Exploring the Antibiotic Resistance Profile and blaOXA-23 Sequence Analysis in Acinetobacter Baumannii Isolates from a Tertiary Care Hospital, Lahore, Pakistan

Abstract

Background: Acinetobacter baumannii is a major cause of healthcare associated infections, particularly in intensive care units, and exhibits extensive resistance to multiple antibiotic classes including carbapenems. Objective: To determine the antibiotic resistance profile, biofilm formation, and prevalence of the blaOXA-23 gene among A. baumannii isolates from a tertiary care hospital in Lahore, Pakistan. Methods: A total of 150 clinical specimens (pus, sputum, and blood) were collected from the surgical ICU over a three month period. Isolates were identified using API-20E, polymerase chain reaction (PCR), and Sanger sequencing. Antimicrobial susceptibility testing was performed by the Kirby-Bauer disk diffusion method in accordance with CLSI (2023) standards. Biofilm formation was quantified using the microtiter plate assay. Detection and sequence analysis of blaOXA-23 were conducted through PCR amplification and phylogenetic comparison with regional strains. Results: Out of 150 samples, 50 (33.3%) yielded A. baumannii. Twenty isolates (40%) demonstrated biofilm formation, and 19/20 (95%) of these carried blaOXA-23. Overall, blaOXA-23 was present in 19/50 (38%) isolates. Complete resistance (100%) was observed to meropenem and cephradine, while imipenem and amikacin resistance reached 75%. One XDR isolate harboring blaOXA-23 showed 96–98% genetic similarity with regional sequences. Conclusion: The high frequency of blaOXA-23 among biofilm-forming A. baumannii isolates underscores an alarming trend in carbapenem resistance and necessitates stringent infection control practices and antibiotic stewardship in tertiary care settings.

Keywords: Acinetobacter baumannii, Antimicrobial Susceptibility, blaOXA-23, Biofilm, Carbapenem Resistance.