To study the possible presence of staphylococcal enterotoxin A
in raw
goats' milk lactic cheese, milk was inoculated with an enterotoxigenic
Staphylococcus
aureus strain to a final concentration of 4, 5 and 6 log(cfu/ml).
Cheese was prepared
following industrial specifications and ripened for 42 d. Detection of
the enterotoxins
was by the Vidas Staph enterotoxin test (BioMérieux) and by an indirect
double-sandwich ELISA technique using anti-enterotoxin monoclonal antibodies.
Staphylococcal
counts declined markedly after draining, and by the end of ripening they
had disappeared from some cheeses. In contrast, aerobic mesophilic organisms
grew
well. The level of staphylococcal enterotoxin A recovered varied from 1
to 2·5 ng/g
cheese made with an initial population of 105 or
106 cfu/ml. Only traces of
enterotoxin A (0·5 ng/g) were detected in cheeses made
with the lowest Staph. aureus
inoculum used in this study. Enterotoxin A was also detected in cheeses
from which
Staph. aureus had disappeared.