Prevalence of Plasmid-Mediated AmpC ß-Lactamase Genes in Clinical Isolates of Klebsiella Pneumoniae in Arak City, Iran

ß-lactamase enzymes are the most important factor for antimicrobial resistance in Gram-negative rods. This study aimed to determine the antimicrobial susceptibility pattern and the occurrence of AmpC ß-lactamase genes in clinical isolates of Klebsiella pneumoniae (K. pneumonia). A total of 100 K. pneumonia isolates was collected from clinical specimens obtained in the Vali-Asr hospital، Arak، Iran. The isolates were identified on the basis of standard biochemical tests. Antimicrobial susceptibility pattern was defined by the standard disk diffusion method according to CLSI (Clinical and Laboratory Standards Institute) guidelines. Plasmid-mediated AmpC β-lactamases genes were detected by using polymerase chain reaction (PCR) method. Of the 100 isolates tested، 19 (19%) were demonstrated to harbor AmpC β-lactamases by multiplex PCR; eight isolates carried β-lactamases genes of the CIT group، seven isolates carried genes belonging to the MOX group، three and one isolates carried genes belonging to the EBC and DHA groups، respectively. ACC and FOX groups were not found in our isolates. This study is the first report of MOX group of AmpC β-lactamases in K. pneumoniae in Iran. High prevalence of plasmid-mediated AmpC in the central hospital of Arak، indicating the antibiotic resistant، is a major concern; hence، antibiotic prescription policy should be revised and infection control measure is necessary to be improved.