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Molecular Detection of Colistin Resistance Gene (MCR-1) in E. coli Isolated from Cloacal Swabs of Broilers
Muhammad Zulqarnain, Noreen Sarwar*, Aftab Ahmad Anjum, Sehrish Firyal1, Tahir Yaqub and Masood Rabbani

Institute of Microbiology; 1Institute of Biochemistry and Biotechnology, University of Veterinary and Animal Sciences, Lahore, Pakistan
*Corresponding author:


The current emergence of antimicrobial resistance against colistin is a major challenge to treat multi drug resistant Gram negative bacteria. Broiler chickens can function as a source for dissemination of antimicrobial resistant strains to humans. In present study, 150 cloacal swabs of broiler birds, collected from retail shops in Lahore, were processed for isolation of E.coli. E. coli isolates (n=100) were tested for antimicrobial sensitivity to colistin sulfate using broth dilution method. The resistant isolates were tested by polymerase chain reaction for mcr-1 and mcr-2 genes of colistin resistance. The isolates, found resistant by broth dilution method, were also checked for pathogenicity by adding congo-red dye in nutrient agar. Phenotypically colistin resistant isolates were also tested for other antibiotics e.g. Amoxicilline (30ug), Cefepime (30ug), Gentamycin (10ug), Chloramphenicol (30mcg), Clindamycin (2ug), Ciprofloxacine (5ug), Norfloxacin (10ug), Amikacin (30ug), Lincomycin (10ug) and Streptomycin (10ug) by disc diffusion method. Out of 100 isolates, 59 showed resistance to colistin while taking MIC as 4mg/L. The colistin resistant E.coli also showed multidrug resistance against other antibiotics tested. Among 59 phenotypically colistin resistant isolates, only 7 isolates were possessing mcr-1 gene but none of the strains was observed bearing mcr-2 gene. About 15% (5/59) colistin resistant isolates were pathogenic by congo red dye test. The results indicated presence of mcr-1 harboring E. coli in commercial birds that can contribute in spread of mcr-1 gene.

To Cite This Article: Zulqarnain M, Sarwar N, Anjum AA, Firyal S, Yaqub T and Rabbani M, xxxx. Molecular detection of colistin resistance gene (MCR-1) in E. coli isolated from cloacal swabs of broilers. Pak Vet J.


ISSN 0253-8318 (Print)
ISSN 2074-7764 (Online)