Etiology – bacterial “sore throat” Which specific pathogen is the classic cause of bacterial sore throat (acute streptococcal pharyngitis)?

Introduction / Context:
Identifying the classic etiologic agent of acute bacterial pharyngitis guides penicillin therapy and prevention of immune-mediated sequelae. The prototypical organism is group A beta-hemolytic Streptococcus.

Given Data / Assumptions:

• Multiple respiratory pathogens are listed, but only one is the classic agent for “strep throat.”

Concept / Approach:

Streptococcus pyogenes expresses adhesins and exotoxins that inflame the pharynx and tonsils. Untreated infections may lead to rheumatic fever or post-streptococcal glomerulonephritis, so accurate recognition is important.

Step-by-Step Solution:

Verification / Alternative check:

Rapid antigen detection tests and throat culture protocols specifically target group A streptococci, reflecting their clinical importance.

Why Other Options Are Wrong:

• Staphylococcus aureus: less typical primary pharyngeal pathogen.
• Haemophilus spp., Moraxella: more associated with otitis/sinusitis or COPD exacerbations.
• Mycoplasma pneumoniae: atypical pneumonia; can cause pharyngitis but not the classic “strep throat.”

Common Pitfalls:

• Treating viral pharyngitis as bacterial; clinical scoring and testing help differentiate.

Final Answer:

Streptococcus pyogenes