Streptococcus pyogenes is commonly associated with which of the following conditions?

• A. Otitis media
• B. Scarlet fever
• C. Relapsing fever
• D. Subacute endocarditis

Answer: (B)

Streptococcus pyogenes is classically linked to scarlet fever when the bacterium produces pyrogenic (erythrogenic) exotoxins during a pharyngitis. These toxins act as superantigens and trigger a widespread, fine, red rash—the telltale sign of scarlet fever—often accompanied by fever, a sore throat, and a “strawberry” tongue. The rash typically begins on the trunk and spreads outward, with desquamation appearing after the rash fades. This toxin-mediated rash is the key link between this organism and scarlet fever.

Relapsing fever is caused by Borrelia species, not GAS. Subacute endocarditis is most associated with viridans streptococci, not Streptococcus pyogenes. Otitis media is commonly caused by organisms like Streptococcus pneumoniae or Haemophilus influenzae, though GAS can cause otitis in some cases, it is not the classic association.