Determination of colistin resistance in Escherichia coli isolates from foods in Turkey, 2011-2015

Antimicrobial resistance of pathogenic microorganisms is an emerging public health concern. Intensive use of antibiotics in food animals might increase antimicrobial resistance in foodborne pathogens. Colistin is a last resort antibiotic for treatment of multidrug resistant (MDR) Gram negative pathogens. The recent antimicrobial resistance studies revealed a mobile antimicrobial resistance gene (mcr) that provides resistance to colistin. Furthermore, the gene has been found in different genera. Therefore, the aim of this study was to determine colistin resistance of Escherichia coli isolates (N=48) isolated in between 2011 and 2015 from food samples in Turkey. In addition, 5 mcr genes and their variants were screened by performing PCR on resistant isolates. 4 E. coli isolates were found resistant to colistin above the epidemiological cut-off value (Minimum inhibitory concentration (MIC) > 2mg/L). None of the resistant isolates had the mcr genes. Further studies with human and food isolates should be conducted to figure out which gene or genes are responsible for colistin resistance.