The Occurrence of Plasmid Mediated Colistin Resistance Gene, mcr-1, in multi-drug Resistant Escherichia coli in fresh and Ready to eat vegetables in Lebanese Wholesale Markets

Abstract

Antimicrobial resistance is increasing worldwide. Colistin, also known as polymyxin E, is a last resort antibiotic that is used to treat complicated Gram-negative bacterial infections when other antibiotics fail. Colistin resistance has been considered to be chromosomally mediated, until the discovery of the mobile colistin resistance gene by Liu et al. in 2016. After that, the mobile colistin resistance gene, mcr-1, has been detected worldwide in more than 40 countries in different niches. Hence, the aim of this study is to determine the presence and dissemination of mcr-1 in Escherichia coli in fresh vegetables in different Lebanese wholesale markets. Results of this study show that colistin resistant E. coli were detected in 36.2% of the 105 vegetable samples collected from different wholesale markets and 24 mcr-1 positive E. coli were isolated. The minimum inhibitory concentration of colistin ranged between 4 and >64μg/ml. The majority (54.17%) of the isolates detected were multi-drug resistant, exhibiting resistance to penicillin (100%), ampicillin (58%), amoxicillin + clavulanic acid (96%), cefepime (4%), cefotaxime (25%), cephalexin (75%), cefixime (25%), doripenem (8%), meropenem (4%), imipenem (0%), gentamicin (0%), streptomycin (25%), tetracycline (33%), ciprofloxacin (4%), norfloxacin (8%), trimethoprim-sulfamethoxazole (29%), and chloramphenicol (17%). Various plasmid types have been detected in the isolates including IncI1α, IncF, IncI1γ, IncX1, IncFII, IncFIIS, IncW, IncA/C, and IncFIIK. BOX-PCR fingerprinting showed that the 24 mcr-1 positive E. coli isolates belonged to 18 different genotypes. This study is the first in Lebanon to detect the presence of mcr-1 in E. coli in fresh vegetables in wholesale markets. Our findings highlight an urgent need to devise immediate measures to control the proliferation of colistin resistance and mcr-1 in Lebanon.