Acinetobacter baumannii: A comprehensive review of global epidemiology, clinical implications, host interactions, mechanisms of antimicrobial resistance and mitigation strategies.

Since the discovery of Acinetobacter baumannii, it has emerged as a significant global health threat due to its increasing prevalence in healthcare settings and remarkable ability to develop resistance to various antibiotics. This detailed review addresses global epidemiology, emphasizing the worldwide distribution of carbapenem-resistant A. baumannii (CRAb), which is particularly prevalent in high-density healthcare settings and regions with intensive antibiotic usage, such as India. Clinically, A. baumannii infection poses serious health challenges, with mortality rates ranging from 30 % to 75 % for multidrug-resistant (MDR) strains. The review highlights the clinical impact and disease spectrum of A. baumannii, associated with pneumonia, wound infections, bloodstream infections, and, urinary tract infections with a strong association to invasive medical procedures and devices. Additionally, it discusses human-pathogen interactions by exploring various mechanisms, persistence in hospital environments, and survival under harsh conditions. The review further elaborates on different resistance mechanisms, focusing broadly on antibiotic degradation, altered drug targets, reduced drug permeability, and efflux systems, which facilitate the survival and persistence of A. baumannii. Finally, it evaluates strategies to combat AMR, emphasizing infection control measures, antimicrobial stewardship, and the urgent need for innovative therapeutic approaches such as phage therapy and new antibiotic development. The review calls for concerted, collaborative efforts among researchers, healthcare professionals, and public health authorities to mitigate the global threat posed by MDR A. baumannii strains.