Molecular detection of mobilized colistin resistance (&lt;i&gt;mcr-1&lt;/i&gt;) gene in &lt;i&gt;Escherichia coli&lt;/i&gt; isolates from Port Harcourt, Nigeria

K Otokunefor,A Amadi,E Tamunokuro

doi:10.4314/jasem.v23i3.5

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

Highlights

Colistin, a member of the polymyxin family of antibiotics has in recent years been described by the World Health Organization as a human medicine of critical importance (WHO 2011)
Though the initial report of this plasmid resistance noted a high association with animals, a SENTRY antimicrobial surveillance program published in 2016 which screened 390 clinical E. coli and Klebsiella pneumonia isolates previously noted as having MICs of ≥4μg/ml of colistin and 314 carbapenem resistant Enterobacteriaceae (CRE), found 19 positive for mcr-1
Following molecular confirmation, only 35 of the isolates were confirmed to be E. coli based on the presence of the E. coli specific 16s rRNA gene fragment, with a higher percentage of this comprised of the non-clinical isolates (Table 1)

Summary

Introduction

A member of the polymyxin family of antibiotics has in recent years been described by the World Health Organization as a human medicine of critical importance (WHO 2011). Though the initial report of this plasmid resistance noted a high association with animals, a SENTRY antimicrobial surveillance program published in 2016 which screened 390 clinical E. coli and Klebsiella pneumonia isolates previously noted as having MICs of ≥4μg/ml of colistin and 314 CRE, found 19 positive for mcr-1. A 2017 reported noted thatmcr-1 plasmid mediated colistin resistance has been detected in over 36 countries, three of which were African countries, with a single study from Nigeria (Al-Tawfiq et al, 2017, Olaitan et al, 2016).As this is a developing situation, surveillance is crucial to monitor the rate of development and dissemination of this resistance.

Results

Conclusion