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Infections due to aquatic products that are contaminated with Salmonella spp. are great risks to public health, however, epidemiological information and risk factors regarding these Salmonella contamianted food are limited in China. The study aimed to examine the incidence of Salmonella spp. in fresh aquatic products in China, and the MLST patterns and antimicrobial-resistance profiles of the Salmonella isolates identified. Out of the 300 aquatic food samples purchased from retail markets in 15 provincial Chinese capitals during 2015.6–2016.6, sixteen (5.3%) were found to be positive for Salmonella spp. and fifteen distinct serovars were detected. Clinically-important serovars predominated the isolates recovered, with almost all other identified serovars also implicated in human diseases. Antimicrobial susceptibility analysis of the 18 non-repetitive isolates showed that 14 isolates (77.8%) present drug resistance and seven isolates (38.9%) showed multidrug resistance phenotypes. High frequencies of resistance to streptomycin (66.7%), ampicillin (38.9%), and tetracycline (33.3%) were observed. Of particular concern, 22.2% of isolates were resistant to ciprofloxacin. The incidence of Salmonella serovars in the retail aquatic products and their high antimicrobial-resistance frequencies could constitute potential risks to public health. This study is valuable for supporting risk assessment, epidemiological investigation, and disease prevention. • Aquatic products in this study were found highly contaminated with Salmonella spp.. • Clinically-important serovars predominated the isolates recovered in this study. • All of the identified serovars have previously been implicated in human diseases. • The Salmonella isolates recovered showed high antimicrobial-resistance frequencies. • These antimicrobial-resistant Salmonella spp. are potential risks to human health. [ABSTRACT FROM AUTHOR]

Salmonella is a leading cause of foodborne disease worldwide and ready-to-eat (RTE) foods are regarded as a major source of infection and outbreak. In recent years, the consumption of Chinese RTE foods has raised markedly with the pace of life increasing. However, the prevalence of Salmonella in these foods in China and its potential risk to public health has not been well determined and evaluated. This study was undertaken to investigate the prevalence of Salmonella in Chinese retail RTE food products and to determine serotype distribution, antimicrobial resistance, virulence, and genetic diversity of recovered Salmonella isolates. Out of the 539 RTE food products collected and tested from July 2011 to May 2014, 19 (3.5%) were positive for Salmonella . The contamination levels of Salmonella were mostly in the range of 0.3–10 most probable number (MPN)/g, with one sample exceeding 110 MPN/g. Among the 50 isolates identified, 37 isolates (74.0%) were resistant to at least one antimicrobial, while 21 isolates (42.0%) were resistant to more than three antimicrobials. High rates of resistance were observed for tetracycline (56.0%), ampicillin (38.0%), and streptomycin (34.0%). PCR analysis of 15 virulence genes showed that the avrA , ssaQ , mgtC , siiD , sopB , and bcfC genes were detected in all 50 isolates, whereas the genes located on plasmid and prophage varied significantly among the isolates. Ten distinct serovars were identified and S . Derby, S. Meleagridis, S . Enteritidis, and S. Senftenberg were the most prevalent serovars. A total of 11 sequence types by multilocus sequence typing and 20 profiles by pulsed-field gel electrophoresis were generated for the 20 selected isolates and the combination of these two methods presented a better knowledge of genetic diversity of Salmonella isolates. The study provided a systematical surveillance on prevalence of Salmonella in Chinese RTE foods and indicates its potential risk to public health. [ABSTRACT FROM AUTHOR]