Genotyping and Molecular Analysis of Carbapenem-Resistant <i>Acinetobacter baumannii</i>: Correlations Between Antibiotic Resistance and Virulence Genes

Abstract

Background: Acinetobacter baumannii is frequently implicated in infections that originate within hospitals and other medical facilities worldwide, with high mortality rates driven by multidrug resistance and virulence. Objectives: The objective of this research is to investigate the patterns of antibiotic resistance, the presence of virulence-associated genes, and the genetic variability among clinical isolates of A. baumannii, focusing on carbapenem-resistant strains collected from healthcare settings in Tehran, Iran. Methods: We collected 40 samples of A. baumannii from different types of infections in the hospital. We tested how these bacteria respond to various antibiotics using standard lab methods. We also looked for specific genes that make the bacteria resistant to carbapenems and those that might help them cause infections. To understand how related these bacteria are to each other, we used a genetic fingerprinting technique called enterobacterial repetitive intergenic consensus (ERIC)-PCR. Results: Our results were concerning: 87.5% of isolates were resistant to multiple antibiotics. Each isolate had genes encoding carbapenemases, mainly blaOXA-51, blaOXA-24, and blaOXA-58. Additionally, 95% of isolates carried genes linked to their ability to cause disease, such as recA, ompA, and lipA. The genetic analysis showed that while some bacteria were closely related (suggesting spread within the hospital), others were more diverse, indicating multiple sources or ongoing evolution. Conclusions: This study sheds light on the worrying presence of highly resistant and potentially dangerous Acinetobacter isolates in Tehran’s hospitals. The mix of resistance and virulence genes, along with the genetic diversity, points to a need for stronger antibiotic stewardship, better infection control, and continuous monitoring to stop these bacteria from spreading and causing harm.