ObjectiveCarbapenem-resistant Acinetobacter baumannii (CRAB) is a common cause of ventilator-associated pneumonia (VAP). Some in vitro data favour various combination antibiotic therapy. However, there is a need for more in vivo studies for the management of VAP caused by CRAB. This retrospective study was done to evaluate the effectiveness of various combination antibiotic therapy including sulbactam on outcomes of VAP caused by CRAB. MethodsAdult patients (age ≥18 years) diagnosed with VAP caused by CRAB were included. Patients with polymicrobial infections were excluded from the study. Patients with CRAB associated VAP who were given sulbactam based antibiotic combinations were observed for outcomes. The primary outcome was 28-day mortality after diagnosis of VAP caused by CRAB. Reduction in serum HsCRP (High sensitivity C-reactive protein) during treatment and requirement of inotropes were the secondary outcomes. Outcomes were compared between various sulbactam based antibiotic combination therapies. ResultsA total of 103 patients were included. A total of 44 (42.7 %) patients received sulbactam and minocycline or sulbactam and polymyxin B dual antibiotic combination, and 59 (57.3 %) patients received sulbactam, polymyxin B and minocycline triple antibiotic combination. The percentage difference in 28 days mortality was 27.51 % (95 % CI 8.03 %–44.06 %; p = 0.005) in dual vs triple sulbactam based antibiotic combination therapy. The percentage difference in requirement of inotropes during therapy and HsCRP reduction after 7 days of therapy was 23.65 % (95 % CI 6.43 %–38.3 %; p = 0.007) and 25.1 % (95%CI 10.1 %–38.2 %; p < 0.001) respectively when compared between dual vs triple sulbactam based antibiotic combination therapy. ConclusionTreatment with sulbactam, polymyxin B and minocycline combination antibiotic therapy was associated with significantly lower 28-day mortality. Moreover, the lower requirement of inotropes during treatment and a significant reduction in HsCRP level favours this combination antibiotic therapy in VAP caused by CRAB.