Predictive utility of prior positive urine cultures
Abstract
BACKGROUND: A patient's prior urine cultures are often considered when choosing empiric antibiotic therapy for a suspected urinary tract infection. We sought to evaluate how well previous urine cultures predict the identity and susceptibility of organisms in a patient's subsequent urine cultures.
METHODS: We conducted a multinational, multicenter, retrospective cohort study, including 22 019 pairs of positive urine cultures from 4351 patients across 2 healthcare systems in Toronto, Ontario, and Chicago, Illinois. We examined the probability of the same organism being identified from the same patient's positive urine culture as a function of time elapsed from the previous positive urine specimen; in cases where the same organism was identified we also examined the likelihood of the organism exhibiting the same or better antimicrobial susceptibility profile.
RESULTS: At 4-8 weeks between cultures, the correspondence in isolate identity was 57% (95% confidence interval [CI], 55%-59%), and at >32 weeks it was 49% (95% CI, 48%-50%), still greater than expected by chance (P 32 weeks, still greater than expected by chance (P < .001). Despite high local rates of ciprofloxacin resistance in urine isolates across all patients (40%; 95% CI, 39.5%-40.5%), ciprofloxacin resistance was <20% among patients with a prior ciprofloxacin sensitive organism and no subsequent fluoroquinolone exposure.
CONCLUSIONS: A patient's prior urine culture results are useful in predicting the identity and…
How strong is the evidence?
Evidence Hub reads this as a cohort study, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 4,351 participants or records.
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