LAUSR

Staphylococcal intoxications are often associated with staphylococcal enterotoxins produced by Staphylococcus aureus. However, several studies revealed that other Staphylococcus species, such as S. intermedius and S. warneri, could produce enterotoxins as well. To facilitate the identification of a mixed culture while tracing the causative staphylococci of food poison, a polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) method was developed to differentiate Staphylococcus species using Staphylococcus-specific primers targeting the elongation factor Tu gene (tuf gene). Eleven tested species were differentiated to 10 separated patterns. Variance of the patterns between strains within a species was analyzed using 9 strains of S. aureus and several strains of other species. It was shown that strains within a species migrated the same distance in the DGGE assay. When mixed cultures of different Staphylococcus species in milk were subjected to DNA extraction and PCR-DGGE, the resulted patterns faithfully corresponded to the species of the mixed cultures, including those of potential to secret enterotoxins.