First detection of mobilized colistin resistance mcr-۱ gene in Escherichia coli isolated from livestock and sewage in Iran

Background and Aim : The increasing prevalence of antibiotic resistance is one of the global health threats in the ۲۱st century.Polymyxins are the latest agents for the treatment of infections related to multidrug resistant gram negative bacteria (MDR-GNB) .plasmid-mediated colistin resistance genes have been reported in the Enterobacteriaceae family.Escherichia coli studies have particularly demonstrated that poultry and livestock can potentially carry isolates containing mcr genes;therefore, they can transfer drugresistant bacteria to humans.This study aimed to determine the prevalence of colistin-resistant isolates as well as the prevalence of mcr genes in E.coli in IranMethods : The ۶۵ isolates of E.coli were collected such as rectal stool swab samples from cows (n = ۳۸), chickens (n = ۴۷) and urban sewage samples (n = ۳۰) from two veterinary between February and August ۲۰۱۹ in Iran (Qazvin and Karaj). Colistin resistance was determined using the broth microdilution method by colistin Minimum inhibitory concentration (MICs) to characterize their antimicrobial susceptibility based on Clinical Laboratory Standards Institute guidelines۲۰۱۹,and PCR and ERIC-PCR were used to detect the mcr-۱,۶ genesResults : The antimicrobial susceptibility tests (MIC) showed that only ۳ (۴.۶%) isolates were resistant to colistin. All of the colistin-resistant isolates had MICs of ۴ μg/mL. According to the PCR results,only one(۳۳.۳%)colistin-resistant isolate from cows harboured the mcr۱ gene ,It was mcr-۱ positive. The nucleotide sequences of the mcr-۱ gene from E. coli were submitted to the GenBank database under accession number MN۵۳۹۱۰۵.Conclusion : In conclusion, to this study is first report the mcr-۱ gene in a colistin-resistant E. coli animal isolate in Iran. According to the present results, the spread of this gene in domestic animals and its possible transmission to humans raise public health concerns. To prevent the transmission of this gene to humans, it is necessary to the colistin-resistant strains. Proper administration of colistin and subsequently decreasing the selective pressure caused prevent the spread of antibiotic resistance

کلیدواژه ها:

Colistin resistance ، Escherichia coli ، livestock ، mcr-۱