Peritonsillar Abscess



Infectious complication of tonsillitis or pharyngitis resulting in an accumulation of purulence in the tonsillar fossa; also referred to as “quinsy”


  • Most common deep space infection of head and neck
  • Seen most commonly in adolescents but occasionally in younger children

Risk Factors

  • Tonsillitis
  • Pharyngitis

General Prevention

Abscess formation can often be prevented if appropriate antimicrobial therapy is initiated while the infection is still at the cellulitis stage.


  • Infectious tonsillopharyngitis progresses from cellulitis to abscess.
  • The infection starts in the intratonsillar fossa, which is situated between the upper pole and the body of the tonsil and eventually extends around the tonsil.
  • The abscess is a suppuration outside the tonsillar capsule, in proximity to the upper pole of the tonsil, involving the soft palate.
  • Purulence usually collects within one tonsillar fossa but it may be bilateral.
  • The pterygoid musculature may become irritated by pus and inflammation, which leads to the clinical finding of trismus.
  • Tonsillar and peritonsillar edema may lead to compromise of the upper airway.


  • Most abscesses are polymicrobial.
  • Group A β-hemolytic streptococci (GABHS) is the most common bacterium isolated.
  • α-Hemolytic streptococci is the second most common bacterium reported in most studies.
  • Staphylococcus aureus
  • Anaerobic bacteria play an important role:
    • Prevotella
    • Porphyromonas
    • Fusobacterium
    • Peptostreptococcus
  • Possible synergy between anaerobes and GABHS
  • Gram-negatives such as Haemophilus influenzae and, more rarely, Pseudomonas species may be isolated.

Commonly Associated Conditions

  • Tonsillitis or pharyngitis usually precedes its development.
  • Peritonsillar cellulitis is often associated with infectious mononucleosis.

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