Assessment of colistin-resistant Escherichia coli isolates from Chicken in Qazvin

Introduction and Objectives: Colistin is considered as the last-resort of treatment for multi-drug-resistant gram-negative bacteria infections (MDR-GNB) in both human and animals. In recent studies, the presence of plasmid-mediated colistin resistance genes has been detected in various countries. In this study, we examined the presence of these genes in Escherichia coli isolates from chiken. Materials and Methods: The 60 isolates of Escherichia coli were collected from chicken fecal samples in Qazvin, between 2017 and 2019. Colistin resistance was determined using the broth microdilution method by colistin Minimum inhibitory concentration (MICs) to characterize their antimicrobial susceptibility based on Clinical Laboratory Standards Institute guidelines 2019, and PCR was used to detect the plasmid-mediated mcr-1,and mcr-2 genes. Results: Among 60 isolates, 7 (11.6 %) were resistant to colistin with MIC ≥ 4 ??/??. No isolates were detected to harbor mcr-1, mcr-2 genes. Conclusion: There was no relationship between resistance to colistin and presence of mcr genes. It seems that other mechanisms are involved in colistin-resistant isolates and further studies are need to find out the colistin resistance mechanisms in our isolates.

کلیدواژه ها:

Escherichia coli ، Colistin ، plasmid-mediated mcr