from symptomatic infections, 65.7% were typable; 48.6% of all strains of the serological groups 01, 02, 04, and 06 occurred in these primary symptomatic isolates. There was a good correlation in the serological typing of five colonies isolated from the initial isolation plates. There was complete agreement in all the typable strains, 325 of the 350 colonies. Twenty-five strains were not typable due to roughness. It is considered that this reproducibility confirms the validity of using one colony for serotyping of urinary isolates. Statistically there was no significant difference in the number of typable strains from specimens with high bacterial counts and specimens with low bacterial counts. Nor was there any difference in frequency of the typability of strains in patients with primary symptomatic infection compared with those with associated urinary tract abnormalities. There was a possibly significant increased frequency of typable strains in the primary infection compared with the recurrent infection. There was no significant difference in the frequency of specific serological groups in the high and low bacterial count groups. There was no statistical difference in the frequency of individual serological groups isolated from the two sexes.