Synthetic exfoliative toxin A and B DNA probes for detection of toxigenic Staphylococcus aureus strains

Two methods for the detection of exfoliative toxin (ET) from Staphylococcus aureus were compared: (i) a phenotypic assay, electrosyneresis, and (ii) a genotypic assay, staphylococcal DNA hybridization with oligodeoxynucleotide probes. The probes were chosen from the previously determined sequences of serotype A and B of ET, one probe for serotype A and another for serotype B. Strains exhibiting ET production in electrosyneresis always possessed the ET gene(s). Conversely, some strains not exhibiting ET production in electrosyneresis harbored the ET gene(s). The latter strains produced levels of ET. ET-negative phage group 2 strains of S. aureus as well as tested coagulase-negative staphylococci did not possess the ET gene(s). The sensitivity of the DNA hybridization technique was 10(6) bacteria or 100 ng of genomic DNA.