What are the key differences in diagnosis and treatment between bacterial and viral sore throat etiologies in patients, particularly in school-age children and young adults?

Bacterial vs. Viral Sore Throat: Key Diagnostic and Treatment Differences

Etiology and Prevalence

The vast majority (65-85%) of acute sore throat cases are viral in origin, while bacterial causes—primarily Group A β-hemolytic streptococcus (GABHS)—account for only 15-30% in children and 5-15% in adults. 1

Viral Causes

• Respiratory viruses are the most frequent culprits, including rhinovirus, coronavirus, adenovirus, influenza, parainfluenza, and respiratory syncytial virus 1
• Epstein-Barr virus causes infectious mononucleosis with pharyngitis accompanied by generalized lymphadenopathy and splenomegaly 1
• Viral pharyngitis is self-limiting, typically resolving within 7 days without antibiotics 1

Bacterial Causes

• Group A β-hemolytic streptococcus (Streptococcus pyogenes) is the most common bacterial cause requiring antibiotic therapy 1
• Groups C and G β-hemolytic streptococci can cause pharyngitis with milder clinical presentation 1
• Peak incidence occurs in children 5-15 years of age during winter and early spring (November-May) 2

Clinical Differentiation

Clinical features alone cannot reliably distinguish GABHS from viral pharyngitis—microbiological confirmation with throat culture or rapid antigen detection test (RADT) is required when GABHS is suspected. 1

Features Strongly Suggesting Viral Etiology

• Conjunctivitis, cough, hoarseness, or coryza (runny nose) 1
• Diarrhea, anterior stomatitis, or discrete ulcerative lesions 1
• Viral exanthem (rash) 1
• Do not test or treat these patients with antibiotics 2

Features Suggesting Bacterial (GABHS) Pharyngitis

• Sudden-onset sore throat with fever 1
• Tonsillar exudates (yellow pus on tonsils) 1
• Tender anterior cervical adenopathy (swollen, painful neck lymph nodes) 1
• Absence of cough 1
• Patient age 5-15 years 1

Diagnostic Algorithm Using Centor Criteria

Use the Centor criteria to determine which patients need laboratory testing, but never treat based on clinical score alone—always confirm with RADT or throat culture before prescribing antibiotics. 3

Centor Criteria Scoring (1 point each):

• Fever (temperature >38°C/100.4°F) 3
• Absence of cough 3
• Tender anterior cervical lymphadenopathy 3
• Tonsillar swelling or exudate 3

Testing Strategy Based on Score:

• Score 0-1: Very low probability of GABHS—do not test, treat symptomatically with analgesics only 3
• Score 2-3: Perform RADT or throat culture; backup culture recommended for children and adolescents due to lower RADT sensitivity in pediatrics 3
• Score 4: High probability of GAS, but laboratory confirmation is still recommended before treatment, as even patients with all clinical features have confirmed streptococcal pharyngitis only 35-50% of the time 3

Age-Specific Testing Considerations:

• Children <3 years: Do not test routinely, as GABHS pharyngitis is uncommon and acute rheumatic fever is exceptionally rare in this age group 3
• Children 5-15 years: Peak testing age, when GABHS causes 15-30% of acute pharyngitis cases 3
• Adults: Lower disease prevalence (5-15%), making the threshold for testing appropriately higher 3

Treatment Differences

Viral Pharyngitis Management

• Either ibuprofen or paracetamol (acetaminophen) are the most effective treatments available for symptom relief 1
• Antibiotics provide no benefit and should not be prescribed 2
• Zinc gluconate is not recommended 2
• Herbal treatments and acupuncture have inconsistent evidence and cannot be reliably recommended 2

Bacterial (GABHS) Pharyngitis Management

Penicillin V is first-line therapy, with a dosage of 250 mg twice or three times daily for 10 days. 2, 3

Antibiotic Benefits:

• Modest symptom relief, shortening duration by 1-2 days 3
• Prevention of acute rheumatic fever (when treated within 9 days of symptom onset) 3
• Prevention of suppurative complications (peritonsillar abscess, acute otitis media) 3
• Reduction of disease transmission to close contacts 3

Alternative Antibiotics for Penicillin Allergy:

• First-generation cephalosporins 3
• Clindamycin 3
• Clarithromycin or azithromycin 3

Critical Pitfall to Avoid

Antibiotics should not be used in patients with less severe presentations (0-2 Centor criteria) to relieve symptoms, and should not be prescribed to prevent rheumatic fever or acute glomerulonephritis in low-risk patients (those without previous history of rheumatic fever). 2

• Nationally, up to 70% of patients with sore throats receive prescriptions for antimicrobials, while only 20-30% are likely to have GABHS pharyngitis 2
• Physicians often greatly overestimate the probability that GABHS is the cause of pharyngitis 2
• The modest benefits of antibiotics in confirmed GABHS-positive patients must be weighed against side effects, effects on the microbiota, increased antibacterial resistance, medicalization, and costs 2

When to Seek Immediate Evaluation

• Severe difficulty swallowing or breathing 1
• Unilateral tonsillar swelling with uvular deviation (peritonsillar abscess) 4
• Neck stiffness, drooling, or severe difficulty swallowing (retropharyngeal abscess) 4
• Stridor, sitting forward position, or respiratory distress (epiglottitis—airway emergency) 4
• Sore throat lasting beyond 2 weeks warrants evaluation for non-infectious causes and serious pathology 4