Significance of the Detection of Staphylococcal Enterotoxin A Gene in Low Fat Milk Which Caused a Serious Outbreak of Food Poisoning

Abstract

In June 2000, there was a large-scale outbreak of food poisoning after consumption of Snow Brand low fat milk. In the evening of a day the incident made public, some cartons of low fat milk were brought to our laboratory for examination. Next day, we detected only staphylococcal enterotoxin (SE) A gene among SE (AῐE) genes by PCR in left-over milk samples or samples from the same lots that patients had consumed. We presumed that the outbreak was caused by the intake of SEA. We subsequently confirmed the presence of SEA in these samples. To investigate the existence of SE (AῐE) genes in milk, we examined 100 samples of commercial low fat milk and milk by PCR, but none of the genes was detected. We estimated the detection limit of SEA gene in low fat milk by PCR. Four strains of SEA-producing Staphylococcus aureus cultures were serially diluted in low fat milk. The SEA gene was detected at levels of 5.5 10 2 to 1.610 4 cfu/mL of S. aureus. These amounts of S. aureus are higher than the values in raw milk reported previously. Therefore we consider that SE genes in low fat milk should usually be undetectable by our PCR. This study shows that quick detection of SE genes by PCR is very helpful to analyze outbreaks, especially if no significant bacterium can be cultured.

Short communication: Pasteurization as a means of inactivating staphylococcal enterotoxins A, B, and C in milk

“…Intoxication by Staph. aureus is most frequently identified as the cause of human outbreaks resulting from raw milk consumption or products made thereof (Yamashita et al, 2003;Barker and Gomez-Tome, 2013;Claeys et al, 2013;Janstova et al, 2014). By contrast, with commercially processed milk, consumer health is potentially at risk from Staph.…”

Prevalence and characterization of Staphylococcus aureus isolated from goat milk powder processing plants

“…However, milk powder is easily contaminated with S. aureus (Wang et al, 2012). Although pasteurization can kill S. aureus cells, enterotoxins produced by S. aureus can still cause foodborne diseases in humans (Yamashita et al, 2003). In addition, studies have reported that some S. aureus strains persist in powdered infant formula (Wang et al, 2012).…”

Bacteriological and molecular studies on staphylococcus aureus isolated from raw milk

“…These results disagreed with Shin et al, (2002) recorded that most Staph. aureus strains produced enterotoxin B and D.Also Yamashita et al, (2003) detected only Staphylococcal enterotoxin sea gene among se (a-e) genes by PCR in milk samples. Also Lim et al, (2004) detected SEA in 32 isolates, SEB in 3 isolates, SEC in 1 isolate and SEA in 1 isolates.…”