This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
Toxic Shock Syndrome is most commonly caused by: March 2005 
Select and explain. 
A. Sterptococcus pneumoniae, B. Staphylococcus aureus, C. Vibrio cholerae, D. Clostridium tetani
B: Staphylococcus aureus
Answer: B: Staphylococcus aureus 
Explanation: Ans. B: Staphylococcus aureus Toxic shock syndrome (TSS) is caused by the reaction of the human immune system to bacterial superantigens. A defect of protective immunity is postulated to be a major risk factor for recurrence of TSS. Superantigens are produced by various species of coagulase-positive staphylococci, most notably Staphylococcus aureus but also the zoonoses Streptococcus suis (common in pigs), Streptococcus mitis (in mice), and Streptococcus agalactiae. Group A beta-hemolytic streptococci notably (Streptococcus pyogenes) also produce superantigens.