Purification and characterization of a novel Staphylococcus chromogenes exfoliative toxin

Summary Staphylococcus chromogenes strains were isolated in pure culture from six to eight adult pigs affected with exudative epidermitis (EE), while those were isolated from healthy adult pigs, piglets affected with EE and healthy piglets at low rate. The culture filtrates (CFs) of the above isolates caused rounding effect on cultured cells and exfoliation in 1-day-old chickens. The exfoliative toxin was isolated from CF of a strain (PC-16) possessed strong toxic activity and designated S. chromogenes exfoliative toxin (SCET). The SCET was purified by gel filtration on a Sephadex G-75 column, and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The purified SCET caused exfoliation in 1-day-old chickens. The SCET has no caseinolytic protease activity. The SCET was serologically different from S. aureus exfoliative toxins (ETA, ETB and ETC), S. hyicus exfoliative toxins (SHETA and SHETB), and S. intermedius exfoliative toxin (SIET). The molecular weights of SCET (30 kDa) were slightly larger than those of ETs (27 kDa) and SHETs (27 kDa), but almost same as SIET. The SCET caused exfoliation in 1-day-old chickens, but not in suckling mice. The SCET was a heat-stable toxin as well as a S. aureus exfoliative toxin A (ETA). When SCET was inoculated subcutaneously into piglets, the exfoliation were observed in the skin of piglets after 24 h of injection.