Plasmid-mediated AmpC β-Lactamase gene analysis in Klebsiella Pneumoniae clinical isolates

Abstract

Background: In Gram-negative bacteria, including Klebsiella pneumoniae, the production of AmpC beta-lactamase enzymes is one of the main resistance mechanisms for beta-lactam antibiotics. This study aimed to investigate the phenotypic and molecular characteristics of AmpC beta-lactamases in K. pneumoniae clinical isolates in Southwest Iran. Methods: This study was conducted on 55 K. pneumoniae strains collected from various clinical samples. Identification of isolates was done using routine bacteriological and biochemical tests. After performing the antibiotic sensitivity test, the cefoxitin-resistant strains were analyzed using the phenotypic test in terms of the production of AmpC beta-lactamase enzymes. Finally, the frequency of plasmid-mediated AmpC genes was determined using a polymerase chain reaction test. Results: Out of the 55 isolates, 63.6% (n = 35) were obtained from urine, 9.1% (n = 5) from blood, 12.7% (n = 7) from wounds, and 14.6% (n = 8) from sputum. The highest resistance rate was observed against amoxicillin (98.2%), followed by cefotaxime (78.2%) and ceftriaxone (72.7%). According to the phenotypic tests, the prevalence of AmpC producers was 25.4%. Of all isolates, 36.3% (20/55) harbored different AmpC-associated genes, and blaMOX, blaCIT, blaEBC, and blaDHA genes were detected in 1, 2, 8, and 13 strains, respectively. None of the isolates harbored blaACC and blaFOX genes. Conclusion: It is important to revise the prescription policy of effective antibiotics in this region, since a significant prevalence of AmpC beta-lactamase-producing isolates has made antibiotic resistance a serious concern.

Keywords

• ampc beta-lactamase
• antibiotic resistance
• klebsiella pneumoniae