Development of two multiplex polymerase chain reactions for the detection of enterotoxigenic strains of Staphylococcus aureus isolated from foods.
Two multiplex polymerase chain reactions were developed for the detection of enterotoxigenic strains of Staphylococcus aureus: one multiplex reaction for the simultaneous detection of enterotoxigenic strains type A (entA), type B (entB), and type E (entE) and another for the simultaneous detection of enterotoxigenic strains type C (entC) and type D (entD). Both reactions were standardized with the use of the reference enterotoxigenic strains of S. aureus: FRI 722, producer of staphylococcal enterotoxin (SE) type A (SEA); FRI 1007, producer of SEB; FRI 137, producer of SEC1; FRI 472, producer of SED; and FRI 326, producer of SEE. Optimized methods were used to determine the presence of enterotoxigenic types for 51 S. aureus strains isolated from meat (sausage, ham, and chorizo) and dairy (powdered milk and cheese) products by the Baird-Parker technique. The enterotoxigenic capacities of the strains were determined by the indirect enzyme-linked immunosorbent assay (ELISA) with the use of reference staphylococcal toxins and antitoxins. Fifty of the 51 strains isolated were enterotoxigenic and produced one to four enterotoxin types, with the most frequently produced types being SEA and SED. Levels of correlation between the presence of genes that code for the production of SE (as determined by polymerase chain reaction) and the expression of these genes (as determined by the indirect ELISA) were 100% for SEA and SEE, 86% for SEC, 89% for SED, and 47% for SEB.
Nájera-Sánchez
Gabriela
G
Microbiology Department, Escuela Nacional de Ciencias Biológicas, Instituto Politècnico Nacional, Prolongación de Carpio y Plan de Ayala, Casco de Santo Tomás, C.P. 11340, México, DF. gabyns@yahoo.com
Maldonado-Rodríguez
Rogelio
R
Ruíz Olvera
Patricia
P
de la Garza
Lydia Mota
LM
D000818:Animals; D001483:Base Sequence; D004269:DNA, Bacterial / Q000032:analysis; D003611:Dairy Products / Q000382:microbiology*; D004768:Enterotoxins / Q000145:classification / Q000302:isolation & purification*; D005516:Food Microbiology; D008460:Meat / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013211:Staphylococcus aureus / Q000737:chemistry / Q000235:genetics*; D013552:Swine
D004269:DNA, Bacterial; D004768:Enterotoxins; C049463:enterotoxin E, Staphylococcal; C019368:enterotoxin D, Staphylococcal; C026066:enterotoxin A, Staphylococcal; C034959:enterotoxin C, staphylococcal