LAUSR

OBJECTIVES The bacterial features associated with recurrent urinary tract infections (RUTIs) due to extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-E. coli) are not well-understood. We investigated phylogenetic groups and ST131 subclones to assess strain homology of ESBL-E. coli isolates in patients with RUTIs from the in- and out-patient setting in western Sweden. METHODS Almost all (319/356) isolates from 123 patients with 2-7 episodes (median 2) of ESBL-E. coli UTI within 1 year were examined for seven E. coli phylogroups, the ST131-O25b clone, and its subclone fimH30Rx. Antibiotic resistance and ESBL-genes were determined for the index isolates. A subset of isolates was typed using pulsed-field gel electrophoresis. RESULTS The same phylogroup and ST131 subclones were seen for all recurrences in 119/123 patients and PFGE confirmed strain homology in recurrences for 43/44 patients tested. Phylogroup B2 dominated (56%), followed by D (19%) and F (10%). ST131-O25b and fimH30Rx isolates were detected in 44% and 30%, respectively. CTX-M group 1 (71%) predominated. Elderly patients were in majority. There were no associations between patient demographics or time to recurrence and bacterial characteristics. The fimH30Rx subclone was associated with a higher number of recurrences (p = 0.015) as compared to the remaining B2 isolates. CONCLUSIONS In ESBL-E. coli RUTI, most recurrences were caused by the initial infecting strain. The high frequency of the multidrug-resistant fimH30Rx subclone and its association with multiple recurrences warrants further attention and early detection of this subclone in patients at risk of developing RUTI with ESBL-producing E. coli.