Plasmid mediated mcr-1 gene is a predominant colistin resistance gene among clinical samples of Escherichia coli rather than hospital samples

The emergence of plasmid-mediated colistin-resistant bacterial strains in recent years has caused significant alarm in the field clinical medicine therapy, particularly with the increasing incidence of carbapenem resistant Enterobacteriaceae globally. Colistin, the last resort antibiotic, has been increasingly used to treat multidrug resistant-bacterial infections among human and in animal care leading to mutations and resistance among sensitive strains. The study aims to investigate the prevalence of mcr (1-5) genes associated with colistin resistance in human samples in Karbala city in Iraq. Three hundred clinical samples were collected from patients including human samples (200 urine samples and 100 burn swab samples) and 50 hospital environment swabs collected. Samples were cultured on selective media for isolating Escherichia coli (E. coli) and identified using VITEK2 compact system. One hundred sample revealed the growth of E. coli. Isolates showed different traits of antibiotic resistance including multidrug resistant 50% and extensive drug resistant 21% and pan resistant E coli which recorded 5%. The prevalence of colistin resistance among E. coli isolates was 6%. The mcr1 gene was the only gene detected among the 6 isolates, 3 were isolated from urine samples and 3 were isolated from burn samples. In Conclusion, mcr1 gene is a predominant gene among community acquired isolates of E. coli in contrast to the hospital environment. Results recommend re-evaluation for the source of resistance strains and especial concern should be directed toward horizontal transmission through animals and food markets to humans because of the wide usage of colistin in veterinary medications.