- Use of extended-spectrum penicillins is associated with trimethoprim resistance in urinary tract infections (UTIs).
- The mechanism is unclear but may be due to selection by coresistance.
- Nitrofuran derivatives are associated with lower odds of trimethoprim resistance.
Why this matters
- Consider coresistance when prescribing antibiotics.
- Incorporate resistance testing into overall management for patients with recurrent UTIs.
- 1264 patients, 80.0% (1011) women; median age, 75.3 (range, 66.5-83.3) years.
- 31.1% (393) Escherichia coli isolates were trimethoprim-resistant.
- 70.6% (893) participants were prescribed ≥1 beta-lactam during the study period, including sulfonamide and trimethoprim (58.9%), fluoroquinolone (39.9%), nitrofurantoin (47.7%).
- >3 extended-spectrum penicillin prescriptions associated with trimethoprim resistance (OR, 1.68; 95% CI, 1.10-2.55).
- >3 trimethoprim/sulfonamide prescriptions significantly associated with trimethoprim resistance (OR, 2.22; P<.05>
- >3 nitrofurantoin prescriptions significantly associated with lower frequency of trimethoprim resistance (OR, 0.60; P<.05>
- Time since last extended-spectrum penicillin prescription associated with trimethoprim resistance (1-3 months; OR, 2.86; 95% CI, 1.29-6.34), except for penicillin/enzymes combinations.
- Nested case-control study evaluating effects of prior antimicrobial drug prescriptions on trimethoprim resistance in UTI among Rotterdam (the Netherlands) patients with E coli UTI.
- Funding: None disclosed.
- Adherence data missing.
- Residual confounding.
- Inability to confirm results by genetic association.