N Engl J Med
Ciprofloxacin alone proves effective for bubonic plague
Study details: The multicenter, open-label, randomized, noninferiority IMASOY trial (NCT04110340) was conducted in Madagascar from 2020–2024. The study enrolled 450 patients with suspected bubonic plague, comparing two guideline-recommended regimens: 10 days of oral ciprofloxacin monotherapy vs. 3 days of injectable aminoglycoside followed by 7 days of oral ciprofloxacin. Primary endpoint was treatment failure by day 11, defined as death, persistent fever, secondary pneumonic plague, or need for alternative or extended treatment.
Results: Among 222 patients with confirmed or probable plague, ciprofloxacin monotherapy was noninferior to combination therapy. Treatment failure occurred in 9.0% of the ciprofloxacin group vs. 8.1% in the aminoglycoside–ciprofloxacin group (risk difference: 0.9 percentage points; 95% confidence interval –6.0 to 7.8). Mortality and rates of secondary pneumonic plague were similar between groups. Adverse events occurred in 18% to 19% of patients, with serious events in 5% to 7%.
Clinical impact: The findings support ciprofloxacin monotherapy as a viable first-line treatment for bubonic plague, especially in resource-limited settings. Its oral administration simplifies logistics and avoids aminoglycoside-related toxicity, offering a practical alternative for endemic regions and outbreak response.
Source:
Randremanana RV, et al; IMASOY Study Group. (2025, August 6). N Engl J Med. Ciprofloxacin versus Aminoglycoside-Ciprofloxacin for Bubonic Plague. https://pubmed.ncbi.nlm.nih.gov/40768716/