Causes of Pharyngitis in Children
Viral Etiologies (Most Common)
Viruses are the most common cause of acute pharyngitis in children, accounting for the majority of cases. 1, 2
Common Viral Pathogens
- Respiratory viruses including adenovirus, parainfluenza virus, rhinovirus, and respiratory syncytial virus are the most frequent viral causes 1, 2
- Enteroviruses such as coxsackievirus and ECHO viruses commonly cause pharyngitis 1
- Herpes simplex virus is another important viral agent 1, 2
- Epstein-Barr virus frequently causes acute pharyngitis accompanied by generalized lymphadenopathy and splenomegaly (infectious mononucleosis) 1, 2
- Systemic viral infections with measles virus, cytomegalovirus, rubella virus, and influenza virus may present with pharyngitis 1
Bacterial Etiologies
Group A β-Hemolytic Streptococcus (Most Important Bacterial Cause)
Group A streptococcus (Streptococcus pyogenes) is the most common bacterial cause of pharyngitis and the only one for which antibiotic therapy is definitively indicated. 1, 3
- Accounts for 15-30% of acute pharyngitis cases in children aged 5-15 years 2, 4
- Primarily affects children between 5 and 15 years of age, with peak incidence in winter and early spring in temperate climates 1, 2
- This is the only commonly occurring form of acute pharyngitis for which antibiotic therapy is definitely indicated, making it the critical diagnostic distinction 1
Other Bacterial Causes (Uncommon)
- Groups C and G β-hemolytic streptococci can cause acute pharyngitis but are less common 1, 2
- Arcanobacterium haemolyticum causes pharyngitis with a scarlet fever-like rash, particularly in teenagers and young adults, though rarely recognized in the United States 1, 5
- Corynebacterium diphtheriae is a rare cause 1
- Neisseria gonorrhoeae can occasionally cause pharyngitis in sexually active individuals 1
- Rare bacterial causes include Francisella tularensis, Yersinia enterocolitica, and mixed anaerobic infections (Vincent's angina) 1
Atypical Bacterial Pathogens (Uncommon)
- Mycoplasma pneumoniae and Chlamydia pneumoniae are uncommon causes of acute pharyngitis 1
Clinical Significance
The key clinical decision when evaluating a child with acute pharyngitis is determining whether the infection is caused by Group A β-hemolytic streptococcus, as this is the only common etiology requiring antibiotic treatment. 1, 3
- Most cases of acute pharyngitis in children are viral, benign, and self-limited 6, 3
- Distinguishing viral from bacterial (GAS) pharyngitis is crucial to minimize unnecessary antimicrobial use 3
- Clinical features alone cannot reliably differentiate viral from bacterial pharyngitis; microbiological confirmation is required 2, 5
Important Caveats
- 10-15% of school-age children are asymptomatic GAS carriers, so a positive test does not always indicate active infection 7
- The presence of cough, rhinorrhea, hoarseness, or conjunctivitis strongly suggests viral etiology and argues against bacterial infection 1, 2, 7
- Testing should not be performed when obvious viral features are present, as this frequently identifies asymptomatic carriers and leads to unnecessary antibiotics 2, 7