Prevalence of AmpC β-Lactamase and Regulatory Genes (LysR, QseB, and QseC) in Multidrug-Resistant Klebsiella pneumoniae Clinical Isolates from Al-Hillah, Iraq
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Abstract
Klebsiella pneumoniae is a critical opportunistic pathogen classified by the World Health Organization among priority drug-resistant organisms, owing to its capacity to acquire multidrug resistance (MDR) and express diverse virulence mechanisms. Understanding the molecular basis of resistance and the prevalence of regulatory genes in clinical isolates is essential for effective infection control. A total of 200 clinical samples (sputum and urine) were collected from hospitalized patients at two teaching hospitals in Al-Hillah, Iraq. Isolates were identified using the VITEK 2 Compact system, and antibiotic susceptibility testing was performed. Genomic DNA was extracted by the boiling method, and conventional PCR was used to detect five target genes: 16S rRNA, ampC, lysR, qseB, and qseC. Of 100 culture-positive samples, twenty (20%) were confirmed as K. pneumoniae with 99% probability. High resistance rates were recorded against cephalosporins (100%) and ceftazidime/ceftriaxone (90%), while amikacin showed the highest susceptibility (85%). The ampC gene was detected in 40% of isolates. All isolates (100%) carried 16S rRNA, lysR, and qseB genes, while qseC was present in 85%. The widespread resistance—even in isolates lacking the ampC gene—suggests the possible involvement of additional concurrent mechanisms, such as ESBLs, efflux pumps, and porin loss, although these were not directly tested in the present study. The universal prevalence of regulatory genes lysR and qseB underscores their role in bacterial adaptation and virulence. Combined molecular and phenotypic approaches are essential for comprehensive characterization of MDR K. pneumoniae in clinical settings.
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