Phenotypic and Genotypic Resistance Patterns to Anti-microbial Biocides in <i>Escherichia coli</i> Isolates in Ardabil, Iran 2021 - 2023

Abstract

Background: Escherichia coli is one of the most prevalent gram-negative bacteria that cause various infections, such as septicemia, pneumonia, gastrointestinal, and urinary tract infections (UTIs). Escherichia coli resistant to antimicrobial biocides is an important problem worldwide. Objectives: This study aimed to evaluate the resistance patterns of E. coli to some biocides. Methods: Two hundred E. coli isolates from outpatients with UTIs were identified by phenotypic standard methods. To determine the minimum inhibitory concentration (MIC) of biocides (benzalkonium chloride, chlorhexidine gluconate, triclosan, and formaldehyde), a microdilution method was used. PCR assays were conducted to detect five efflux pump-encoding genes, including emrE, mdfA, qacE, qacG, and qacED1. Results: The highest resistance among tested biocides was observed with formaldehyde and benzalkonium chloride, with a sixty-four μg/mL MIC90 level. Chlorhexidine digluconate and triclosan were more effective biocides against E. coli, with 16 and 4 μg/mL MIC90, respectively. The prevalence of efflux pump-encoding genes mdfA, emrE, qacED1, qacG, and qacE was 88.5%, 80%, 24.5%, 6%, and 4%, respectively. Conclusions: This study indicates that the resistance rate to biocides is high. The efflux pump-encoding genes may cause resistance to biocides.