Antimicrobial Resistance of Clinical Klebsiella pneumoniae Isolates: Involvement of AcrAB and OqxAB Efflux Pumps

Abstract

Background: Over the last several decades, the AcrAB and OqxAB efflux pumps have been found to cause multidrug resistance (MDR) in various bacteria, most notably Klebsiella pneumoniae. Antibiotic resistance surges with increased expression of the acrAB and oqxAB efflux pumps. Methods: In accordance with CLSI guidelines, a disk diffusion test was carried out using 50 K. pneumoniae isolates obtained from various clinical samples. CT was computed in treated samples and compared to a susceptible ciprofloxacin strain (A111). The final finding is presented as the fold change in the target gene's expression in treated samples relative to a control sample (A111), normalized to a reference gene. As CT=0 and 20 equals one, relative gene expression for reference samples is often set to 1. Results: The highest rates of resistance were recognized with cefotaxime (100%), cefuroxime (100%), cefepime (100%), levofloxacin (98%), trimethoprim-sulfamethoxazole (80%), and gentamicin (72%), whereas imipenem (34%) had the lowest rates. Overexpression of acrA and acrB, oqxA and oqxB, regulators marA, soxS, and rarA were greater in ciprofloxacin-resistant isolates compared to the reference strain (strain A111). There was also a moderate connection between ciprofloxacin MIC and acrAB gene expression and a moderate connection between ciprofloxacin MIC and oqxAB gene expression. Conclusion: This work provides a deeper knowledge of the role of efflux pump genes, particularly acrAB and oqxAB, as well as transcriptional regulators marA, soxS, and rarA, in bacterial resistance to ciprofloxacin.