Azithromycin resistance genes in clinically-isolated Escherichia coli and their relationship with those from wastewater

Abstract

Background

Due to the limited information on azithromycin-resistant E. coli and the difficulty in finding a reliable surveillance source for antibiotic resistance (AR) data, this study aimed to investigate the characteristics of such isolates in clinical samples and their correlation with wastewater isolates.

Methods

Samples were collected from a hospital in Iran over a six-month period and analysed for resistant E. coli, multiple antibiotic resistance (MAR), azithromycin resistance genes (AzRGs), phylogroups, and molecular types and compared with the corresponding parameters in wastewater isolates.

Significant findings

Isolates separated from the clinical setting were resistant to all antibiotics tested, from 5 % to 80 %, of which 95 % had MAR values > 0.2. The mph(A), erm(B), and ere (A) genes were prominent with a prevalence of 100 %, 69.2 % and 2.5 %, respectively, most of them in groups D (52.5 %) and A (42.5 %). The characteristics of the isolates showed a close correlation with those from municipal wastewater (P values for: Mean resistance prevalence = 0.71, MAR = 0.836, AzRGs = 0.134 and phylogenetic analysis = 0.39). This confirms that measuring AR levels in E. coli from wastewater environments may be representative of the corresponding levels in community.