Efficacy, Safety, and in vitro Sensitivity of Omadacycline in the Treatment of Brucellosis: A Case Series Study

Purpose: Treatment options for brucellosis are limited. Omadacycline demonstrates strong antibacterial activity against a broad spectrum of bacteria. However, the efficacy of omadacycline against Brucella spp. remains unclear. Patients and Methods: We screened brucellosis patients who received omadacycline from April to July 2023 across five hospitals in China and conducted in vitro experiments to evaluate the activity of omadacycline against different Brucella species. Results: A total of 13 patients were included, all of whom received omadacycline as part of a combination regimen. Within this cohort, 11 were diagnosed with Brucella spondylitis, and 8 of these underwent surgical intervention. Omadacycline was administered as second-line therapy in 10 (76.9%) patients due to uncontrolled symptoms and as empirically in the remaining 3. Following the initiation of an omadacycline-containing regimen, symptoms of fever and/or back pain improved rapidly, regardless of whether it was used as empirical or second-line therapy. The median time from omadacycline initiation to defervescence was 3 days, and to relief of back pain was 7 days. The median duration of omadacycline treatment was 32 days, and it was administered in combination with other agents, including rifampicin and cephalosporins. The regimen was well tolerated, with only one patient experiencing mild nausea. In vitro, omadacycline demonstrated consistent activity against all tested Brucella species. Conclusion: In this case series, omadacycline-containing regimens were well tolerated and associated with rapid symptomatic improvement. These findings support further evaluation in prospective comparative studies. Keywords: Brucella , brucellosis, omadacycline, case series, susceptibility