Geographical distribution of antimicrobial resistance among Escherichia coli causing acute uncomplicated pyelonephritis in the United States.

The susceptibility to 12 antimicrobial agents of 165 Escherichia coli isolates from women with acute uncomplicated pyelonephritis of mild to moderate severity was analyzed by geographic region in the US. Ampicillin, trimethoprim, and trimethoprim/sulfamethoxazole resistance exhibited a descending prevalence gradient from west to east. Composite antimicrobial resistance phenotypes also exhibited significant regional differences, with a greater prevalence of most combined resistance profiles seen in the Pacific region of the US, but with significant north-south variation for combined ampicillin/sulfisoxazole resistance. These findings suggest geographical segregation of resistant clones and/or resistance elements among uropathogenic E. coli within the US, which is relevant both to clinical practice and to understanding the basis for the current epidemic of antimicrobial resistance in E. coli.