Antibiotic Resistance and Phenotypic and Genotypic Detection of AmpC Beta-Lactamases among Klebsiella pneumoniae Isolates from Kermanshah Medical Centers

Acquisition of AmpC β-lactamase enzymes is one of the important factors in the resistance of Klebsiella pneumoniae to β-lactam antibiotics. The purpose of this study was to determine the antibiotic resistance, phenotypic frequency of AmpC, and detection of MOX, CIT, DHA, ACC, EBC, and FOX genes in K. pneumoniae strains isolated from medical centers in Kermanshah. In this descriptive cross-sectional study, 100 suspected cases of K. pneumoniae, were collected from 2013 to 2015 from patients referring to three hospitals and one laboratory in Kermanshah city. antimicrobial susceptibility disk diffusion test and AmpC phenotypic screening test, were performed using boronic acid combination method, and after extraction of bacterial genome, AmpC genes were identified by multiplex PCR method. Resistance to third generation cephalosporins, was 70%, and resistance to aztreonam was reported 65%. The highest and the lowest resistance was to ampicillin (98.5%) and carbapenems (less than 10%), respectively; 27.1% of the isolates phenotypically produced AmpC and a high percentage of isolates from the infectious ward and intensive care unit (ICU) was AmpC producer. The frequency of MOX, CIT, FOX, and DHA genes was obtained to be 11.4%, 10%, 2.8%, and 1.4%, respectively. However, EBC and ACC genes, were not found in any of the isolates. The results of this study showed that phenotypic tests alone are not sufficiently accurate in the evaluation of AmpC enzymes. Therefore, simultaneous use of genotypic methods is necessary. In this study, the high prevalence of AmpC genes, especially MOX and CIT in K. pneumoniae isolated from infectious and ICU wards in Kermanshah hospitals is indicative of importance of dissemination of this group of β-lactamase enzymes.