Antibiotic Resistance and Plasmid-Mediated AmpC Beta-actamases among Clinical Isolates of Escherichia coli. Vali-e-Asr Hospital, Qom city, Iran, 2016

Plasmid mediated AmpC β-lactamase resistance in Escherichia coli is an emerging problem worldwide. Phenotypic methods are commonly used for detection of resistance production in Gram-negative isolates, but molecular data about the prevalence of plasmid-mediated AmpC-type resistance at the national level are needed. Hence, a prospective study was undertaken to determine of antibiotic resistance and detection of plasmid-mediated AmpC beta-lactamases among clinical isolates of Escherichia coli from Patients of Vali-e-Asr hospital in Qom city.

In this cross-sectional, descriptive study (conducted between 20 March and 20 May, 2016), 61 specimens of E. coli were collected from patients visiting Vali-e-asr Hospital in Qom, Iran, using conventional microbiological methods. To determine antibiotic resistance of the specimens, antibiogram obtained from disk diffusion test was used. Then, the screened strains were examined for PCR amplification of (CITM, FOX)-type plasmid-mediated AmpC beta-lactamases- producing genes. The results were analyzed by using SPSS software.

Among 61 E. coli specimens, 54 specimens (88.5%) were associated with urine and the rest (11.5%) with blood. In terms of gender, 49 patients (80.3%) were female and 12 patients (19.7%) were male. Among the specimens, the highest and least antibiotic resistance was observed against amoxicillin and imipenem, respectively. Resistance to ceftazidime was seen in 27 specimens (69.2%). From the results, CITM was identified in 7.4% of specimens, but FOX was not detected in specimens.

Results showed that the prescription of antibiotics for patients with plasmid-mediated AmpC beta-lactamases -producing strains not only did not stimulate recovery, but also led to the formation of resistant strains. In addition, the phenotypic methods do not produce the actual number of AmpC β-lactamase strains. Therefore, the conduction of genotypic studies in society leads to effective and faster treatment of patients, and prevents the spread of resistant bacterial isolates.