TY - JOUR
T1 - Staphylococcal enterotoxin D production by Staphylococcus aureus FRI 100
AU - Kauffman, N. M.
AU - Roberts, R. F.
PY - 2006/6
Y1 - 2006/6
N2 - Staphylococcus aureus FRI 100 is commonly used as a control strain for staphylococcal enterotoxin A (SEA) assays. When FRI 100 was used in PCR-based enterotoxin detection methods, the strain gave a positive result for both SEA and staphylococcal enterotoxin D (SED). Production of SED was confirmed by testing concentrated and unconcentrated culture supernatants with the TECRA staphylococcal enterotoxin visual immunoassay. SED was detected after 24 h of growth in Trypticase soy broth. Primers were created to amplify the entire sed gene by PCR for subsequent sequencing. The sequenced gene showed high similarity to a previously sequenced sed gene. The SED-like gene in FRI 100 exhibited four point mutations and two deletions. Changes in the FRI 100 open reading frame altered the primary structure of the SED-like protein, allowing for coding of only the first 150 amino acids followed by a stop codon. Because the SED active site is at the proximal end, where there was no change in DNA sequence, we conclude FRI 100 produces a variant form of SED. It is necessary to note that, when using FRI 100 as an SEA control strain, it does produce a variant of the SED protein, which exhibits immunological activity, and the sed-like gene is detected by commonly used PCR primers. This phenomenon may be an important general consideration when using PCR to characterize strains of toxin-producing S. aureus. S. aureus enterotoxin-positive PCR results should be confirmed by immunological techniques.
AB - Staphylococcus aureus FRI 100 is commonly used as a control strain for staphylococcal enterotoxin A (SEA) assays. When FRI 100 was used in PCR-based enterotoxin detection methods, the strain gave a positive result for both SEA and staphylococcal enterotoxin D (SED). Production of SED was confirmed by testing concentrated and unconcentrated culture supernatants with the TECRA staphylococcal enterotoxin visual immunoassay. SED was detected after 24 h of growth in Trypticase soy broth. Primers were created to amplify the entire sed gene by PCR for subsequent sequencing. The sequenced gene showed high similarity to a previously sequenced sed gene. The SED-like gene in FRI 100 exhibited four point mutations and two deletions. Changes in the FRI 100 open reading frame altered the primary structure of the SED-like protein, allowing for coding of only the first 150 amino acids followed by a stop codon. Because the SED active site is at the proximal end, where there was no change in DNA sequence, we conclude FRI 100 produces a variant form of SED. It is necessary to note that, when using FRI 100 as an SEA control strain, it does produce a variant of the SED protein, which exhibits immunological activity, and the sed-like gene is detected by commonly used PCR primers. This phenomenon may be an important general consideration when using PCR to characterize strains of toxin-producing S. aureus. S. aureus enterotoxin-positive PCR results should be confirmed by immunological techniques.
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U2 - 10.4315/0362-028X-69.6.1448
DO - 10.4315/0362-028X-69.6.1448
M3 - Article
C2 - 16786872
AN - SCOPUS:33745079305
SN - 0362-028X
VL - 69
SP - 1448
EP - 1451
JO - Journal of food protection
JF - Journal of food protection
IS - 6
ER -