title: Incidence of Staphylococcus aureus and associated risk factors in Nham, a Thai fermented pork product.
abstract: Staphylococcus aureus is one of the most prevalent bacterial pathogens causing food-borne disease worldwide. Staphylococcal food poisoning is caused by ingestion of staphylococcal enterotoxins (SEs) pre-formed in the implicated food. In this study, the incidences of S. aureus and classical SEs (SEA-SEE) contamination in 'Nham', a traditional Thai fermented pork product, were determined. Among 155 Nham samples tested, as high as 39.35% of the samples were positive for S. aureus (2-3500 MPN/g), but none were positive for the SEs. The risk factors for S. aureus contamination were highly correlated with the manufacturer and the pH of the product. A predictive model determined the probability of the presence of S. aureus to be < or = 0.24 at the pH < or = 4.6. During the fermentation process, the number of S. aureus slightly increased in the first day and decreased afterward. S. aureus counts continued to decrease when Nham was stored refrigerated. The negative result for enterotoxins and low counts of S. aureus in Nham surveyed in this study, and reduction of the pathogen counts during fermentation and storage suggested that there is very low risk of staphylococcal food poisoning from consuming properly fermented Nham.
authors.affiliation: Food Biotechnology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), 113 Thailand Science Park, Phahonyothin Road, Pathumthani 12120, Thailand.
authors.forename: Nipa
authors.initials: N
authors.lastname: Chokesajjawatee
authors.forename: Sarinya
authors.initials: S
authors.lastname: Pornaem
authors.forename: Young-Gun
authors.initials: YG
authors.lastname: Zo
authors.forename: Sanit
authors.initials: S
authors.lastname: Kamdee
authors.forename: Plearnpis
authors.initials: P
authors.lastname: Luxananil
authors.forename: Srianant
authors.initials: S
authors.lastname: Wanasen
authors.forename: Ruud
authors.initials: R
authors.lastname: Valyasevi
mesh_terms: D000818:Animals; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004768:Enterotoxins; D005285:Fermentation; D005506:Food Contamination / Q000032:analysis* / Q000517:prevention & control; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008461:Meat Products / Q000382:microbiology*; D011237:Predictive Value of Tests; D012307:Risk Factors; D013202:Staphylococcal Food Poisoning / Q000453:epidemiology / Q000517:prevention & control; D013211:Staphylococcus aureus / Q000254:growth & development*; D013552:Swine; D013785:Thailand
chemical_list: D004768:Enterotoxins