Molecular Detection of AmpC Beta-Lactamase Genes Involved in Antibiotic Resistance of Klebsiella pneumoniae Strains Isolated from Intensive Care Unit Patients of Pasteur Hospital in Bam City, Iran

Background: Klebsiella pneumoniae is a well-known opportunistic pathogen that can cause a variety of human infections and has the ability to form biofilm. Furthermore, this microorganism has AmpC beta-lactamases, which are associated with extensively antimicrobial resistance. Aim: The aim of this study was to investigate the molecular detection of AmpC beta-lactamase genes involved in antibiotic resistance of K. pneumoniae strains isolated from intensive care unit patients of Pasteur Hospital in Bam City, Iran. Materials and Methods: In this cross-sectional study, 120 K. pneumoniae isolates were collected from different clinical samples between January 2023 and June 2023. Antibiotic susceptibility of these isolates was determined by the disc diffusion method according to Clinical and Laboratory Standards Institute guidelines. The detection of AmpC β-lactamases was then evaluated by phenotypic and molecular methods. Biofilm formation capacity was also measured using a standard protocol. Results: The results of this study showed that 80% of the isolates were multidrug resistance (MDR). In addition, 100 isolates had the ability to form biofilm. After primary AmpC screening, 71 isolates were selected for phenotypic detection of AmpC β-lactamases, of which 36 of them were AmpC producers by CCDT test, while the molecular results showed that a total of 111 isolates (92.5%) carried at least one AmpC-associated gene. The frequencies of blaDHA, blaCIT, blaFOX, blaMOX, and blaACT genes were 50% ( n = 60), 42.5% ( n = 51), 39.17% ( n = 47), 30% ( n = 36), and 14.17% ( n = 17), respectively. Conclusions: The results of this research exhibited a high prevalence of MDR isolates. In addition, the majority of isolates formed biofilm and were molecularly identified as AmpC producers, suggesting the need for continued monitoring and investigation to improve our understanding of the epidemiology and evolution of AmpC beta-lactamases in K. pneumoniae .