July 13, 2021
By Zeina A. Kanafani, MD, MS, FIDSA
Fluoroquinolone-based regimens are commonly used for the treatment of diverticulitis in the outpatient setting. However, safety concerns have prompted a directive from the U.S. Food and Drug Administration not to use fluoroquinolones except when no alternative treatment options are available. A recent paper in Annals of Internal Medicine by Gaber et al. compared the effectiveness and safety of amoxicillin-clavulanate to a metronidazole-fluoroquinolone combination in adult patients with diverticulitis treated as outpatients. They analyzed retrospectively two nationwide cohort studies based on two data sources, the IBM MarketScan Commercial Claims and Encounters Database (IBM Watson Health) and Medicare.
In the MarketScan database, the study identified 106,361 subjects who had received a metronidazole-fluoroquinolone combination and 13,160 subjects who had received amoxicillin-clavulanate. All outcome measures were similar in both treatment groups: 1-year admission risk (risk difference, 0.1%; 95% confidence interval [CI], -0.3 to 0.6), 1-year urgent surgery risk (risk difference, 0%; 95% CI, -0.1 to 0.1), 3-year elective surgery risk (risk difference, 0.2%; 95% CI, -0.3 to 0.7), and 1-year C. difficile infection risk (risk difference, 0%; 95% CI, -0.1 to 0.1). From the Medicare database, a 10% sample was analyzed, with 17,639 subjects in the metronidazole-fluoroquinolone arm and 2,709 subjects in the amoxicillin-clavulanate arm. Similar to results from the first cohort, the 1-year admission risk, 1-year urgent surgery risk, and 3-year elective surgery risk were not statistically significant between amoxicillin-clavulanate and metronidazole-fluoroquinolone treatment. As for the 1-year C. difficile infection risk, it was statistically higher with metronidazole-fluoroquinolone than with amoxicillin-clavulanate treatment (risk difference, 0.6%; 95% CI, 0.2 to 1.0).
These data suggest that a regimen consisting of a narrow-spectrum antimicrobial agent such as amoxicillin-clavulanate is safer and equally effective compared to metronidazole-fluoroquinolone combination therapy.