Recurrence of urinary tract infections in adult patients with community-acquired pyelonephritis caused by E. coli: a 1-year follow-up.

In a prospective study, 42 women were followed for recurrence of urinary tract infections (UTIs) for 1 y after an index episode of community-acquired pyelonephritis caused by Escherichia coli. Altogether, 26 repeat episodes were detected. Of these, 20 occurred at least 1 month after the index episode and were regarded as recurrences. In all, 40%, (17 of 42) of the women had recurrences. An earlier history of UTI increased the risk of recurrence: 52%, of the 29 women with previous UTI had at least 1 recurrence, compared with 15%, of the 13 patients without previous UTI. E. coli caused the majority (73%) of the recurrences. Genotype comparisons by RAPD-PCR analysis between E. coli isolates from a patient showed that 75%. of the original and recurrent strains were genetically non-identical. Of the 54 E. coli strains, 42 were carrying genes coding for G adhesins of P fimbriae: 40 isolates carried class II, I class III and 1 carried both class II and III G adhesin genes. Each of the virulence-associated factors (genes for G adhesins, MRHA, haemolysin, type 1C fimbriae, and O and K antigens) was evenly distributed among E. coli isolates of index episodes, independent of the recurrences. The index isolates, however, had more virulence-associated factors than did the isolates from the recurrences which were mainly due to lower UTIs.