Prevalence and Molecular Characteristics of Avian-Origin -1-Harboring in Shandong Province, China.

The objective of this study was to evaluate the prevalence and characteristics of avian-origin -1-harbouring in Shandong Province, China. During 2017-2018, a total of 668 non-duplicate 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 isolates by the agar dilution method; the mobile colistin resistance gene (-1) gene was screened by PCR, and -1 positive isolates were PCR-screened for antimicrobial resistance genes and typed by multi-locus sequence typing (MLST). Among the 668 , 102 (15.3%) harbored the -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 (102/102, 100%), followed by (90/102, 88.2%). Four PMQR genes were detected; (40/102, 39.2%) was the most commonly isolated PMQR gene, followed by (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, from poultry in Shandong could be a reservoir for the -1 gene, which could pose serious risks to human public health.