Determination of <i>MCR-1</i> Gene and Antibiotic-Resistant <i>Escherichia coli</i> Isolates from Clinical and Non-clinical Samples

Abstract

Background: In recent years, resistant infections and antibiotic resistance in livestock have been increasing, and it seems that these issues will cause more problems in the future. Objectives: This study investigates the association between the pattern of Escherichia coli antibiotic resistance (ECAR) and the identification of the mobilized colistin resistance (mcr-1 gene) among clinical and non-clinical samples. Methods: In this study, 265 samples were collected from clinical (human urine, N = 79) and non-clinical sources (animal feces from poultry and livestock farms, N = 186). All samples were processed, and E. coli bacteria were isolated and identified. The agar dilution method was used to evaluate colistin resistance, and the presence of the mcr-1 gene was characterized among E. coli isolates. Results: Out of 265 samples (clinical and fecal), 37.97% (30/79) of clinical samples and 37.63% (70/186) of animal feces showed growth of E. coli. The highest number of E. coli isolates was found in feces from livestock farms (71.48%; 50/70). Antimicrobial susceptibility testing (AST) of E. coli isolated from clinical samples showed that the highest resistance (46.66%) was to ciprofloxacin, and the lowest resistance (16.66%) was to colistin. Analysis of polymerase chain reaction (PCR) data also showed that 60% of colistin-resistant isolates from clinical urine samples and 70% from animal feces samples were positive for the plasmid-mediated mcr-1 gene. Conclusions: The findings indicate that the high frequency of the mcr-1 gene among both clinical and animal-collected isolates may be a significant factor in the development of colistin resistance among circulating E. coli isolates.