Acute tonsillitis

What it is

Acute tonsillitis is inflammation of the pharyngeal tonsils. Group A beta-haemolytic streptococcus is the most commonly infecting organism, and Streptococcus is named as the most common organism. Peak incidence of the GAS infection is between the ages of 5 and 12.

How it presents

Onset is rapid. Fever, sore throat, headache, nausea, vomiting, dysphagia and abdominal pain make the picture. On examination the tonsils are congested, often with white follicles, and the anterior cervical nodes are palpable; the tonsils will often meet in the midline and may be covered with a membrane.

Grades of tonsillar hypertrophy:

• Grade 0: tonsil in palatine fossa.
• Grade 1: tonsil occupying < 25% of oropharynx.
• Grade 2: tonsil occupying 25 - 50% of oropharynx.
• Grade 3: tonsil occupying 50-75% of oropharynx.
• Grade 4: tonsil occupying > 75% of oropharynx.

How it is diagnosed

The work is to distinguish GAS pharyngitis from non-GAS pharyngitis. Throat culture and the rapid antigen detection test do that; a throat swab, RADT or Monospot test are the ones sent when suspicion is raised.

The Centor criteria give the likelihood of haemolytic GAS. Fever scores one, the absence of cough scores one, and anterior cervical lymphadenopathy scores one, so fever with no cough and anterior cervical lymphadenopathy is 3 out of 4. That score indicates the infection is likely to be bacterial rather than viral, and so requires antibiotics.

A membrane over the tonsil raises its own differential: membranous tonsillitis, diphtheria, and infectious mononucleosis. A patient who is systemically well is unlikely to have diphtheria. Petechial haemorrhage on the palate together with splenomegaly points to infectious mononucleosis, where the blood film shows atypical lymphocytosis and the Monospot and Paul-Bunnell tests are used.