Characterization of Antimicrobial Resistance Pattern and Molecular Analysis among Extended Spectrum β-Lactamase-Producing Escherichia coli

Infection is a serious problem in medicine and appropriate antibiotic therapy is very important. Because of broad spectrum activity and low toxicity of β-lactam antibiotics, they are the most commonly used drugs. But, bacterial resistance to β-lactam antibiotics, has been considered as the global healthcare concern. The aim of study was to evaluate the antimicrobial resistance pattern and molecular characterization among ESBL-producing Escherichia coli isolated from patients with diarrhea admitted to a hospital in Ilam, Iran.
Totally, fifty E. coli isolates were investigated. Confirmatory tests for phenotypic detection of ESBLs were performed. Molecular identification of the blaTEM and blaSHV genes was carried out by PCR method. To identify genetic relatedness among isolates, Randomly Amplified Polymorphic DNA (RAPD) analysis was performed.
The antibiotic susceptibility results showed that the most effective antibiotic was imipenem and minimum effect was related to gentamicin. Thirty-one isolates (62%) were ESBL-producing organisms according to phenotypic method. The distribution of blaTEM and blaSHV genes among ESBL-producing isolates were 20 (64.5%) and 6 (19.3%), respectively. RAPD-PCR typing among isolates gave us eight different types. Twelve isolates were clustered in genotype A and all of them were ESBL-producer.
The present study showed noticeable incidence of ESBL-producing E. coli isolated from outpatients and hospitalized patients with diarrhea. Therefore, it seems that constant supervision is crucial to monitor the ESBL-producing microorganisms in hospitals and community.