Genes encoding staphylococcal enterotoxins G and I are linked and separated by DNA related to other staphylococcal enterotoxins.

Fifteen randomly selected Staphylococcus aureus isolates, known to carry the staphylococcal enterotoxin (SE) G determinant (seg), were shown to carry the SEI determinant (sei). To determine whether these two genes are linked, two S. aureus strains (FRI445 and FRI572), each containing the seg and sei determinants, were further analyzed. In these strains, sei is located 2,002 bp upstream of seg. Within the intergenic nucleotide sequence are three regions of nucleotide sequence with significant identity to the sequences of other SE genes. Characterization of the DNA regions surrounding the seg and sei determinants will allow a better understanding of the association between these two genes and may explain why they are so frequently observed simultaneously in S. aureus isolates.