AUTHOR=Zhao Xiaonan , Ju Zijing , Wang Guisheng , Yang Jie , Wang Fangkun , Tang Hui , Zhao Xiaomin , Sun Shuhong 

TITLE=Prevalence and Antimicrobial Resistance of Salmonella Isolated From Dead-in-Shell Chicken Embryos in Shandong, China

JOURNAL=Frontiers in Veterinary Science

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2021.581946

DOI=10.3389/fvets.2021.581946

ISSN=2297-1769

ABSTRACT=<p>The present study was designed to explore the <italic>Salmonella</italic> prevalence and antimicrobial resistance characteristics in the context of chick mortality at hatching in China. Between December 2015 and August 2017, 1,288 dead-in-shell chicken embryos were collected from four breeder chicken hatcheries in Tai'an, Rizhao, Jining, and Heze, China. <italic>Salmonella</italic> isolates were successfully recovered from 6.7% of these embryos (86/1,288) and were evaluated for serotype, antimicrobial susceptibility, Class 1 integron prevalence, antimicrobial resistance gene expression, and multilocus sequence typing (MLST). <italic>Salmonella</italic> Thompson (37.2%), and <italic>Salmonella</italic> Infantis (32.6%) were the two most prevalent isolates in these chicken embryos, and 66.3% of isolates exhibited robust ampicillin resistance, while 55.8% of isolates exhibited multi-drug resistance (MDR). The majority of isolates harbored the <italic>bla</italic><sub>TEM</sub> gene (74.4%), with the <italic>qnrS</italic> gene also being highly prevalent (50.0%). In contrast, just 27.9% of these isolates carried Class 1 integrons. These 86 isolates were separated into four sequence types (STs), whereby ST26 (32.2%) was the most prevalent. Overall, these results suggested that <italic>Salmonella</italic> infections may be an important cause of chicken embryo mortality in China, and that efforts to support the appropriate use of antibiotics in managing poultry populations are essential.</p>