Prevalence and Antimicrobial Resistance Profile of Acinetobacter baumannii Among ICU Isolates in a Tertiary Care Centre in Central India

Abstract

Background: Acinetobacter baumannii is an important non-fermenting Gram-negative bacillus causing healthcare-associated infections, especially in intensive care units (ICUs). Phenotypic identification may not reliably differentiate A. baumannii from other members of the Acinetobacter calcoaceticus-baumannii complex. This study aimed to determine the prevalence, antimicrobial susceptibility pattern, and genotypic confirmation of A. baumannii among ICU isolates from a tertiary care centre in central India. Methods: This observational cross-sectional laboratory-based study was conducted in the Department of Microbiology, Index Medical College Hospital & Research Centre, Indore, from January 2024 to December 2025. A total of 266 ICU clinical samples were included. Isolates were identified phenotypically by standard microbiological methods, and antimicrobial susceptibility testing was performed by the Kirby-Bauer disk diffusion method and broth microdilution methods according to CLSI guidelines. PCR was performed for detection of the intrinsic blaOXA-51-like gene for confirmation of species. Results: Among 266 ICU samples, 41(15.41%) were phenotypically identified as Acinetobacter species, and all 41(100%) were confirmed as A. baumannii by blaOXA-51-like gene detection. Most isolates were recovered from patients aged 30-60 years, 23(56.1%) and from male patients 27(65.9%). The Medical ICU contributed the highest number of isolates, 16 (39.0%), and endotracheal aspirate was the predominant specimen source, 28(68.3%). High resistance was observed to cephalosporins, fluoroquinolones, aminoglycosides, beta-lactam/beta-lactamase inhibitor combinations, and carbapenems. The overall prevalence of A. baumannii among ICU specimens was 15.4% (41/266; 95% confidence interval [CI]: XX–XX%). Based on antimicrobial susceptibility profiles, XX isolates fulfilled the criteria for multidrug-resistant (MDR) A. baumannii according to the international definitions proposed by Magiorakos et al. Conclusion: A. baumannii is an important ICU-associated multidrug-resistant pathogen in Central India. Molecular confirmation by blaOXA-51-like gene detection improves species-level identification. The high carbapenem resistance rate emphasises the need for antimicrobial resistance surveillance, infection control, ventilator care bundles, and antimicrobial stewardship in ICU settings. Categories: Other, Trauma, Infectious Disease

Keywords: Acinetobacter baumanii, antimicrobial susceptibility, blaoxa-51-like gene, carbapenem resistance, central india, icu, non-fermenting gram-negative bacilli