Molecular detection of mobilized colistin resistance (mcr-1) gene in Escherichia coli isolates from Port Harcourt, Nigeria

Abstract

The emergence of plasmid borne colistin resistance in recent years has been problematic as a result of the potential for rapid dissemination through bacterial populations. This mcr-1 mediated resistance has been reported from around the globe and active surveillance is essential to monitor the developing issue. This study set out to determine the occurrence of such strains in a group of 60 Escherichia coli isolates using DNA extraction and amplification techniques. Following molecular confirmation of the identities of the E. coli isolates based on the detection of E. coli specific 16sRNA gene fragments, phenotypic colistin resistance of isolates was determined and isolates were screened for the mcr-1 gene using standard procedures. Of the 35 confirmed E. coli isolates, 60% were found to be colistin resistant, with a higher level of resistance noted among the non-clinical isolates. Plasmid mediated mcr-1 resistance was however found to be present in only 8.6% of total isolates, making up 14.3% of the colistin resistant strains. This mcr-1 mediated resistance was only noted in clinical isolates however. This detection of mcr-1 mediated colistin resistance in E. coli isolates from Port Harcourt, Nigeria is worrisome as it could point at a looming epidemic of colistin resistance and hence the development of untreatable bacterial isolates. Further studies are essential to properly assess the scope and spread of this situation.

Keywords: Colistin resistance, mcr-1, Escherichia coli, Nigeria