[K antigen, colonization factor antigen, dulcitol fermentation, and hemolysin production in E. coli rough strains...

E. coli rough strains (as determined by spontaneous agglutination of in boiled saline suspension) isolated in significant amounts (>10(5)/ml) from from patients with urinary tract infections were investigated for some factors possibly related to virulence. The frequencies of capsular antigen, colonization factor antigen (CFA I), dulcitol fermentation, and hemolysin production are summarized in table 1. 270 (66.2%) out of 408 strains were found to be encapsulated as determined by the inagglutinability of the living strains in saline. 180 (44.1%) strains were able to ferment dulcitol, and evidence for hemolysin production could be demonstrated in 146 (35.8%) strains. The CFA I (demonstrated by a mannose resistant hemagglutination of human red blood cells) was detected in 62 (15.2%) of the E. coli rough strains tested. The frequency of single properties in the presence or absence of capsular antigen is shown in table 2 demonstrating no significant differences in both groups. The most frequent single factor was found to be the capsular antigen with 22.1%, followed by the double combination capsular antigen/dulcitol fermentation (16.7%), dulcitol fermentation alone (10%), and capsular antigen/hemolysin production (9.8%). There were only 5 strains possessing all four factors tested. On the other hand we found 35 (8.6%) rough strains with none of the properties. Some aspects of virulence of E. coli rough strains are discussed.