Rheumatic heart disease is a result of infection with which organism?

• A. Group A streptococci
• B. Staphylococcus aureus
• C. Pseudomonas aeruginosa
• D. Chlamydia pneumoniae

Answer: (A)

Rheumatic heart disease follows an autoimmune response triggered by infection with group A streptococcus, usually from a throat infection. The body makes antibodies to the bacteria that cross-react with heart tissue due to molecular mimicry, leading to inflammation of the heart valves (often the mitral valve) during rheumatic fever. Over time, repeated inflammation causes scarring and deformity, producing rheumatic heart disease. The other organisms listed cause different infections (for example, Staphylococcus aureus can cause acute endocarditis, while Pseudomonas aeruginosa and Chlamydia pneumoniae are associated with other infections) and do not induce this post-streptococcal autoimmune valvular damage.