Growth of Staphylococcus aureus and synthesis of enterotoxin during ripening of experimental Manchego-type cheese.
To study the possible presence of staphylococcal enterotoxins in Manchego-type cheese, milk was inoculated with the enterotoxigenic Staphylococcus aureus collection strains FRI-100, S6, FRI-137, and FRI-472 to a final concentration of 10,000 to 25,000 cfu/ml. Cheese was prepared following the industrial specifications and ripened for 60 d. Batches were prepared with 1 and .1% lactic acid culture and labeled with the abbreviated name of the strain and the concentration of lactic acid culture. Mean staphylococcal counts in .1% lactic bacteria cheeses were usually more than 1 log higher than the corresponding 1% ones. Staphylococcal counts declined markedly after d 35 to 42, and, by the end of ripening, they had disappeared from some cheeses. Enterotoxins were present in five of the cheeses, three prepared with .1% and two with 1% lactic bacteria. Enterotoxins detected were A and D, the enterotoxins most commonly associated with human intoxication. The maximum level of enterotoxin A detected in cheese with strain FRI-100 and with the .1% culture was 222 ng/100 g of cheese; in cheese FRI-100 with 1%, 111 ng/100 g; in cheese S6 with .1%, 769 ng/100 g; and in cheese S6 with 1%, 33 ng/100 g. Maximum level of enterotoxin D detected in cheese FRI-472 with .1% was 38 ng/100 g.
Gómez-Lucía
E
E
Departamento de Patologia Animal I, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain.
Goyache
J
J
Orden
J A
JA
Domenech
A
A
Javier Hernandez
F
F
Ruiz-Santa Quiteria
J A
JA
Lopez
B
B
Blanco
J L
JL
Suárez
G
G
D000818:Animals; D002417:Cattle; D002611:Cheese; D015169:Colony Count, Microbial; D004768:Enterotoxins / Q000032:analysis / Q000096:biosynthesis*; D005516:Food Microbiology; D006041:Goats; D006863:Hydrogen-Ion Concentration; D012756:Sheep; D013211:Staphylococcus aureus / Q000254:growth & development* / Q000378:metabolism
D004768:Enterotoxins; C019368:enterotoxin D, Staphylococcal; C026066:enterotoxin A, Staphylococcal