Identification of plasmid encoded qepA efflux pump gene in Citrobacter freundii isolates from a renowned hospital, Bangladesh.

Background and Objectives: The emergence of plasmid-mediated resistance to quinolones is a growing global threat that complicates the control of multidrug-resistance (MDR) in Enterobacteriaceae. This study was conducted to determine the frequency of the qepA gene and its association with antibiotic resistance in Citrobacter freundii isolates from various clinical samples. Materials and Methods: To conduct this study, a total of 27 C. freundii isolates collected from urine, endotracheal aspirates, sputum, blood, and stool samples were identified using standard biochemical tests and culture methods. Their susceptibility to ciprofloxacin was determined via the MIC agar dilution method. Specific primers were used to confirm C. freundii and detect the qepA gene by PCR. Subsequently, DNA sequencing was performed using a capillary method, and the sequences were compared to similar genes available in GenBank. Results: Among the isolated C. freundii strains, 77.78% were resistant to ciprofloxacin. Of these resistant isolates, 9.52% were found to harbor the qepA gene. Sequencing and BLAST analysis confirmed a 99% similarity to the Citrobacter koseri strain CD4359 plasmid pCD4359 (GenBank accession number KR259132.1) and revealed a point mutation at position 58. Conclusion: This finding highlights the distribution of the qepA gene in clinical isolates, emphasizing the need for continuous molecular surveillance to screen PMQR determinants and to implement effective antimicrobial stewardship strategies.