Distribution of blaKPC, blaNDM, and blaOXA-48-like Genes among Carbapenem-Resistant Clinical Klebsiella pneumoniae Isolates Using Real-Time PCR

الملخص

Carbapenem-resistant Klebsiella pneumoniae is an important cause of difficult-to-treat hospital infections. Resistance is frequently mediated by carbapenemase genes, particularly blaKPC, blaNDM, and blaOXA-48-like. Real-time PCR detection of these genes can support infection-control decisions and guide antimicrobial stewardship. This study determined the distribution of blaKPC, blaNDM, and blaOXA-48-like among carbapenem-resistant clinical K. pneumoniae isolates and evaluated their association with specimen source, hospital ward, and antimicrobial resistance profile. A cross-sectional clinical microbiology study was performed on 124 non-duplicate carbapenem-resistant K. pneumoniae isolates recovered from routine human clinical specimens. Isolates were identified by culture, biochemical testing, and automated identification. Antimicrobial susceptibility testing was performed using an automated system and disk diffusion, with interpretation according to current clinical breakpoints. Genomic DNA was extracted from pure colonies. Short-amplicon TaqMan real-time PCR assays were used to detect blaKPC, blaNDM, and blaOXA-48-like. At least one carbapenemase gene was detected in 112/124 isolates (90.3%). blaNDM was the most frequent gene, detected in 68 isolates (54.8%), followed by blaOXA-48-like in 54 isolates (43.5%) and blaKPC in 18 isolates (14.5%). Dual-gene carriage was detected in 31 isolates (25.0%), mainly blaNDM + blaOXA-48-like. Triple-gene carriage was detected in 5 isolates (4.0%). Gene-positive isolates showed significantly higher multidrug resistance than gene-negative carbapenem-resistant isolates. Short-amplicon real-time PCR provided a rapid and image-free method for detecting clinically important carbapenemase genes in K. pneumoniae. The predominance of blaNDM and blaOXA-48-like suggested a local resistance pattern requiring continuous surveillance.