Minocycline-based Therapy for Carbapenem-resistant Acinetobacter baumannii Pneumonia: a Multicenter Retrospective Study.

Background: Minocycline is one of the few antibiotics that remain highly effective against carbapenem-resistant Acinetobacter baumannii (CRAB). However, the efficacy of minocycline for treating CRAB pneumonia has not been clearly demonstrated yet.

Methods: This multicenter retrospective cohort study evaluated adults treated for CRAB pneumonia at three tertiary care hospitals in South Korea from 2017 to 2022. Patients who received antibiotic regimens including minocycline were compared to those who received regimens not containing minocycline. The primary outcome measure was a 14-day clinical success. Multiple logistic regression with overlap weighting was conducted to compare the risk for outcome measures between the two groups.

Results: Among 411 patients (175 in the minocycline-included group and 236 in the minocycline-excluded group), the minocycline group had higher 14-day clinical success (57.1% vs. 34.3%, adjusted odds ratio [aOR]: 4.06, 95% confidence interval [CI]: 1.56-10.54, P=0.004) and lower 28-day mortality (aOR: 0.27, 95% CI: 0.09-0.79, P=0.016). The minocycline group was associated with longer mechanical ventilator-free days (aOR: 4.0 d, 95% CI: 2.1-6.0, P<0.001) without increase of nephrotoxicity or hepatotoxicity. Consistent results were observed in subgroup analyses for patients who stayed in the ICU, those who received colistin, and elderly patients.

Conclusion: Minocycline-based combination therapy demonstrated better outcomes than regimens without minocycline for CRAB pneumonia without increasing adverse events. Our study supports the role of minocycline in the treatment of CRAB pneumonia.