Phenotypic and Genotypic Detection of AmpC Enzymes(MOX and CIT) in Clinical Isolates of Escherichia coli

Background and Objectives: AmpC β-lactamase enzymes cause multi-drug resistance. The diagnosis of these enzymes in clinical isolates of bacteria is important in epidemiological, research studies and hospital infections control because plasmid genes can be transmitted to other organisms in the hospitals. The purpose of this study is the detection of AmpC enzymes (MOX and CIT) in the isolated strains of E. coli in three educational hospitals in Hamadan (Iran). Materials and Methods: 102 strains of E. coli were isolated from the three hospitals in Hamadan from March to September 2017. The isolated gram negative bacteria were identified using common biochemical tests. Antibiotic sensitivity of isolated strains was studied by standard disk diffusion method and based on CLSI protocol .To detect phenotypic AmpC activity, the AmpC detection disks were used. The clinical isolates with MIC ³ 8 μg/ml for cefoxitin were included for evaluation by AmpC diagnosis disks. To detect genes encoding for AmpC, PCR method was used. Results: Sixty eight isolates (66.6%) were resistant to third generation cephalosporin of which 61 (59.8%) isolates had MIC ³ 8 μg/mL to cefoxitin. All 68 isolates were analyzed by AmpC detection disks, of which 10(14.7%) were AmpC- β-lactamase producers. By PCR method, 24 (35.2%) isolates had cit, 46(67.6%) for mox genes.Conclusion: High resistance to cephalosporins has been observed among the clinical isolates. Due to the possibility of plasmid transferring of ampC genes between bacterial, changing consumption patterns of antibiotics and the treatment protocol is necessary. The results of this study suggest that physicians should pay attention while prescribing antibiotic and send the sample to laboratory for the antibiogram tests so that the best medical choice is given to the patients. The emergence of plasmid-mediated AmpC and ESBL β-lactamase producing E. coli and possible risk of the spread of antibiotic resistance in the clinical situations demand timely and careful treatment.