What is the difference between tonsillitis and strep throat?

Difference Between Tonsillitis and Strep Throat

Tonsillitis is inflammation of the tonsils that can be caused by various pathogens (viral or bacterial), while strep throat specifically refers to pharyngitis caused by Group A Streptococcus bacteria (Streptococcus pyogenes). 1

Key Differences

Causative Agents

• Tonsillitis:

  • Viral causes: 70-95% of cases 2
  • Bacterial causes: Group A Streptococcus (5-15% in adults, 15-30% in children 5-15 years) 2
  • Other bacterial pathogens may also cause tonsillitis

• Strep Throat:

  • Exclusively caused by Group A β-hemolytic Streptococcus (Streptococcus pyogenes) 1

Clinical Presentation

Tonsillitis Features:

• Inflammation of the tonsils
• Sore throat
• Tonsillar erythema and edema
• May have exudates
• Fever (variable)
• Can be viral or bacterial in origin

Strep Throat Features:

• Sudden onset of sore throat
• Pain with swallowing
• Fever
• Tonsillopharyngeal inflammation
• Patchy tonsillopharyngeal exudates
• Palatal petechiae
• Tender anterior cervical lymph nodes
• Absence of cough, rhinorrhea, hoarseness (which suggest viral etiology) 1

Diagnostic Approach

The clinical features alone cannot reliably differentiate between viral and bacterial causes of tonsillitis or confirm strep throat 1. Laboratory confirmation is essential:

• Rapid antigen detection test (RADT) - A positive result confirms strep throat
• Throat culture - Gold standard for diagnosis of strep throat
  • Backup culture should be performed in children and adolescents with negative RADT
  • Backup culture generally not necessary in adults due to lower incidence of strep throat and lower risk of rheumatic fever 1

Treatment Differences

• Viral Tonsillitis:

  • Supportive care only
  • Analgesics/antipyretics for symptom relief
  • No antibiotics indicated 1

• Bacterial Tonsillitis/Strep Throat:

  • Penicillin V or amoxicillin is the first-line treatment 1
  • For penicillin-allergic patients: cephalexin (if no immediate hypersensitivity), clindamycin, clarithromycin, or azithromycin 1
  • Standard treatment duration is 10 days for most antibiotics (except azithromycin: 5 days) 1, 3

Clinical Implications and Complications

Why Distinguishing Matters

Identifying strep throat specifically is important because:

1. Prevention of complications: Untreated strep throat can lead to:

   • Suppurative complications: peritonsillar abscess, cervical lymphadenitis, mastoiditis 1
   • Non-suppurative complications: acute rheumatic fever, acute glomerulonephritis 1, 2

2. Appropriate antibiotic use: Antibiotics are only effective for bacterial causes and unnecessary for viral infections 1

Common Pitfalls to Avoid

1. Treating based on clinical features alone: Clinical features overlap significantly between viral and bacterial causes 1

2. Overtreatment of viral pharyngitis: Most cases of tonsillitis are viral and do not require antibiotics 2

3. Inadequate testing: Failure to confirm strep throat with appropriate testing (RADT or culture) before prescribing antibiotics 1

4. Confusion between carriers and active infection: Some patients may be streptococcal carriers who develop viral pharyngitis. These patients have positive tests for Group A Streptococcus but don't require antibiotic treatment for their current symptoms 1

5. Inadequate treatment duration: Not completing the full course of antibiotics for confirmed strep throat can lead to treatment failure and complications 1

Algorithm for Evaluation

1. Assess clinical features:

   • Features suggesting strep throat: sudden onset, fever, tonsillar exudates, tender cervical lymph nodes, absence of cough
   • Features suggesting viral etiology: cough, rhinorrhea, hoarseness, conjunctivitis, diarrhea, discrete ulcerative stomatitis

2. Perform appropriate testing:

   • RADT for patients with clinical features suggesting strep throat
   • If RADT positive → treat for strep throat
   • If RADT negative in children/adolescents → perform throat culture
   • If RADT negative in adults → generally no further testing needed

3. Treatment based on results:

   • Confirmed strep throat → appropriate antibiotic therapy
   • Viral or negative tests → supportive care only

By understanding these differences, clinicians can provide appropriate care, reduce unnecessary antibiotic use, and prevent complications of untreated streptococcal infections.