Characterization of an Unusual Foodborne Illness Including an Outbreak and Sporadic Illness Caused by Three Bacterial Pathogens Via a Takeaway Service.

Takeaway food services are an emerging business in China and have a potential impact on food safety. An unusual foodborne illness associated with takeaway food delivered through a logistics company on August 27, 2018 is reported. Epidemiological investigations showed that 28 patients from 2 companies were diagnosed with gastroenteritis symptoms. The major symptoms included nausea (24, 85.71%), vomiting (24, 85.71%), diarrhea (22, 78.57%), and abdominal pain (22, 78.75%). Laboratory investigations showed that six Staphylococcus aureus isolates, three Salmonella enteria serovar livingstone isolates, and one Vibrio parahaemolyticus isolate were detected. Six S. aureus isolates were detected from one patient, food, and a food handler, and all six S. aureus isolates had the same pulsed-field gel electrophoresis (PFGE) pattern and multilocus sequence typing (MLST) genotype. Staphylococcal enterotoxin A was detected from food and the six S. aureus isolates. These results confirmed that S. aureus isolates were the major agent causing this foodborne illness. Three Salmonella isolates with the same PFGE pattern and MLST genotype were detected from patients. This was the first time that Salmonella isolates have been identified as causing a foodborne disease outbreak in China. Only one O4:K8 serotype of V. parahaemolyticus with the tdh gene isolate was detected from one patient. These results confirmed that this was an unusual foodborne illness that included an outbreak associated with two different pathogens and a third pathogen sporadic illness. Takeaway services pose a risk to public health because they have the potential to distribute contaminated products over a large geographic area within a short time. Therefore, more attention should be paid to prevent and control foodborne illnesses caused by contaminated food from takeaway services.

Serotype, virulence, and genetic traits of foodborne and clinical Vibrio parahaemolyticus isolates in Shanghai, China.

Vibrio parahaemolyticus is a major foodborne pathogen in China and other countries. In this study, a total of 578 clinical V. parahaemolyticus strains and 51 foodborne strains were isolated during the period from 2009 to 2011 in the eastern coastal city of Shanghai, China. Their serotypes, virulence genes, pandemic traits, and genotyping were investigated. A total of nine O groups and 20 K types were identified by serological analysis of all isolates. Six different O groups and 14 different K types were detected among the 578 clinical strains. Eight different O groups and five K types were detected among the 51 foodborne strains. The O3:K6 serotype was the dominant serotype. A total of 200 representative clinical strains and 51 foodborne isolates were analyzed for virulence genes, pandemic traits, and genotyping. Of the clinical strains, 92.5% had the virulence genes tdh and/or trh. Four foodborne isolates had virulence genes; one trh-positive strain was O3:K6 and three tdh-positive strains were either O4:KUT or O3:KUT. Molecular typing by pulsed-field gel electrophoresis also showed divergence among the nonpandemic strains, although the pandemic strains formed a cluster. These results suggest high serodiversity and genetic diversity of V. parahaemolyticus. Pathogenic isolates were present in food, thus representing a public health risk and warranting epidemiological and ecological monitoring to ensure safety.