AUTHOR=Guo Lili , Xiao Tianan , Wu Liqin , Li Yan , Duan Xiaoxiao , Liu Wenhua , Liu Kaidi , Jin Wenjie , Ren Hao , Sun Jian , Liu Yahong , Liao Xiaoping , Zhao Yongda 

TITLE=Comprehensive profiling of serotypes, antimicrobial resistance and virulence of Salmonella isolates from food animals in China, 2015–2021

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1133241

DOI=10.3389/fmicb.2023.1133241

ISSN=1664-302X

ABSTRACT=<sec><title>Introduction</title><p><italic>Salmonella</italic> is a ubiquitous foodborne pathogen and mainly transmitted to human farm-to-fork chain through contaminated foods of animal origin.</p></sec><sec><title>Methods</title><p>In this study, we investigated the serotypes, antimicrobial resistance and virulence of <italic>Salmonella</italic> from China.</p></sec><sec><title>Results</title><p>A total of 617 <italic>Salmonella</italic> isolates were collected from 4 major food animal species across 23 provi nces in China from 2015-2021. Highest <italic>Salmonella</italic> prevalence were observed in Guangdong (44.4%) and Sandong (23.7%). Chickens (43.0%) was shown to be the major source of <italic>Salmonella</italic> contamination, followed by pigs (34.5%) and ducks (18.5%). The number of <italic>Salmonella</italic> increased significantly from 5.51% to 27.23% during 2015–2020. <italic>S</italic>. Derby (17.3%), <italic>S</italic>. Enteritidis (13.1%) and <italic>S</italic>. Typhimurium (11.4%) were the most common serotypes among 41 serotypes identifiedin this study. Antibiotic susceptibility testing showing that the majority of the <italic>Salmonella</italic> isolates were resistant to neomycin (99.7%), tetracycline (98.1%), ampicillin (97.4%), sulfadiazine/trimethoprim (97.1%), nalidixic acid (89.1%), doxycycline (83.1%), ceftria xone (70.3%), spectinomycin (67.7%), florfenicol (60.0%), cefotaxime (52.0%) and lomefloxacin (59.8%). The rates of resistance to multiple antibiotics in <italic>S</italic>. Derby and <italic>S</italic>.Typhimurium were higher than that in <italic>S</italic>. Enteritidis. However, the rate of resistance to fosfomycin were observed from higher to lower by <italic>S</italic>. Derby, <italic>S</italic>. Enteritidis, and <italic>S</italic>. Typhimurium. Biofilm formation ability analysis found that 88.49%of the Salmonella were able to produce biofilms, of which 236 Salmonella isolates were strong biofilm producer. Among the 26 types of antibiotics resistance genes (ARGs) were identified in this study, 4 ARGs (tetB,sul2,aadA2, and aph(3’)-IIa) were highly prevalent. In addition, 5 β-lactam resistance genes (<italic>bla</italic><sub>TEM</sub>, <italic>bla</italic><sub>SHV</sub>, <italic>bla</italic><sub>CMY-2</sub>, <italic>bla</italic><sub>CTX-M</sub>, and <italic>bla</italic><sub>OXA</sub>) and 7 quinolone resistance genes (<italic>oqxA</italic>, <italic>oqxB</italic>, <italic>qnrB</italic>, <italic>qnrC</italic>, <italic>qnrD</italic>, <italic>qnrS</italic>, and <italic>qeqA</italic>) were detected among these isolates. 12 out of 17 virulence genes selected in this study were commonly presented in the chromosomes of tested isolate, with a detection rate of over 80%, including <italic>misL</italic>, <italic>spiA</italic>, <italic>stn</italic>, <italic>pagC</italic>, <italic>iroN</italic>, <italic>fim</italic>, <italic>msgA</italic>, <italic>sopB</italic>, <italic>prgH</italic>, <italic>sitC</italic>, <italic>ttrC</italic>, <italic>spaN</italic>.</p></sec><sec><title>Discussion</title><p>This study provided a systematical updating on surveillance on prevalence of <italic>Salmonella</italic> from food animals in China, shedding the light on continued vigilance for <italic>Salmonella</italic> in food animals.</p></sec>