Reducing risk of

backgroundRisk of community-acquired

methodsWe conducted a nested case-control study at Kaiser Permanente Northern California, 2007-2010, to assess antibiotic prescribing and other factors in relation to risk of CA-CDI in outpatients with uncomplicated UTI. Cases were diagnosed with CA-CDI within 90 days of antibiotic use. We used matched controls and confirmed case-control eligibility through chart review. Antibiotics were classified as ciprofloxacin (most common), or low risk (nitrofurantoin, sulfamethoxazole/trimethoprim), moderate risk, or high risk (e.g. cefpodoxime, ceftriaxone, clindamycin) for CDI. We computed the adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the relationship of antibiotic treatment for uncomplicated UTI and history of relevant gastrointestinal comorbidity (including gastrointestinal diagnoses, procedures, and gastric acid suppression treatment) with risk of CA-CDI using logistic regression analysis.

resultsDespite the large population, only 68 cases were confirmed with CA-CDI for comparison with 112 controls. Female sex [81% of controls, adjusted odds ratio (OR) 6.3, CI 1.7-24), past gastrointestinal comorbidity (prevalence 39%, OR 2.3, CI 1.1-4.8), and nongastrointestinal comorbidity (prevalence 6%, OR 2.8, CI 1.4-5.6) were associated with increased CA-CDI risk. Compared with low-risk antibiotic, the adjusted ORs for antibiotic groups were as follows: ciprofloxacin, 2.7 (CI 1.0-7.2); moderate-risk antibiotics, 3.6 (CI 1.2-11); and high-risk antibiotics, 11.2 (CI 2.4-52).

conclusionsLower-risk antibiotics should be used for UTI whenever possible, particularly in patients with a gastrointestinal comorbidity. However, UTI can be managed through alternative approaches. Research into the primary prevention of UTI is urgently needed.