Which organisms are most commonly involved in the pathogenesis of peritonsillar abscess?

• A. Streptococcus pyogenes (GABHS), Staphylococcus aureus, and polymicrobial anaerobes.
• B. Escherichia coli.
• C. Neisseria meningitidis.
• D. Pseudomonas aeruginosa.

Answer: (A)

Peritonsillar abscess results from infection that spreads from the tonsillar area into the peritonsillar space, so the usual bugs reflect the oropharyngeal flora. The most common offenders are Streptococcus pyogenes (group A streptococcus), Staphylococcus aureus, and a mix of anaerobic bacteria such as Fusobacterium, Bacteroides/Prevotella, and Peptostreptococcus. This combination—aerobic strep and staph with polymicrobial anaerobes—explains why treatment needs to cover both aerobic and anaerobic organisms. In contrast, organisms like Escherichia coli, Neisseria meningitidis, or Pseudomonas aeruginosa are not typical primary pathogens for uncomplicated peritonsillar abscess, as they do not represent the usual oropharyngeal flora involved in this infection.