Acute tonsillitis is an acute infection of the palatine tonsils resulting in a sore throat. It can be of viral or bacterial cause. Viral causes are more common. Most cases are self-limiting and don’t require antibiotics. Children aged 5-15 years are more commonly affected. However, it is important to remember that the majority of sore throats are not caused by tonsillitis.

• Viral
  • Tonsillitis is usually viral.
  • Rhinovirus, coronavirus and parainfluenza virus (ordered from most to least common) account for 25% of all sore throats
  • Adenovirus (4%)
  • Influenza virus type A and B (4%)
  • Herpes simplex virus (2%)
  • Epstein-Barr virus (glandular fever; 1%).
• Bacterial
  • Group A ß–haemolytic streptococci (20% in children; 10% in adults)
  • Group C ß–haemolytic streptococci (5%)
  • Rarer bacterial causes: Mycoplasma pneumonia and Neisseria gonorrhoea.

Acute tonsillitis is the inflammatory infection of the palatine tonsils:

• Micro-organisms which successfully penetrate the tonsillar epithelium are phagocytosed by macrophages.
• Macrophages then process and present them to B and T cells within the tonsils, thus stimulating cellular and humoral immune responses.
• Inflammatory cytokines (e.g. phospholipase A2) are produced.
  • Such local inflammatory pathways destroy the virus or bacteria, cause pyrexia and result in oropharyngeal swelling, pain and erythema.

Patients typically present with a combination of an acute onset of:

• Sore throat (99%)
• Fever >38ºC (82%)
• Dysphagia (66%)
• Nasal congestion, headache, earache, cough (47%)
  • These 4 symptoms may be present if viral aetiology.
  • If no cough is present, this is more likely bacterial cause.

Examination of the pharynx may reveal:

• Severely inflamed tonsils (87%)
• Painfully enlarged anterior cervical lymph nodes (49%)
• Purulent tonsils (41%)
  • Pus on the tonsils is suggestive of bacterial cause.

Do not examine if epiglottitis suspected.

• Additional features suggestive of epiglottitis:
  • A young child
  • A muffled voice
  • Excessive drooling and pooling of saliva.
• Call for an anaesthetist and an ENT surgeon.

Acute tonsillitis is usually a clinical diagnosis.

• Investigations are only used if confirmation of group A streptococcal (GAS) infection is required (e.g. in patients on immunosuppression, very old or young, with severe symptoms).
  • In these patients, the NICE 2018 Clinical Knowledge Summary suggests performing a rapid antigen test for GAS.
  • If this antigen test is negative, a throat culture should be performed.

In all other patients, clinical examination in combination with a clinical prediction score (FeverPAIN or Centor - see 'Management' section) should be used to establish the likelihood of GAS infection.

• This is important, as GAS aetiology requires antibiotic treatment.

• Viral upper respiratory tract infection
  • Similarities: sore throat, fever.
  • Differences: coryza, nasal obstruction, facial pain, earache.
• Primary herpes labialis (oral herpes)
  • Similarities: sore throat, fever cervical lymphadenopathy.
  • Differences: mouth pain, burning or tingling, visible vesicles or crusted ulcer.
• Peritonsillar abscess (quinsy)
  • Can be a complication of tonsillitis.
  • Similarities: sore throat, high fever, dysphagia.
  • Differences: trismus (lockjaw), muffled voice, uvular deviation, unilateral enlarged and displaced tonsil.
• Infectious mononucleosis
  • Similarities: sore throat, fever, lymphadenopathy.
  • Differences: does not resolve after 1 week, splenomegaly, hepatomegaly, persistent fatigue, weight loss.
• Epiglottitis
  • An airway emergency. Can be life-threatening due to airway obstruction.
  • Now rare since Haemophilus influenza type B is vaccinated against in routine childhood immunisations.
  • Similarities: sore throat, high fever.
  • Differences: muffled voice, excessive drooling (in children), possible stridor and breathing difficulty.
• Retropharyngeal abscess
  • Collection of pus in the space between the pre-vertebral fascia and the neck constrictor muscles.
  • Can be life-threatening if not identified early.
  • Similarities: sore throat, high fever, dysphagia.
  • Differences: trismus (lockjaw), visible neck swelling, torticollis.
• Gonococcal pharyngitis
  • Similarities: sore throat, high fever, dysphagia.
  • Differences: adolescent and adult patients with history of oral sex (sexually transmitted).
• Primary HIV infection
  • Similarities: sore throat, high fever, lymphadenopathy.
  • Differences: more generalised lymphadenopathy, weight loss, fatigue, malaise, risk factors for HIV.

Reassurance and symptomatic relief advise should be offered to all patients (NICE 2018 guidelines).

• Reassure – symptoms can last for around 1 week, but most people get better within this time without treatment.
• Paracetamol or ibuprofen – for pain or fever.
• Fluids – adequate intake maintained.

Other treatment

• antibiotics are not routinely indicated, but may be indicated if certain criteria are met as below
  • if antibiotics are indicated then either phenoxymethylpenicillin or erythromycin (if the patient is penicillin allergic) should be given. Either a 7 or 10 day course should be given
• there is some evidence that a single dose of oral corticosteroid may reduce the severity and duration of pain, although this has not yet been incorporated into UK guidelines

NICE indications for antibiotics

• features of marked systemic upset secondary to the acute sore throat
• unilateral peritonsillitis
• a history of rheumatic fever
• an increased risk from acute infection (such as a child with diabetes mellitus or immunodeficiency)
• patients with acute sore throat/acute pharyngitis/acute tonsillitis when 3 or more Centor criteria are present

Scoring systems

The Centor criteria are: score 1 point for each (maximum score of 4)

• presence of tonsillar exudate
• tender anterior cervical lymphadenopathy or lymphadenitis
• history of fever
• absence of cough

The FeverPAIN criteria are: score 1 point for each (maximum score of 5)

• Fever over 38°C.
• Purulence (pharyngeal/tonsillar exudate).
• Attend rapidly (3 days or less)
• Severely Inflamed tonsils
• No cough or coryza

Special patient groups:

• If on DMARDs or carbimazole, check FBC urgently.
• If immunosuppressed (eg leukaemia, HIV/AIDS), seek urgent specialist advice.

Complications of acute tonsillitis are rare.

Potential complications include:

• Acute otitis media
  • Common, benign and self-limiting.
  • Antibiotics reduce the risk.
• Peritonsillar abscess (quinsy) or neck abscess
  • Usually in the first 2 months after acute tonsillitis episode.
  • Presents with spiking fever, neck pain and dysphagia.
  • Antibiotics reduce the risk. Drainage required.
• Acute sinusitis
  • In 0.4% of untreated patients.
  • Antibiotics reduce the risk.

These very rare complications usually only occur if an underlying bacterial infection is untreated, and include:

• Scarlet fever
  • Presents as a blanching erythematous papular rash, a strawberry tongue and circumoral pallor.
• Acute rheumatic fever
  • Extremely rare (<1:100,000).
  • Causes widespread inflammation throughout the body.
  • Presents with arthritis, subcutaneous nodules, erythema marginatum, chorea and carditis.
  • Antibiotics reduce the risk.
• Acute post-streptococcal glomerulonephritis:
  • Exceedingly rare.
  • Presents with haematuria, oedema, vomiting and anorexia.
• Streptococcal toxic shock syndrome:
  • Very rare but life-threatening.
  • Presents with progressive multiple organ failure and shock.
  • Due to exaggerated inflammatory response to streptococcal antigens.