Multidrug-resistant Escherichia coli clonal groups causing community-acquired pyelonephritis

From October 1999 through January 2000, an Escherichia coli clonal group ( designated "CgA") was isolated from the urine of nearly one-half of all women with urinary tract infections (UTIs) caused by trimethoprim-sulfamethoxazole (TMP-SMZ)-resistant E. coli in a California community. This study describes the prevalence of pyelonephritis caused by CgA in the same community. E. coli isolates were characterized by enterobacterial repetitive intergenic consensus (ERIC2) polymerase chain reaction (PCR), serogrouping, and pulsed-field gel electrophoresis. Fourteen (11%) of 130 women with UTIs received a diagnosis of pyelonephritis. CgA was associated with 4 (57%) of the 7 pyelonephritis cases caused by TMP-SMZ - resistant E. coli and was associated with none of the cases caused by TMP-SMZ - susceptible E. coli (P<.02). Six (86%) of these TMP-SMZ-resistant E. coli isolates belonged to 2 distinct ERIC2 PCR - defined clonal groups, whereas all of the TMP-SMZ susceptible E. coli strains had unique fingerprints (P<.001). The prevalence of antimicrobial-resistant pyelonephritis in a community may be affected by a limited number of E. coli clonal groups.