The emergence of resistant Escherichia coli to fluoroquinolones (FQs) is of growing concern, yet the latest guidelines for the treatment of pyelonephritis still recommend FQs as first-line treatment. Our primary objective was to determine the impact of discordant prescribing of FQs in E coli pyelonephritis on hospital length of stay (LOS) and early clinical response (ECR).

We retrospectively compared discordant and concordant prescribing of FQs for LOS and ECR. We also compared FQs, ceftriaxone, piperacillin/tazobactam, and carbapenems for these clinical outcomes.

Forty-nine patients included in the comparison between discordant (n = 9) and concordant (n = 40) prescribing of FQs. There was significantly lower ECR in patients with discordant prescribing of FQs (38 of 40, 95% vs 5 of 9, 55.6%, P = .0074) and a trend toward longer LOS (4 [2.3] days vs 3 [2.0] days, P = .0571). Illness severity, estimated using Simplified Acute Physiology Score (SAPS II) score, was similar between groups (P = .717).

There was a significantly decreased ECR and a trend toward increased LOS when FQs were used in FQ-resistant E coli. Regarding alternative treatment for E coli pyelonephritis, ceftriaxone was as effective as concordant FQs and significantly better than discordant FQs.