Plasmid-Mediated Colistin Resistance Gene mcr-1 in an Escherichia coli ST10 Bloodstream Isolate in the Sultanate of Oman

Address correspondence to: Agnes Sonnevend, MD, PhD, Department of Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, United Arab Emirates, E-mail: [email protected]

Introduction

Since its first description in November 2015, plasmid-mediated colistin resistance encoded by the mcr-1 gene¹ has been identified in various species of Enterobacteriaceae in five continents.² Lately, it has also been reported from multiple countries of the Arabian Peninsula.^3,4 However, although clinical isolates were tested previously,³ it has not been identified in the Sultanate of Oman yet.

Methods

During a two-year period between July 2014 and June 2016, 22 nonrepeat Enterobacteriaceae clinical isolates (21 Klebsiella pneumoniae and one Escherichia coli) were identified as colistin resistant by Phoenix BD (Beckton, Dickinson and Company, New Jersey) and E-test (BioMérieux, Marcy-l'Etoile, France) in a tertiary care hospital in Muscat, the capital of the Sultanate of Oman. The isolates were stored at -80°C. To identify plasmid-mediated colistin resistance, their genomic DNA was subjected to PCR for the mcr-1 and mcr-2 genes as described.^1,5

The isolate identified as mcr-1 positive was subjected to multilocus sequence typing.⁶ The presence of virulence factors (cdt, hlyA, papC, papA, papEF, fimH, PAI, fyuA, bmaE, sfa/foc DE, iutA, traT, focG, cvaC, gafD, sfaS, cnf1, afa/dra, nfaE, rfc, ibe A, iha, upaH, upaB, Kps MTII, K5, K1, Kps MTIII, sat, ireA, iroN, usp) and resistance genes (bla