In a 6-year-old child presenting with fever, enlarged tonsils with exudate, headache, and abdominal pain, what is the most likely causative organism?

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Group A Streptococcus (GAS) is the Most Likely Cause

In a 6-year-old child presenting with fever, tonsillar exudate, enlarged tonsils, headache, and abdominal pain, Group A β-hemolytic Streptococcus (answer D) is the most likely causative organism. 1, 2, 3

Why This Clinical Picture Points to GAS

Age and Epidemiology

  • This patient falls squarely within the peak age range of 5-15 years, when GAS pharyngitis is most common, accounting for 15-30% of acute pharyngitis cases in children. 1, 2
  • GAS is the most common bacterial cause of pharyngitis in this age group, while viral causes predominate in younger children. 1, 4

Classic Clinical Features Present

The constellation of findings in this case strongly suggests bacterial (specifically GAS) rather than viral etiology:

  • Fever with tonsillar exudate and enlarged tonsils – These are hallmark findings of streptococcal pharyngitis. 1, 3
  • Headache – Commonly reported with GAS pharyngitis and listed as a key clinical feature. 1, 3
  • Abdominal pain – Explicitly recognized by the American Heart Association as a finding that "may occur, especially in children" with GAS pharyngitis, alongside classic throat findings. 2, 3

Absence of Viral Features

Critically, this patient lacks features that would suggest viral pharyngitis:

  • No cough, rhinorrhea (coryza), hoarseness, or conjunctivitis mentioned. 1, 2
  • No discrete oral ulcers or viral exanthem described. 2, 3
  • The presence of these viral features would argue against GAS and make testing unnecessary. 2

Why the Other Options Are Less Likely

RSV (Option A)

  • RSV typically causes lower respiratory tract symptoms (bronchiolitis, wheezing) rather than exudative pharyngitis. 1
  • Would expect cough, rhinorrhea, and respiratory distress—none mentioned here.

Staphylococcus (Option B)

  • Staphylococcus aureus is not a common cause of acute pharyngitis in children. 1
  • When staph causes throat infection, it's usually in the context of peritonsillar abscess or other suppurative complications, not primary pharyngitis.

Rhinovirus (Option C)

  • Rhinovirus is a common viral cause of pharyngitis but typically presents with prominent upper respiratory symptoms (rhinorrhea, cough, hoarseness). 1, 2
  • Exudative tonsillitis with abdominal pain is not characteristic of rhinovirus infection.

Critical Diagnostic Caveat

Even with this highly suggestive clinical picture, microbiological confirmation is mandatory before initiating antibiotics. 1, 2

  • Clinical diagnosis alone—even by experienced physicians—cannot definitively distinguish GAS from viral pharyngitis with sufficient accuracy. 1, 2
  • Perform a rapid antigen detection test (RADT) immediately; a positive result is diagnostic and warrants treatment. 2
  • In children and adolescents, a negative RADT must be followed by throat culture because RADT sensitivity is only 79-88%, and missing GAS risks acute rheumatic fever. 2

Management Algorithm

  1. Obtain throat swab for RADT (and backup culture if RADT negative). 2
  2. If RADT positive: Initiate penicillin V or amoxicillin for 10 days—first-line therapy with zero resistance, proven efficacy in preventing rheumatic fever. 2, 4
  3. If RADT negative: Await throat culture results before treating; provide supportive care (analgesics, hydration) in the interim. 2
  4. Do not treat empirically based on clinical impression alone, as this leads to unnecessary antibiotic use and resistance. 1, 2

Common Pitfalls to Avoid

  • Treating without microbiological confirmation: Even when clinical features are classic, only 35-50% of suspected cases are culture-positive. 2
  • Ignoring abdominal pain as a GAS symptom: This is a recognized feature in children and should not mislead you toward a gastrointestinal diagnosis. 2, 3
  • Assuming all exudative pharyngitis is bacterial: Epstein-Barr virus (infectious mononucleosis) can also cause exudative pharyngitis with fever, but typically includes generalized lymphadenopathy and splenomegaly. 1
  • Failing to complete 10-day antibiotic course: Shorter courses (except azithromycin 5 days) do not reliably eradicate GAS or prevent rheumatic fever. 2

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

2
Guideline

Differentiating Viral and Bacterial Pharyngitis

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

3
Guideline

Physical Examination Findings for Strep Throat

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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