First detection of mobilized colistin resistance gene in isolated from livestock and sewage in Iran.

Currently, few studies have investigated the mechanisms of resistance to colistin in Iran. The aim of this study was to investigate -harbouring dissemination in livestock and sewage in Iran. A total of 115 samples from cows ( = 38), chickens ( = 47) and urban sewage samples ( = 30) were collected. The presence of genes including and β-lactamase ( , , , , , ) for colistin-resistant isolates was investigated by multiplex PCR method. Genetic association of colistin-resistant strains was also evaluated by ERIC PCR. Sixty-five isolates were identified as . Meaningless were resistant to colistin. The highest (26.1%) and lowest (3.07%) resistance were shown to ampicillin and meropenem respectively. Among the three colistin-resistant isolates, 2 (66%) were multidrug resistant, with one of them being positive and the other one positive for DHA β-lactamase gene. No genes were found. Minimum inhibitory concentration of -producing isolate was 4 mg/L by microbroth dilution. This study reports, first the detection of in from farm animals in Iran, a finding that is indicative of a global distribution of this plasmidic element and threatning the use of colistin as a last resort antibiotic. No clonal relationship was observed between the colistin-resistant isolates by ERIC-PCR. Monitoring the presence of these strains in animal sources help as to controlling the spread of resistance genes from animal to human is vital.