A Multiple Superantigenic Toxin Pattern of Methicillin-resistant Staphylococcus aureus (MRSA) as a Risk Factor in the Development of Toxic Shock Syndrome (TSS)

Methicillin-resistant Staphylococcus aureus (MRSA), an important cause of nosocomial infections, produces a number of superantigenic toxins such as toxic shock syndrome toxin (TSST)-1 and staphylococcal enterotoxin (SE) C in many cases. However, toxic shock syndrome (TSS) only rarely occurs in MRSA infections. In this study, we isolated MRSA strains from the stool and sputum of a patient with TSS and characterized the molecular nature of the TSS-associated MRSA strains. The two MRSA strains were indistinguishable from each other, as demonstrated by pulsed-field gel electrophoresis. The coagulase type was type 2. The two MRSA strains manifested a multiple superantigenic toxin (MST) pattern of TSST-1, SEA, SEC, SEG, SEH, SEI, and SET in the PCR assay, unlike the previously characterized MRSA strains that lacked (e. g.) SEA. When human peripheral blood mononuclear cells were stimulated with superantigenic toxins, a combination of TSST-1, SEA, and SEC induced much higher levels of cytokine production than did the individual toxin or combination of (e. g.) TSST-1 and SEC. The data suggest that the MST pattern of MRSA could be a risk factor in the development of TSS.