Abstract
The objective of this study was to evaluate the prevalence and characteristics of avian-origin mcr-1-harbouring Escherichia coli in Shandong Province, China. During 2017—2018, a total of 668 non-duplicate E. coli isolates were separately collected from 8eight large intensive poultry farms in Shandong Province. Antimicrobial susceptibility testing for 10 antimicrobial agents commonly used in farms was performed on all E. coli isolates by the agar dilution method; the mobile colistin resistance gene (mcr-1) gene was screened by PCR, and mcr-1 positive isolates were PCR-screened for antimicrobial resistance genes and typed by multi-locus sequence typing (MLST). Among the 668 E. coli, 102 (15.3%) harbored the mcr-1 gene; high antimicrobial resistance rates were observed for ampicillin (100/102, 98.0%), followed by amoxicillin (99/102, 97.1%) and florfenicol (97/102, 95.1%), and a low level of resistance was found for amoxicillin/clavulanic acid (24/102, 23.5%). Five ESBL genes were detected, and all isolates carried blaTEM (102/102, 100%), followed by blaCTX–M (90/102, 88.2%). Four PMQR genes were detected; aac(6)-Ib-cr (40/102, 39.2%) was the most commonly isolated PMQR gene, followed by qnrA (10/102, 9.8%). Thirty-eight different kinds of STs were identified, and the dominant ST was ST93 (19/102, 18.6%), followed by ST48 (9/102, 8.8%). In summary, E. coli from poultry in Shandong could be a reservoir for the mcr-1 gene, which could pose serious risks to human public health.
Highlights
Antimicrobial resistance is an ongoing severe public and animal health problem (Poirel et al, 2011)
Mcr-1 positive plasmids could coexist with other resistance genes, notably ESBL genes; this has probably led to the emergence of pan-drug resistant strains and treatment failure (Haenni et al, 2016)
The 102 mcr-1 positive isolates originated from poultry of farm 1 (n = 4), farm 2 (n = 5), farm 3 (n = 42), farm 4 (n = 1), farm 5 (n = 1), farm 6 (n = 42), farm 7 (n = 6), and farm 8 (n = 1)
Summary
Antimicrobial resistance is an ongoing severe public and animal health problem (Poirel et al, 2011). This issue occurs in pathogenic bacteria and in non-pathogenic bacteria. Polymyxin use in animals and humans has promoted the selection and spread of mcr-1 drug-resistant strains (Sun et al, 2018). Since mcr was discovered in food, animal and human isolates from Southern China, it has already spread to over 40 countries, implying that it played a prevalent role in the transferability of polymyxin resistance (Teo et al, 2017; Liu et al, 2016). Mcr-1 positive plasmids could coexist with other resistance genes, notably ESBL genes; this has probably led to the emergence of pan-drug resistant strains and treatment failure (Haenni et al, 2016)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
