Molecular profiling and computational mutational analysis of bla-NDM-1 in clinical Acinetobacter baumannii isolates

Acinetobacter baumannii is the major cause of healthcare-associated infections attributed to its remarkable ability to resist multiple antibiotics. The study aimed to characterize the clinical A. baumannii isolates, evaluate their antibiotic resistance patterns, determine the prevalence of bla-NDM-1 gene, and perform in-silico mutational analysis to evaluate the structural and functional impact of its variant.

Isolates were cultured on blood and MacConkey agars, identified at biochemical (API 20NE) and molecular levels, and assessed their antibiotic susceptibility using the Kirby-Bauer and MIC assays. PCR and sequencing analyses were performed to detect the variant of bla-NDM. A model of the wild-type bla-NDM-1 structure was created by AlphaFold, while the mutant P28A was generated and refined in PyMOL and validated by SAVES, GOR IV, and stability prediction tools.

Resistance among isolates was seen to multiple antibiotics used in this study, such as carbapenem, aminoglycoside, fluoroquinolone, and penicillin, while sensitivity was retained to colistin, polymyxin B, and tigecycline. Based on the antibiotic resistance profiles, 25.3% and 69.3% of the isolates were categorized as multi-drug resistant (MDR) and extensively drug-resistant (XDR), respectively, with 82.7% of isolates showing MAR index > 0.2. Mutation in a bla-NDM gene was observed only in 8% (n = 6) of the isolates belonging to A. baumannii and found to possess C→G substitution (P28A). In-silico study showed slight differences in the structure, decreased stability, and greater flexibility, indicating that the mutation is likely neutral and adaptive.

The threat posed by MDR A. baumannii strains is significant; hence, their detection, infection control, and genetic screening are critical for preventing further transmission, limiting severe complications, and minimizing patient mortality rates.