Detection of genes for enterotoxins (ent) and toxic shock syndrome toxin-1 (tst) in mammary isolates of Staphylococcus aureus by polymerase-chain-reaction

During a two-year-period (1997-1998) 94 held strains of Staphylococcus aureus isolated from cases of bovine mastitis were investigated for the presence of genes for staphylococcal enterotoxin (ent) and toxic shock syndrome toxin-l (TSST-1; tst). Polymerase-chain reaction (PCR) was performed using six pairs of relevant oligonucleotide primers. Thirty-four isolates were positive for one (18 strains) or two (16 strains) toxin genes. Three held strains were positive for enterotoxin A gene (sea), two for enterotoxin B gene (seb), 22 for enterotoxin C gene (sec), four for enterotoxin D gene (sed) and 19 for TSST1 gene (tst). The enterotoxin E gene (see) sequence was not found. The combination of sec and tst showed the highest incidence. A high correlation between PCR results and toxin protein detection by a commercial enzyme linked immunosorbent assay (ELISA) system and a reversed passive latex-agglutination (RPLA) test was observed. In these immunoassays, only one strain of S. aureus produced equivocal results for production of enterotoxin A, giving an overall concordance between genotypic and phenotypic identification of 98.9%. (C) 2001 Elsevier Science Ltd. All rights reserved.