Fecal Colonization with ESBL-Producing E. coli and Risk for UTIs

Gram-negative gut bacteria — Escherichia coli — constitute the reservoir from which urinary tract infections (UTIs) originate. The prevalence of extended-spectrum β-lactamase–producing E. coli (ESBL–E. coli) has recently increased in UTI isolates. Now, researchers in France have investigated the association between the relative abundance of ESBL–E. coli in feces (fecal ESBL-RA) and the occurrence of ESBL–E. coli UTIs. The study involved 310 women from four southern European countries with high ESBL–E. coli prevalence who presented to outpatient clinics with symptoms suggesting a UTI, and who, in addition to a urine sample, provided a stool sample for microbiological analysis.

The overall prevalence of ESBL–E. coli fecal carriage was 20.3%. ESBL–E. coli UTIs were present in 12.3% of the women. The mean fecal ESBL-RA was 13-fold higher in women with antibiotic exposure at the time of sampling than in those not exposed (14.3% vs. 1.1%; P<0.001). Similarly, the ESBL-RA was 18-fold higher in women with ESBL–E. coli UTIs than in those with non-ESBL–E. coli UTIs (10.0% vs. 0.56%; P<0.05). An ESBL-RA <0.1% was 100% predictive of a non-ESBL–E. coli UTI. The virulence factors of fecal ESBL–E. coli had no influence on their propensity to cause UTIs.