spa typing and enterotoxin gene profile of Staphylococcus aureus isolated from bovine raw milk in Korea

Staphylococcus aureus is a major etiological pathogen of bovine mastitis, which triggers significant economic losses in dairy herds worldwide. In this study, S. aureus strains isolated from the milk of cows suffering from mastitis in Korea were investigated by spa typing and staphylococcal enterotoxin (SE) gene profiling. Forty-four S. aureus strains were isolated from 26 farms in five provinces. All isolates grouped into five clusters and two singletons based on 14 spa types. Cluster 1 and 2 isolates comprised 38.6% and 36.4% of total isolates, respectively, which were distributed in more than four provinces. SE and SE-like toxin genes were detected in 34 (77.3%) isolates and the most frequently detected SE gene profile was seg, sei, selm, seln, and selo genes (16 isolates, 36.3%), which was comparable to one of the genomic islands, Type I nuSabeta. This is a first report of spa types and the prevalence of the recently described SE and SE-like toxin genes among S. aureus isolates from bovine raw milk in Korea. Two predominant spa groups were distributed widely and recently described SE and SE-like toxin genes were detected frequently.

Staphylococcus aureus and food poisoning

Food-borne diseases are of major concern worldwide. To date, around 250 different food-borne diseases have been described, and bacteria are the causative agents of two thirds of food-borne disease outbreaks. Among the predominant bacteria involved in these diseases, Staphylococcus aureus is a leading cause of gastroenteritis resulting from the consumption of contaminated food. Staphylococcal food poisoning is due to the absorption of staphylococcal enterotoxins preformed in the food. Here, we briefly review the latest data on staphylococcal enterotoxins and some papers exemplifying the interactions between S. aureus and the food matrix; environmental factors affecting staphylococcal enterotoxin production are discussed

Isolation and characterization of Salmonella enterica Weltevreden cytotoxin.

Cytotoxin of Salmonella enterica subspecies enterica serovar Weltevreden (BM-1643), isolated from buffalo meat, was purified and characterized physicochemically and immunologically. Cell-free culture supernatant (CFCS) of the organism showing marked cytotoxicity to Vero cells and least enterotoxicity to rabbit ligated ileal loop (RLIL) model, was salt precipitated with ammonium sulphate (60% saturation level) and dialysed. Precipitated dialysed preparation (60% PDP) when filtered through Sephadex G-100 column yielded two peaks, of which second peak (SG-100 SP) contained the cytotoxic activity. Upon filtration of SG-100 SP through SG-200 column, three peaks were obtained. Second peak (SG-200 SP), which was cytotoxic, yielded a single protein band of approximately 60-70 kDa in polyacrylamide gel electrophoresis and 3 protein bands of lower, molecular weight (13.5-56 kDa) in SDS-PAGE analysis. Cytotoxic preparation was maximally active at pH 7 to 8. On heating above 60 degrees C, cytotoxicity decreased gradually with insignificant activity left after treatment at 121 degrees C (15 min). Cytotoxin was inactivated by treatment with trypsin and protease but not by papain or lipase enzymes. It was immunogenic in rabbit and antiserum neutralized the cytotoxicity of cytotoxic preparations of homologous as well as heterologous Salmonella serovars.