SELECTIVE ENTEROTOXIN PRODUCTION IN FOODS BY STAPHYLOCOCCUS-AUREUS STRAINS THAT PRODUCE MORE THAN ONE ENTEROTOXIN

Staphylococcus aureus strain S-6, producer of enterotoxins A and B-, s train FRI-913, producer of enterotoxins A, C, and E; and strain FRI- 1 96E, producer of enterotoxins A and D, were grown in milk (pH 6.8), po tato salad with mayonnaise, and boiled egg white (pH 8.0-8.5). Enterot oxins were detectable in milk incubated at 26-degrees-C when colony co unts were less than 10(6). Enterotoxin production by strain S-6 was de tectable in potato salad at 10(6) CFU at both 26 and 37-degrees-C. Ent erotoxin A production by strain FRI-913 was detectable at approximatel y 10(6) CFU/g, whereas enterotoxin C was detectable only when growth r eached approximately 10(8) CFU/g. Production of enterotoxins A and D b y strain FRI-196E was detectable when growth was greater than 10(7) CF U/g. Production of enterotoxins A and B by strain S-6 in boiled egg wh ite was detectable at greater than 10(6) CFU/g. In most experiments, e nterotoxins A and C from strain FRI-913 were detectable when cell coun ts were greater than 10(7) CFU/g, whereas enterotoxin A and enterotoxi n D production by strain FRI-196E was detectable at counts between 10( 5) and 10(6) CFU/g. It can be concluded that enterotoxin production is influenced by the time of incubation and the composition and pH of th e food.