What is the optimal antibiotic treatment strategy for carbapenem-resistant Acinetobacter baumannii (CRAB)? A multicentre study in Korea

Abstract

Objectives: The optimal treatment option for carbapenem-resistant Acinetobacter baumannii (CRAB) is still limited. This study investigated the efficacy of three or more antibiotic types and regimens for treatment of CRAB infection in high CRAB endemic areas.

Methods: A multicentre retrospective study was conducted to evaluate the efficacy of treatment types and regimens of CRAB infections in 10 tertiary hospitals in the Republic of Korea. The outcomes comprised 7-day and 28-day mortality, and clinical and microbiological responses at 7 days, 28 days, and the end of treatment. Nephrotoxicity and hepatotoxicity were evaluated as drug adverse reactions.

Results: A total of 282 patients were included in the study. Among the CRAB strains, the two most susceptible antibiotics were colistin (99.6%) and minocycline (80.4%). A combination of colistin and carbapenem significantly reduced 7-day mortality, and a sulbactam-containing regimen significantly reduced 28-day mortality. Colistin monotherapy was significantly associated with increased 7-day and 28-day mortality. A minocycline-containing regimen showed the best microbiological responses at 7 days, 28 days, and the end of treatment. Colistin and tigecycline were associated with increased nephrotoxicity and hepatotoxicity, respectively. Subgroup analysis of patients with pneumonia showed similar results to the overall CRAB infection.

Conclusions: A combination of colistin and carbapenem and sulbactam-containing regimen may contribute improved mortality in CRAB infections. Colistin monotherapy should be considered cautiously in severe CRAB infections or CRAB pneumonia. A minocycline-containing regimen showed the best microbiological responses, and further studies may be needed to evaluate improved mortality.

Keywords: Acinetobacter baumannii; Acinetobacter infections; Antibacterial agents; Combination drug therapy; Drug resistance.