The basics - Tonsillitis

Antibiotics should not be prescribed routinely. By Dr Caroline Taylor-Walker

A cause of bacterial tonsilitis is group A beta haemolytic streptococcus (Photograph: DR P. Marazzi / SPL)
A cause of bacterial tonsilitis is group A beta haemolytic streptococcus (Photograph: DR P. Marazzi / SPL)

Tonsillitis is an inflammation of the pharyngeal tonsils, caused by either by bacteria or viruses.

The commonest bacterial cause is group A beta haemolytic streptococcus (GABHS), which typically affects children and causes 15-30 per cent of cases.1

The majority of cases are caused by viruses (rhinovirus and adenovirus). Tonsillitis is very common. A GP list of 2,000 patients will see 120 cases a year.

1. Differential diagnosis
Infectious mononucleosis (glandular fever) is a self-limiting illness caused by the Epstein Barr virus and common in 15- 25-year-olds. It presents with sore throat and fatigue other signs include palatal petechiae, uvula oedema, lymphadenopathy and hepatosplenomegaly.

Coxsackie virus causes painful blisters on the tonsils and roof of the mouth. It typically affects children under 16 years.

Epiglottitis is a medical emergency, caused by Haemophilus influenzae. It presents as a severe sore throat with drooling and sepsis in young children. Throat examinations should only be carried out in a hospital setting.

Malignancy can present as a unilateral enlarged tonsil.

2. Complications
Acute otitis media and sinusitis occur in 0.4 per cent of patients due to bacterial spread.

Quinsy occurs in 2 per cent when tonsillitis progresses to an abscess in the peritonsillar region. It presents with severe throat pain, fever, drooling, trismus and a 'hot potato' voice. NICE recommends urgent admission.

Rheumatic fever occurs in less than one in 100,000 cases, one to three weeks after a sore throat. Glomerulonephritis is a rare complication presenting as an acute nephrotic syndrome two weeks after infection.

3. Diagnosis
Viral infections usually show milder symptoms akin to the common cold. Only 20-30 per cent show classical streptococcal symptoms such as sudden onset of fever, sore throat, swollen glands and red tonsils.

The Centor criteria (tonsillar exudates, tender anterior cervical lymph nodes, no cough, and fever) can help to diagnose GABHS. However, screening using this criteria alone is not recommended as it has a low positive predictive value.2

If three to four criterions are present, there is a 40-60 per cent chance of having GABHS and antibiotics may be beneficial. If less than three are present there is an 80 per cent chance that GABHS is not present and antibiotics are not necessary.

Research has shown that if the patient has three or four of the criteria, they have a one in 60 chance of developing quinsy.2

4. Investigations
Throat swabs and rapid antigen testing are not recommended routinely. Throat swabs cannot distinguish between infection and carriage of GABHS and delay diagnosis.

In addition, six to 40 per cent of people carry the bacteria asymptomatically.2 Rapid antigen testing may be considered in higher risk patients.

5. Management
Antibiotics are not routinely needed as they make little difference to symptoms and can cause adverse reactions and further consultations.2

Explain to the patient that tonsillitis is self-limiting. Symptoms resolve in three days in 40 per cent of patients and within one week in 85 per cent, whether viral or bacterial.2

Advise the patient to minimise social contact and encourage rest and fluids. Suggest paracetamol or ibuprofen for symptom relief.

Antibiotics do reduce the risk of complications. They reduce incidence of otitis media by 25 per cent and sinusitis by 50 per cent. The incidence of complications, such as quinsy, are also reduced. However, 14 patients need antibiotics for one patient to benefit and these complications are rare. 2

Antibiotics should not be prescribed routinely. Consider delayed prescriptions if symptoms do not resolve in three days.

NICE indicates the use of antibiotics if there are features of marked systemic upset, unilateral peritonsillitis, history of rheumatic fever or an increased risk of infection.

Prescribe if the patient is on immunosuppressants. The antibiotic of choice is phenoxymethylpenicillin for 10 days. If the patient is allergic to penicillin or if treatment fails, consider erythromycin for five days. Refer to ENT if there is stridor or respiratory difficulty, dehydration, drooling and inability to swallow or quinsy.

Strict NICE criteria must be met before considering tonsillectomy.3

These are: five or more episodes per year, symptoms lasting for at least a year and episodes that are disabling.

  • Dr Taylor-Walker is a locum GP in Leicestershire.
Signs and symptoms
  • Severe sore throat.
  • Dysphagia.
  • Headache/abdominal pain.
  • Vomiting/halitosis.
  • Red, swollen tonsils.
  • High temperature.
  • Swollen anterior cervical lymph nodes.

1. Emedicine. Tonsillitis & peritonsillar abscess

2. MeReC Bulletin 2006; 17(3): 12-4.

3. NICE. Electrosurgery for tonsillectomy. IPG150. London, NICE, 2005.

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