Molecular Detection and Characterization of Antimicrobial Resistance Genes among Multidrug-Resistant Gram-Negative Bacteria Isolated from Clinical Specimens

Abstract

Background: Multidrug-resistant (MDR) Gram-negative bacteria are a major clinical concern due to limited therapeutic options. Aim: To determine antimicrobial resistance patterns and characterize selected ESBL and carbapenemase genes among MDR Gram-negative bacteria isolated from clinical specimens. Methods: Eighty clinical specimens from 80 participants (40 males and 40 females) were examined. Sixty-eight Gram-negative isolates were recovered, of which 46 MDR isolates underwent PCR detection of blaCTX-M, blaTEM, blaSHV, blaNDM, blaKPC, blaVIM, blaIMP, and blaOXA-48-like. Results: Of 68 isolates, 46 (67.6%) were MDR. E. coli was predominant (36.8%), followed by K. pneumoniae (25.0%). blaCTX-M (54.3%) was the most frequent resistance gene, followed by blaTEM (41.3%), blaSHV (30.4%), blaNDM (21.7%), and blaOXA-48-like (17.4%). Multiple resistance genes occurred in 45.7% of MDR isolates.  Discussion: The high MDR rate and predominance of blaCTX-M, together with clinically important carbapenemase genes, indicate substantial molecular diversity of resistance and emphasize the importance of molecular surveillance. Conclusion: MDR Gram-negative bacteria showed frequent ESBL and carbapenemase gene carriage. Combining phenotypic susceptibility testing with molecular detection may improve AMR surveillance and infection-control strategies