Chromosomal and extrachromosomal synthesis of exfoliative toxin from Staphylococcus hyicus

Evidence for the existence of two molecular species of exfoliative toxin (E T) synthesized by Staphylococcus hyicus (SHET) under chromosomal and plasmi d control is presented. Serological evidence that these molecular species o f toxins are distinct from each other is given. The molecular weights of SH ET from plasmidless strain P-1 (SHETA) and from plasmid-carrying strains P- 10 and P-23 (SHETB) were almost equal. Both of the serotypes of SHET exhibi ted exfoliation in 1-day-old chickens. The plasmid-cured (P-) substrains (P -23C1 and P-23C2) of S. hyicus P-23 did not cause exfoliation in 1-day-old chickens, whereas P- substrains (P-10C1 and P-10C2) of strain P-10 caused e xfoliation, but they decreased their exfoliative activity. These findings s uggest that SHETB was synthesized along with SHETA by strain P-10, whereas the P-23 strain synthesized SHETB alone. The plasmid-carrying strain (P-23) as well as the plasmidless strain (P-1) exhibited the typical clinical sig ns of exudative epidermitis in pigs. However, plasmid-cured (P-) substrains of P-23 (P23C1 and P23C2) did not exhibit the typical clinical signs of ex udative epidermitis. These findings suggest that SHETA is synthesized under chromosomal control and SHETB is synthesized under plasmid control and tha t SHET-producing strains can be divided into three groups: SHETA-producing strains, SHETB-producing strains, and strains producing both toxins.