Emerging Challenges: High frequency of Antiseptic Resistance Encoding Genes and Reduced Biguanide Susceptibility in Antibiotic-Resistant Acinetobacter baumannii in Iran

Acinetobacter baumannii (A. baumannii) has been identified as a prevalent infectious agent that is frequently reported from patients in hospital intensive care units (ICUs). Annually, multi-drug-resistant (MDR) isolates pose a significant clinical challenge. The present study aimed to determine the prevalence of antiseptic resistance genes and the level of resistance to quaternary ammonium and biguanide compounds in A. baumannii isolates obtained from patients of north Khorasan province. All obtained A. baumannii isolates were examined for in The presence of genes that encode for resistance to antiseptics, including qacE, qacEΔ1, and blaOXA-23, was investigated. The broth microdilution method was utilized to determine the Minimum Inhibitory Concentrations (MICs) against antiseptic compounds. The study found that the majority of A. baumannii infections were observed in ICU patients (n=63, 84%). MDR and extensively drug-resistant (XDR) phenotypes were present in 53.2% and 46.7% of cases, respectively. Among 75 isolates, 48 (64%) had at least one resistance gene, including 24 (32%) isolates with only the qacE gene and 5 (6.7%) isolates with the qacEΔ1 gene. Furthermore, the coexistence of the qacE and qacEΔ1 genes was observed in nine (25.3%) isolates. Statistically significant differences were identified in the mean minimum inhibitory concentration (MIC) of chlorhexidine digluconate (CHG) between isolates with and without antiseptic resistance genes (81.4 µg/ml versus 27.9 µg/ml, P=0.001). The heightened minimum inhibitory concentration (MIC) levels exhibited by A. baumannii isolates against antiseptic agents constitute a significant medical concern. The presence of antiseptic-resistant genes and elevated MIC levels against antiseptic agents in MDR and XDR A. baumannii underscores the imperative for comprehensive monitoring of all A. baumannii isolates in hospital settings to ensure efficacious infection control measures.