What is Bacterial Pharyngitis?
Bacterial pharyngitis is an acute infection of the oropharynx and/or nasopharynx caused by bacteria, most commonly Group A β-hemolytic Streptococcus (Streptococcus pyogenes), which is the only form requiring routine antibiotic treatment. 1
Primary Bacterial Cause
- Group A β-hemolytic Streptococcus (GABHS) accounts for the vast majority of bacterial pharyngitis cases and is the only commonly occurring bacterial pharyngitis for which antibiotic therapy is definitely indicated. 1, 2
- GABHS affects 5-15% of adults and 15-35% of children presenting with pharyngitis. 3
- This organism is primarily a disease of children between 5 and 15 years of age, typically occurring in winter and early spring in temperate climates. 1
Clinical Presentation of GABHS Pharyngitis
The characteristic features include:
- Sudden onset of sore throat with pain on swallowing 1, 2
- Fever, headache, nausea, vomiting, and abdominal pain (especially in children) 1, 2
- Tonsillopharyngeal erythema with or without exudates 1
- Tender enlarged anterior cervical lymph nodes 1, 2
- Additional findings may include beefy red swollen uvula, palatal petechiae, excoriated nares in infants, and scarlatiniform rash 1
Critical Diagnostic Limitation
The signs and symptoms of bacterial and viral pharyngitis overlap so broadly that accurate diagnosis on clinical grounds alone is impossible—laboratory confirmation is mandatory. 1, 2 Even experienced clinicians cannot reliably distinguish GABHS from viral pharyngitis based on clinical examination alone, which is why physicians overdiagnose streptococcal pharyngitis by a wide margin when relying solely on clinical judgment. 4
Other Bacterial Causes (Rare)
While GABHS dominates, other bacteria can occasionally cause pharyngitis:
- Groups C and G β-hemolytic streptococci can cause pharyngitis, but antibiotic benefit for these organisms is unproven. 1, 2
- Very rare but serious pathogens requiring consideration include Corynebacterium diphtheriae, Neisseria gonorrhoeae (in sexually active individuals), Arcanobacterium haemolyticum (particularly in teenagers/young adults, often with scarlet fever-like rash), Francisella tularensis, Yersinia enterocolitica, and mixed anaerobic infections (Vincent's angina). 1, 2
- Mycoplasma pneumoniae and Chlamydia pneumoniae are uncommon causes of acute pharyngitis. 1
Clinical Clues Suggesting Viral Rather Than Bacterial Etiology
The presence of conjunctivitis, cough, hoarseness, coryza, anterior stomatitis, discrete ulcerative lesions, viral exanthem, or diarrhea strongly suggests viral rather than streptococcal etiology. 1, 2, 5
Why Accurate Diagnosis Matters
Distinguishing bacterial from viral pharyngitis is critical because:
- Antimicrobial therapy is of no proven benefit for acute pharyngitis due to bacteria other than Group A streptococcus (with rare exceptions like C. diphtheriae and N. gonorrhoeae). 1
- Unnecessary antibiotic administration exposes patients to expense, adverse effects, and contributes to antibiotic resistance. 1
- Appropriate antibiotic treatment of confirmed GABHS prevents acute rheumatic fever, suppurative complications (peritonsillar abscess, cervical lymphadenitis, mastoiditis), reduces symptom duration, decreases infectivity, and allows rapid return to normal activities. 1