Articles
PREVALENCE OF ENTEROTOXIN-PRODUCING STAPHYLOCOCCUS AUREUS IN SUSHI
Article number
973_16
Pages
131 – 134
Language
English
Abstract
Presence of Staphylococcus aureus and its ability to produce enterotoxin in sushi purchased from supermarkets and local markets were studied.
The results revealed that the aerobic plate count and Staphylococcus sp. found in sushi from supermarkets were 3 log CFU/g and 2 log CFU/g less than in sushi from local markets, respectively.
Fifty-one colonies typical of Staphylococcus sp. on Baird Parker agar were examined for morphological and biochemical characteristics, and only two were identified as coagulase-positive S. aureus (M031 and S022). S. aureus M031 and S022 were investigated for enterotoxin production in TSB incubated at 35°C for 24 h, and enterotoxin was analyzed by ELISA (TECRA SET VIA). Only S. aureus M031 incubated for 24 h was able to produce enterotoxin when the population increased to 8 log CFU/ml.
Finally, S. aureus M031 (6 log CFU/g) was spiked into sushi and kept at 18 and 30°C. Samples were taken at 0, 12, 18, and 24 h to determine the aerobic plate count and enterotoxin production. S. aureus M031 populations increased to 8 log CFU/g in spiked sushi kept at 30°C for 18 h, and analysis for enterotoxin production was positive, and after 24 h of incubation, enterotoxin production tended to increase.
However, S. aureus counts in sushi kept at 18°C increased to 7 log CFU/g after incubation for 24 h but there was no enterotoxin production.
The results revealed that the aerobic plate count and Staphylococcus sp. found in sushi from supermarkets were 3 log CFU/g and 2 log CFU/g less than in sushi from local markets, respectively.
Fifty-one colonies typical of Staphylococcus sp. on Baird Parker agar were examined for morphological and biochemical characteristics, and only two were identified as coagulase-positive S. aureus (M031 and S022). S. aureus M031 and S022 were investigated for enterotoxin production in TSB incubated at 35°C for 24 h, and enterotoxin was analyzed by ELISA (TECRA SET VIA). Only S. aureus M031 incubated for 24 h was able to produce enterotoxin when the population increased to 8 log CFU/ml.
Finally, S. aureus M031 (6 log CFU/g) was spiked into sushi and kept at 18 and 30°C. Samples were taken at 0, 12, 18, and 24 h to determine the aerobic plate count and enterotoxin production. S. aureus M031 populations increased to 8 log CFU/g in spiked sushi kept at 30°C for 18 h, and analysis for enterotoxin production was positive, and after 24 h of incubation, enterotoxin production tended to increase.
However, S. aureus counts in sushi kept at 18°C increased to 7 log CFU/g after incubation for 24 h but there was no enterotoxin production.
Authors
P. Tiengpittayagorn , O. Chunhachart
Keywords
Staphylococcus aureus, enterotoxin, sushi
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