NBEO Microbiology Practice Test

Toxic shock syndrome is most strongly linked to a bacterium that is coagulase positive and produces a potent superantigen toxin. Staphylococcus aureus fits this description because it makes TSST-1, a toxin that acts as a superantigen and triggers a massive release of cytokines, leading to fever, rash, and shock. The coagulase test distinguishes this organism from other common Gram-positive cocci. Staphylococcus epidermidis is coagulase negative and typically causes device-related or opportunistic infections rather than toxic shock. Streptococcus pyogenes can cause a toxic shock–like syndrome, but it is not coagulase positive, and the classic toxic shock mechanism differs. Streptococcus pneumoniae is not associated with toxic shock and is not coagulase positive. So the organism that accounts for both toxic shock syndrome and coagulase positivity is Staphylococcus aureus.