Distribution of drug resistance genes and clinical characteristics of Acinetobacter baumannii isolated from the University Medical Center at Ho Chi Minh City

Abstract

Background: Infections resulting from A. baumannii in hospitals lead to numerous severe consequences as its antibiotic resistance, particularly to carbapenems, continues to rise. Given that resistance characteristics undergo constant changes due to mutations and gene transfer between species and strains, monitoring the real-time circulation of resistant strains is essential.

Methods: A descriptive cross-sectional method with analysis and experimentation were applied in this study. All strains of A. baumannii were isolated at the University Medical Center at Ho Chi Minh City from May 2020 to May 2021, then underwent antimicrobial susceptibility testing. Real-time PCR was performed to identify resistance genes, including blaOXA-51, blaOXA-23, blaOXA-48, blaOXA-58, and blaNDM-1. The patient’s information was collected by using the designated clinical research form.

Results: The study included 76 A. baumannii isolates. The resistance rates to imipenem and meropenem were 93.4%. Additionally, A. baumannii exhibited resistance to most of the other antibiotics investigated, with rates exceeding 80%. There was low resistance to Cefoperazone/sulbactam (6.1%) and colistin (5.3%). The distribution of resistance genes showed the prevalence of blaOXA-51 (100%), blaOXA-23 (88.2%), blaOXA-48 (43.4%), blaOXA-58 (2.6%), and blaNDM-1 (6.6%). The blaOXA-23 gene exhibited a statistically significant difference between carbapenem-susceptible A. baumannii (CSAB) and carbapenem-resistant A. baumannii (CRAB) (p < 0.001) and across different types of patient samples (p = 0.004). The distribution of the blaNDM-1 gene showed a statistically significant difference based on the clinical department sending the sample types (p = 0.029). There was a significant association between carbapenem resistance and the distribution of gene combinations (p < 0.001).

Conclusion: The carbapenem resistance rate was 93.4% for imipenem and meropenem, while it was low for cefoperazone/sulbactam (6.1%) and colistin (5.3%). blaOXA-51 holds significant importance in the identification of A. baumannii bacteria, and blaOXA-23 (88.4%) plays a decisive role in carbapenem resistance in A. baumannii at this hospital.