A disseminated multidrug-resistant clonal group of uropathogenic Escherichia coli in pyelonephritis

In acute pyelonephritis, bacterial resistance to cotrimoxazole predicts treatment failure, but the clonal basis of such resistance is undefined. We did molecular and serological analyses of 170 Escherichia coli urine isolates obtained in 1994–96 from women with acute pyelonephritis. 12 (7%) of the pyelonephritis isolates were in clonal group A (CGA; responsible for 38–51% of co-trimoxazole resistance in acute cystitis), including ten (34%) of 29 isolates that were resistant to co-trimoxazole. CGA isolates were obtained from diverse locations across the USA and were related to the 015:K52:H1 clone of the 1986–87 outbreak in London, UK. Thus, CGA is broadly disseminated and contributes to co-trimoxazole resistance in pyelonephritis as well as in cystitis.