Community-acquired pyelonephritis in adults: characteristics of E. coli isolates in bacteremic and non-bacteremic patients.

Escherichia coli strains isolated from the urine in 49 consecutive episodes of community-acquired pyelonephritis in adult women were characterized for adhesins and hemolysin production. The mean age of the patients was 56 years and 47% had at least 1 compromising condition. P fimbriae was found in 67% and hemolysin production in 35% of the strains; these figures were significantly (p < 0.001) higher than the corresponding figures (11% for each) among 287 strains isolated from stool of healthy adults (Siitonen A. J Infect Dis 1992; 166: 1058-1065). The prevalence of Non-P mannose-resistant adhesins and type 1C fimbriae was low (4 and 8%, respectively) and did not differ significantly from the corresponding prevalences (1 and 7%) in healthy adults. 74% fo the pyelonephritic (but only 22% of the stool) isolates had at least 1 of these 4 virulence factors (p < 0.001) and 37% and 7%, respectively, had at least 2 (p < 0.001). Nevertheless, the strains represented a wide variety of O:K serotypes without any indication of specially virulent clones. Of the 49 patients 15 had concomitant bacteremia, and in all except 2 compromised elderly patients the urinary and blood isolates were identical.