Which organism is classically associated with rheumatic fever after streptococcal pharyngitis, with JONES criteria including joints, heart problems, nodules, erythema, and chorea?

Which organism is classically associated with rheumatic fever after streptococcal pharyngitis, with JONES criteria including joints, heart problems, nodules, erythema, and chorea?

• A. Streptococcus pyogenes
• B. Staphylococcus aureus
• C. Streptococcus pneumoniae
• D. Streptococcus agalactiae

Answer: (A)

Rheumatic fever is an autoimmune complication that follows infection with group A Streptococcus (Streptococcus pyogenes) after streptococcal pharyngitis. The major manifestations summarized by the JONES criteria—joint involvement, carditis, subcutaneous nodules, erythema marginatum, and chorea—reflect an inflammatory, immune-mediated process rather than direct infection. The key idea is molecular mimicry: antibodies against the streptococcal M protein cross-react with cardiac tissue, especially the valves, leading to rheumatic carditis and other systemic features. Because this autoimmune cascade is initiated specifically by the group A streptococcus, Streptococcus pyogenes is the organism classically linked to rheumatic fever after pharyngitis. Other bacteria listed—Staphylococcus aureus, Streptococcus pneumoniae, and Streptococcus agalactiae—do not drive this autoimmune post-strep syndrome.

Rheumatic fever is an autoimmune complication that follows infection with group A Streptococcus (Streptococcus pyogenes) after streptococcal pharyngitis. The major manifestations summarized by the JONES criteria—joint involvement, carditis, subcutaneous nodules, erythema marginatum, and chorea—reflect an inflammatory, immune-mediated process rather than direct infection. The key idea is molecular mimicry: antibodies against the streptococcal M protein cross-react with cardiac tissue, especially the valves, leading to rheumatic carditis and other systemic features. Because this autoimmune cascade is initiated specifically by the group A streptococcus, Streptococcus pyogenes is the organism classically linked to rheumatic fever after pharyngitis. Other bacteria listed—Staphylococcus aureus, Streptococcus pneumoniae, and Streptococcus agalactiae—do not drive this autoimmune post-strep syndrome.