What is pharyngitis?

What is Pharyngitis?

Pharyngitis is an acute inflammatory condition of the oropharynx and/or nasopharynx characterized by sore throat, with the majority of cases caused by viral infections, though Group A β-hemolytic Streptococcus (GAS) represents the most important bacterial cause requiring antibiotic treatment. 1

Definition and Clinical Presentation

Pharyngitis presents as an inflammatory syndrome affecting the pharynx, typically manifesting as:

• Sore throat (often with sudden onset in bacterial cases) that worsens with swallowing 1
• Fever of varying degrees (typically 101°F to 104°F in GAS pharyngitis) 1
• Tonsillopharyngeal erythema with or without exudates 1
• Headache, nausea, vomiting, and abdominal pain (especially in children) 1

Etiologic Agents

Viral Causes (Majority of Cases)

Viruses account for the vast majority of acute pharyngitis cases, including 1:

• Respiratory viruses: rhinovirus, coronavirus, adenovirus, influenza virus, parainfluenza virus, respiratory syncytial virus
• Epstein-Barr virus (causing infectious mononucleosis with generalized lymphadenopathy and splenomegaly) 1
• Enteroviruses, herpesviruses, and coxsackievirus 1

Bacterial Causes

Group A β-hemolytic Streptococcus (Streptococcus pyogenes) is the most common bacterial cause, accounting for 25-40% of cases in children and 10-25% in adults, with peak incidence between ages 5-15 years 1:

Less common bacterial causes include 1:

• Groups C and G β-hemolytic streptococci
• Neisseria gonorrhoeae (in sexually active individuals)
• Corynebacterium diphtheriae (rare but serious)
• Arcanobacterium haemolyticum
• Mycoplasma pneumoniae and Chlamydia pneumoniae

Epidemiological Features

GAS pharyngitis demonstrates characteristic epidemiological patterns 1:

• Age distribution: Primarily affects children 5-15 years of age; uncommon in children under 3 years 1
• Seasonal pattern: Winter and early spring predominance in temperate climates 1
• Transmission: Close contact with documented cases increases risk 1

Clinical Differentiation: A Critical Pitfall

The signs and symptoms of bacterial and viral pharyngitis overlap so broadly that accurate diagnosis on clinical grounds alone is impossible, even for experienced clinicians 1. This represents the most important clinical pitfall in pharyngitis management.

Features Suggesting Viral Etiology

Clinical findings highly suggestive of viral pharyngitis include 1:

• Cough, coryza (nasal congestion), and hoarseness
• Conjunctivitis
• Diarrhea
• Discrete ulcerative lesions or characteristic viral exanthems/enanthems

Features Suggesting Bacterial (GAS) Etiology

Clinical findings suggestive of GAS pharyngitis include 1:

• Sudden-onset sore throat with pain on swallowing
• Fever without cough
• Tonsillar exudates
• Tender, enlarged anterior cervical lymph nodes
• Soft palate petechiae ("doughnut" lesions)
• Beefy red, swollen uvula
• Scarlatiniform rash

However, none of these clinical manifestations individually is specific enough to diagnose GAS pharyngitis 1.

Diagnostic Approach

Microbiological confirmation with either throat culture or rapid antigen detection test (RADT) is required for diagnosis of GAS pharyngitis 1. The algorithmic approach is:

1. Initial clinical assessment to identify obvious viral features (cough, coryza, conjunctivitis, diarrhea) 1, 2
2. If viral features predominate: No testing needed; antibiotics not indicated 1, 2
3. If bacterial features present or unclear: Perform RADT or throat culture 1
4. In children/adolescents with negative RADT: Confirm with throat culture (gold standard) 2

Clinical Significance and Complications

The importance of accurate GAS diagnosis stems from potential complications 1:

• Acute rheumatic fever (preventable with appropriate antibiotic treatment, though risk is extremely low in industrialized countries) 1
• Suppurative complications: peritonsillar abscess, cervical lymphadenitis, mastoiditis (rare, approximately 1% incidence) 1
• Acute glomerulonephritis (rarely follows GAS pharyngitis; antibiotics do not prevent) 1

Natural History

Even untreated, GAS pharyngitis generally improves within 3-4 days, though this does not eliminate the risk of rheumatic fever 1. Viral pharyngitis is typically self-limited, resolving in 7-10 days 1.

Key Clinical Pitfalls to Avoid

• Never rely on clinical presentation alone to diagnose GAS pharyngitis without microbiological confirmation 1
• Do not prescribe antibiotics for viral pharyngitis, as they provide no benefit and expose patients to unnecessary risks 1
• Recognize that positive throat cultures may reflect chronic GAS colonization rather than acute infection 1
• Understand that at least one-third of acute rheumatic fever cases result from inapparent streptococcal infections, making complete prevention impossible 1