Prevalence and risk factors for trimethoprim–sulfamethoxazole-resistant Escherichia coli among women with acute uncomplicated urinary tract infection in a developing country

• Escherichia coli resistance to trimethoprim–sulfamethoxazole (TMP–SMX) was high (41%) and unaffected by prior antibiotic use.
• The number of urinary tract infection episodes in the past year was associated with TMP–SMX resistance.
• Resistance to fluoroquinolones, cephalosporins, and nitrofurantoin was rare (<7%).
• Overall resistance rates were much lower than laboratory-based surveillance antibiograms.

SummaryBackgroundProspective studies from developing countries that have investigated risk factors for trimethoprim–sulfamethoxazole (TMP–SMX)-resistant Escherichia coli in women with uncomplicated urinary tract infection (UTI) remain scarce.MethodsWomen with acute uncomplicated UTI were enrolled prospectively. Urine was sent for antimicrobial susceptibility testing. Logistic regression analysis was used to identify risk factors for TMP–SMX resistance.ResultsOf 405 participants, 229 (56.5%) had bacteriuria (mean age 31.9 ± 9.5 years). In the previous 12 months, 77 (33.6%) had experienced at least one UTI episode and 106 (46.3%) reported antimicrobial use. The most common uropathogens were E. coli (75.8%) and Staphylococcus saprophyticus (8.9%). For the 179 E. coli, resistance rates were highest for ampicillin (64.3%) and TMP–SMX (41.3%). Resistance to cephalosporins, nitrofurantoin, and fluoroquinolones was much lower compared with the hospital laboratory-based surveillance data. Risk factors for TMP–SMX resistance were UTI in the last 6 months (odds ratio 2.22; p = 0.04) and the number of UTI episodes in the past year (odds ratio 2.06; p = 0.004). The number of UTI episodes (adjusted odds ratio 2.21; p = 0.02) remained significant on multivariate analysis.ConclusionsTMP–SMX resistance was high. Number of previous UTI episodes was associated with increased risk of resistance; prior antimicrobial use was not. Hospital antibiograms should be used with caution when treating uncomplicated UTI.