Staphylococcal food poisoning caused by Staphylococcus argenteus harboring staphylococcal enterotoxin genes

• Published in: International journal of food microbiology Vol. 265; pp. 23 - 29
• Main Authors: Wakabayashi, Yuki, Umeda, Kaoru, Yonogi, Shinya, Nakamura, Hiromi, Yamamoto, Kaori, Kumeda, Yuko, Kawatsu, Kentaro
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 16.01.2018; Elsevier BV
• Subjects: Agglutination; Coagulase; Coagulase - genetics; Cooking; Disease Outbreaks; DNA Primers; Electrophoresis, Gel, Pulsed-Field; Enterotoxin; Enterotoxins - genetics; Food contamination; Food contamination & poisoning; Food handling; Food poisoning; Gel electrophoresis; Gene sequencing; Genes; Genetic analysis; Genomes; Handlers; Humans; Japan; Kitchen utensils; Mobile genetic elements; Multilocus Sequence Typing; Outbreaks; Pathogenicity; Pathogens; Poisoning; Polymerase Chain Reaction - methods; Pulsed-field gel electrophoresis; Staphylococcal enterotoxin G; Staphylococcal Food Poisoning - diagnosis; Staphylococcal Food Poisoning - microbiology; Staphylococcus - classification; Staphylococcus - genetics; Staphylococcus - isolation & purification; Staphylococcus - pathogenicity; Staphylococcus argenteus; Staphylococcus infections; Toxins; Utensils; Osaka Japan; Enterotoxin; Staphylococcus argenteus; Food poisoning; Mobile genetic elements
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2017.10.022

Staphylococcal food poisoning (SFP) is caused by staphylococcal enterotoxins (SEs) preformed in food materials. SE genes are encoded on mobile genetic elements and are widely found across Staphylococcus species including S. argenteus, although most SFP cases are caused by S. aureus. S. argenteus, recently discriminated from S. aureus as a novel species, are non-pigmented staphylococci phenotypically related to S. aureus. In 2014 and 2015, two independent food poisoning cases occurred in Osaka, Japan, in which non-pigmented staphylococci were predominantly isolated. Several enterotoxin genes (seb, seg, sei, sem, sen, seo, and selu2) were found in their genome and the production of SEB was confirmed by reverse passive agglutination tests. The non-pigmented isolates from patients, food handlers, food, and cooking utensils all produced the same pulsed-field gel electrophoresis pattern. These non-pigmented isolates were coagulase-positive and biochemically identical to S. aureus. We performed further genetic analysis using nucA sequencing and multi-locus sequence typing, and identified these isolates as S. argenteus. We also found that seb was encoded on the Staphylococcus aureus pathogenicity island, while seg, sei, sem, sen, seo, and selu2 were encoded on the enterotoxin gene cluster. From these results, we concluded that the two food poisoning outbreaks were SFP cases caused by S. argenteus harboring SE genes. •Staphylococcus argenteus were predominantly isolated in food poisoning cases.•The isolates harbored several enterotoxin genes on mobile genetic elements.•Horizontal transfer of enterotoxin genes from S. aureus was implied.