Acute Tonsillitis and Pharyngitis

Acute tonsillitis and pharyngitis are inflammation of the tonsils and pharynx respectively. They frequently occur together and are considered a spectrum of the same clinical process. They are predominantly viral in aetiology.

Group A streptococcus is the most clinically important bacterial cause. It carries a risk of suppurative complications and, less commonly in resource rich settings, non suppurative complications including rheumatic fever if untreated.

Aetiology

Viral causes account for the majority of presentations across all age groups. They include rhinovirus, adenovirus, influenza, parainfluenza and Epstein Barr virus (producing infectious mononucleosis).

Group A streptococcus is the predominant bacterial cause, more common in children aged five to fifteen years. Consider other bacterial causes (including gonococcal pharyngitis in sexually active individuals) where the clinical context is suggestive.

The typical presentation is sore throat, odynophagia, tonsillar erythema and enlargement (with or without exudate), and cervical lymphadenopathy. Fever, headache and malaise commonly accompany the local symptoms.

Features suggesting a viral aetiology include cough, coryza, conjunctivitis or hoarseness, and a more gradual onset.

Features suggesting streptococcal infection include absence of cough, presence of fever, tonsillar exudate, and tender anterior cervical lymphadenopathy, particularly in the appropriate age group. Validated clinical scoring systems (such as the Centor criteria) estimate the probability of streptococcal infection and guide testing and treatment decisions.

Features suggesting infectious mononucleosis include marked fatigue, generalised (particularly posterior cervical) lymphadenopathy, splenomegaly and a more prolonged course, particularly in adolescents and young adults.

Red flag features require urgent assessment:

• Trismus, muffled voice, drooling, and unilateral tonsillar swelling with deviation of the uvula suggest peritonsillar abscess.
• Stridor and significant respiratory distress suggest epiglottitis or a deep neck space infection.

Both are emergencies requiring immediate specialist assessment.

Clinical scoring systems (such as the Centor or FeverPAIN criteria) estimate the probability of streptococcal infection and guide the decision on testing and antibiotic treatment. They avoid both under treatment of significant bacterial infection and over treatment of the far more common viral presentations.

Rapid antigen detection testing or throat culture for group A streptococcus is performed where clinical scoring suggests an intermediate or high probability of bacterial infection, rather than applied universally to every presentation of sore throat.

Full blood count and monospot or Epstein Barr virus serology are considered where infectious mononucleosis is clinically suspected, particularly in adolescents and young adults with the characteristic prolonged course and associated lymphadenopathy or splenomegaly.

Further assessment (examination for trismus and uvular deviation, imaging where a deep space infection or abscess is suspected) is directed by specific red flag features rather than performed routinely.

Symptomatic treatment forms the foundation of management regardless of the specific aetiology. It includes adequate hydration, analgesia (paracetamol or a nonsteroidal anti inflammatory drug) and, in some cases, a short course of corticosteroids for severe pain.

Antibiotics are indicated for confirmed or clinically probable streptococcal pharyngitis. Penicillin or amoxicillin is first line, with appropriate alternatives for penicillin allergic patients.

A course of penicillin V for ten days remains standard, given its efficacy in preventing rheumatic fever, which is the rationale for the specific duration recommended.

The rationale for treating confirmed streptococcal infection extends beyond symptomatic benefit to prevention of suppurative complications (peritonsillar abscess, otitis media, sinusitis). In populations at risk it also prevents acute rheumatic fever, though the relevance of this varies with the population and geographical context.

Avoid amoxicillin where infectious mononucleosis is a possibility. A characteristic, though harmless, widespread maculopapular rash develops in a substantial proportion of patients with Epstein Barr virus infection given this antibiotic. Recognising this avoids an incorrect subsequent label of penicillin allergy.

Peritonsillar abscess requires urgent drainage (needle aspiration or incision and drainage) together with antibiotics.

Suspected epiglottitis or a significant deep neck space infection requires immediate specialist airway assessment and management, given the potential for rapid deterioration and airway compromise.

Watchful waiting with delayed or no antibiotic prescription is appropriate for the majority of presentations not meeting criteria for probable streptococcal infection, given the predominantly viral aetiology and generally self limiting course. Give clear safety netting advice on features that should prompt reassessment.