Resistance Mechanisms Of Acinetobacter Baumannii In North Indian Clinical Isolates: A Molecular Study Of Β-Lactam, Carbapenem, Cephalosporin, Fluoroquinolone, And Aminoglycoside Genes

Background- The WHO recently added to priority list Carbapenem-resistant Acinetobacter baumannii (CRAB) major infection cause death throughout the developing world. With time the bacteria have become smarter so antimicrobial resistance is major problem so treatment of infection. Aim- This study explored the relationship between antimicrobial resistance patterns and identified the resistance genes responsible for β-lactam, fluoroquinolone, and aminoglycosides. A. baumannii isolates susceptibility patterns of antimicrobial agent and conventional PCR was used to detection of β-lactamase leading gene to carbapenem- resistant class ( blaSHV, blaTEM, blaVEB, blaPER, blaGES, blaKPC, blaCTX-M-1), (MBL) genes (blaIMP, blaVIM, blaNDM-1), Oxacillinase genes (blaOXA-48, blaOXA-23, blaOXA-24/40, blaOXA-58), Aminoglycoside-modifying enzyme (AME) genes (aac(3)-Ia, aac(3)-IIa, aph(3)-Ia, ant(2)-Ia), Plasmid-mediated quinolone resistance genes (qnrA, qnrB, qnrS), and DNA gyrase genes (parC, gyrA). Results- Resistance genes were detected in 62.09% of blaOXA-23, 15.3% of blaPER, 24.18% of blaNDM, 15.6% of blaSHV-1, 36.6% of parC, 20.26% of aph (3')-VIa, 23.5% of ant(1a), and 9.1% of aac(1a), predominantly in extensively drug-resistant (XDR-AB) isolates. Additionally, 2.6% of blaOXA-58-like genes were found in multidrug-resistant (MDR-AB) isolates. A high prevalence of blaOXA-23-like and specific ESBL genes in extensively drug-resistant (XDR) strains suggests the co-evolution of resistance mechanisms, contributing to enhanced resistance profiles. The co-occurrence of carbapenem resistance genes with aminoglycoside-modifying enzymes or ESBL genes shows A. baumannii versatility and flexibility to acquire several resistance mechanisms; co-resistance is more common in XDR isolates. The high prevalence of blaOXA-23, blaNDM, and parC among resistant isolates means that carbapenem and fluoroquinolone resistance has a major part in the continuing existence of A. baumannii outbreaks.