Efficacy and short-term safety of intravenous omadacycline as second-line therapy for macrolide- unresponsive Mycoplasma pneumoniae pneumonia in children: a retrospective cohort study.

OBJECTIVE

To evaluate the efficacy and short-term safety of omadacycline as second-line therapy for macrolide-unresponsive Mycoplasma pneumoniae pneumonia (MUMPP) in children aged 8-16 years.

METHODS

A total of 64 hospitalized children with MUMPP admitted between September 2023 and December 2024 were enrolled. Children with persistent fever (>38.0 °C) after 72 hours of azithromycin monotherapy were assigned to receive intravenous omadacycline (n=18) or continued azithromycin (n=46). Omadacycline was dosed according to body surface area (BSA)-based scaling from the approved adult regimen (loading dose on day 1; maintenance dose once daily for 7 days). Primary outcome: time to defervescence (TTD). Secondary outcomes: 72-hour defervescence rate, radiological improvement, corticosteroid use, and adverse events. Three-month follow-up included dental examinations.

RESULTS

Omadacycline achieved shorter TTD than continued macrolides (50.78 ± 20.71 vs. 72.46 ± 25.61 hours; P = 0.002) and higher 72-hour defervescence rate (55.6% vs. 26.1%; P = 0.026). On multivariate linear regression, continued macrolide therapy (B = 13.43 h, 95% CI: 2.02-24.84, P = 0.022), positive 23S rRNA mutation status (B = 20.85 h, 95% CI: 10.94-30.77, P<0.001), and systemic corticosteroid use (B = 21.21 h, 95% CI: 10.79-31.62, P<0.001) were independently associated with prolonged TTD. No significant difference was observed in radiological improvement (P = 0.668). Corticosteroid requirement was significantly lower in the omadacycline group than in the macrolide group (27.8% vs. 67.4%; P = 0.004). Adverse events were comparable (5.6% vs. 8.7%; P = 0.645). At 3-month follow-up, no clinically significant changes were observed in hematological indices, hepatic or renal function, or cardiac enzyme profiles, and dental examination revealed no discoloration or enamel hypoplasia in any patient.

CONCLUSION

In this retrospective cohort, omadacycline as second-line therapy was associated with significantly faster fever resolution than continued macrolide treatment, with acceptable short-term safety profiles over a 3-month follow-up. Prospective randomized trials are needed to confirm these findings.