Investigation of Efflux Pump and Quorum Sensing Genes in Acinetobacter baumannii Isolates

Objective: Acinetobacter baumannii can cause serious hospital infections, particularly in intensive care units (ICUs) and in immunocompromised patients. Prolonged ICU stay, antibiotic use, mechanical ventilation, intravenous catheters, urinary catheters, endotracheal tubes, tracheostomy, and a high density of infected or colonized patients in the unit are the main risk factors. Acinetobacter baumannii strains are clinically important due to their ability to develop high levels of resistance to antibiotics and to survive for long periods in hospital environments. This study aimed to investigate the efflux pump and quorum sensing genes in A. baumannii strains isolated from blood cultures sent to our laboratory. Methods: Fifty-three multidrug-resistant A. baumannii strains isolated from blood cultures submitted to our hospital’s Medical Microbiology Laboratory were included. Species identification and minimum inhibitory concentration (MIC) values were determined using the VITEK 2 automated system (bioMérieux, France). Efflux pump genes (adeABC) and quorum sensing genes (luxI, luxR) were investigated by polymerase chain reaction (PCR). After PCR, all samples were evaluated by agarose gel electrophoresis to detect specific DNA bands. Results: In this study, the bap gene was the least frequently detected gene (1.9%), while the efflux pump gene adeA was found in all isolates (100%). The other efflux pump genes were detected at the following rates: adeB 96.2%, adeC 45.3%, adeI 86.8%, adeJ 67.9%, adeK 98.1%, and adeR 98.1%. Among the quorum sensing genes, luxI was detected in 41.5% and luxR in 47.2% of the isolates. High levels of resistance were observed against carbapenems and quinolones, while no resistance was detected against colistin. Conclusion: This study contributes to a better understanding of the epidemiology and pathogenesis of A. baumannii infections. Similar studies will help identify the genes involved in resistance mechanisms of multidrug-resistant A. baumannii strains and support the development of new treatment strategies and policies. Furthermore, identifying resistance factors in hospital-based studies will help select the most effective treatment methods and contribute posi-tively to both patient health and the national economy.