Omadacycline in the Treatment of Chlamydia psittaci Pneumonia: A Retrospective Study on Efficacy and Safety

Aims/Background Chlamydia psittaci is an obligate intracellular bacterium that primarily infects birds, but can cause respiratory infections in humans. Clinical evidence supporting the use of omadacycline for the treatment of Chlamydia psittaci pneumonia remains limited; therefore, this study aimed to evaluate the potential of omadacycline in treating Chlamydia psittaci pneumonia by analyzing the patients' clinical outcomes and the drug safety profile. Methods We retrospectively reviewed the medical records of 15 patients with Chlamydia psittaci pneumonia treated at the First Affiliated Hospital, Zhejiang University School of Medicine between January and December 2023. Following diagnosis with the aid of metagenomic next-generation sequencing, the patients received omadacycline for treatment, and their clinical outcomes and laboratory marker profiles were monitored to assess the treatment efficacy and safety. Results Significant improvements were observed in clinical symptoms and laboratory markers, including C-reactive protein (p < 0.001), procalcitonin (p = 0.001), neutrophil percentage (p < 0.001), and the SpO(2)/FiO(2 )ratio (p < 0.001), after treatment with omadacycline. A 100% cure rate was reported within 28 days of treatment initiation, with gastrointestinal disturbances being the most common side effect. Conclusion Omadacycline shows promise in treating Chlamydia psittaci pneumonia and is well tolerated by the users. However, further controlled trials involving larger samples are required to confirm the efficacy and safety of the drug.