What are the likely causes and recommended management for a patient presenting with a whitish exudate on the pharynx?

Whitish Exudate on Pharynx: Differential Diagnosis and Management

The presence of whitish exudate on the pharynx most commonly indicates either Group A β-hemolytic streptococcal (GABHS) pharyngitis or infectious mononucleosis (Epstein-Barr virus), and the key clinical decision is determining whether bacterial infection requiring antibiotics is present. 1

Primary Differential Diagnosis

Bacterial Causes

• Group A β-hemolytic streptococcus (GABHS) is the most important bacterial cause requiring antibiotic therapy, accounting for 10% of adult cases and 15-30% of pediatric cases presenting with pharyngeal exudate 1
• Groups C and G β-hemolytic streptococci can produce similar clinical presentations with exudate 1
• Corynebacterium diphtheriae causes a characteristic thick gray-white membrane (rare in vaccinated populations) 1
• Arcanobacterium haemolyticum produces exudative pharyngitis with scarlet fever-like rash, particularly in teenagers and young adults 1
• Neisseria gonorrhoeae should be considered in sexually active individuals 1

Viral Causes

• Epstein-Barr virus (infectious mononucleosis) frequently causes exudative pharyngitis accompanied by generalized lymphadenopathy and splenomegaly 1
• Adenovirus commonly produces pharyngeal exudate 1
• Other respiratory viruses (parainfluenza, respiratory syncytial virus) can occasionally cause exudate 1

Fungal Causes

• Candida species produce white patches/plaques that can be scraped off, typically in immunocompromised patients 2

Clinical Features Suggesting GABHS Pharyngitis

Key features that increase probability of streptococcal infection include: 1

• Sudden onset sore throat with fever >38°C (100.4°F)
• Tonsillopharyngeal exudate (white or yellow patches)
• Tender enlarged anterior cervical lymph nodes
• Absence of cough, coryza, conjunctivitis, or hoarseness
• Patient age 5-15 years (peak incidence)
• Winter/early spring presentation in temperate climates

Features suggesting viral etiology rather than GABHS: 1

• Presence of cough, hoarseness, or rhinorrhea
• Conjunctivitis
• Anterior stomatitis or discrete ulcerative lesions
• Viral exanthem
• Diarrhea

Diagnostic Approach

Do not rely on clinical diagnosis alone—bacteriologic confirmation is essential before prescribing antibiotics unless clinical features confidently exclude streptococcal infection. 1

Modified Centor Score for Risk Stratification 1, 3

Calculate points based on:

• Temperature ≥38°C: +1 point
• Absence of cough: +1 point
• Tender anterior cervical adenopathy: +1 point
• Tonsillar swelling/exudate: +1 point
• Age <15 years: +1 point
• Age ≥45 years: -1 point

Management based on score: 1

• Score 0-1: Neither antibiotics nor testing required
• Score 2-3: Perform rapid antigen detection test (RADT) or throat culture; base antibiotic decision on results
• Score 4+: Consider empiric antibiotics or perform confirmatory testing

Laboratory Testing

• Throat culture remains the gold standard with 90-95% sensitivity when performed correctly 1
• Rapid antigen detection tests (RADT) have high specificity (>95%) but variable sensitivity 1
• In children and adolescents: Negative RADT should be confirmed with throat culture due to higher risk of rheumatic fever 1
• In adults: Negative RADT without backup culture is acceptable given lower disease prevalence and minimal rheumatic fever risk 1

Critical sampling technique: Firmly swab both tonsils and posterior pharynx, avoiding cheeks, gums, and teeth 1

Treatment for Confirmed GABHS Pharyngitis

First-Line Therapy (Non-Penicillin Allergic)

Amoxicillin 500 mg twice daily for 10 days is the preferred first-line treatment in adults. 4, 5

Alternative first-line options: 5, 6

• Penicillin V 500 mg twice daily (or 250 mg four times daily) for 10 days
• Benzathine penicillin G 1,200,000 units intramuscularly as single dose (for patients ≥27 kg)

The full 10-day course is essential to maximize pharyngeal eradication and prevent acute rheumatic fever—do not shorten the duration. 4, 5

Penicillin-Allergic Patients

For non-anaphylactic/delayed reactions: 4, 5

• First-generation cephalosporins (cross-reactivity risk only 0.1%)
• Cephalexin 500 mg twice daily for 10 days

For immediate/anaphylactic reactions: 4, 5

• Clindamycin 300 mg three times daily for 10 days (preferred—only 1% resistance in U.S.)
• Azithromycin 500 mg once daily for 5 days (acceptable but increasing resistance of 5-8% in U.S.)

Critical Pitfalls to Avoid

• Never use cephalosporins in patients with immediate/anaphylactic penicillin reactions—the 10% cross-reactivity risk is dangerous 5, 7
• Avoid macrolides (azithromycin, clarithromycin) as first-line when penicillin/amoxicillin can be used due to increasing resistance 4, 8
• Do not prescribe broad-spectrum cephalosporins (cefdinir, cefpodoxime) when narrow-spectrum options are effective 4
• Do not shorten treatment courses below 10 days (except azithromycin's 5-day regimen)—this increases treatment failure and rheumatic fever risk 5

Treatment for Groups C and G Streptococcal Pharyngitis

Use identical antibiotic regimens as for GABHS pharyngitis, as clinical approach and antimicrobial susceptibility patterns are similar. 7

Adjunctive Symptomatic Management

• Acetaminophen or NSAIDs (ibuprofen) for fever and throat pain 4, 5
• Corticosteroids are NOT recommended as adjunctive therapy 4, 5
• Aspirin must be avoided in children due to Reye syndrome risk 5

Special Considerations

When NOT to Test or Treat

• Children <3 years old: GABHS pharyngitis and acute rheumatic fever are both rare in this age group; exudative pharyngitis is uncommon 1
• Asymptomatic household contacts: Do not test or treat routinely—penicillin prophylaxis has not been shown to reduce subsequent infection rates 1, 5

Follow-Up

• Routine post-treatment cultures are NOT recommended for asymptomatic patients who completed therapy 5
• Re-evaluate patients with: 5
  • Worsening symptoms after 48-72 hours of appropriate antibiotics
  • Symptoms persisting >5 days after treatment initiation

Infectious Mononucleosis Considerations

When EBV is suspected (generalized lymphadenopathy, splenomegaly, severe fatigue): 1

• Avoid amoxicillin/ampicillin—these cause a characteristic maculopapular rash in 80-100% of patients with EBV
• Consider heterophile antibody testing (Monospot) or EBV-specific serology
• Treatment is supportive only; antibiotics are not indicated

Candidal Pharyngitis

For suspected oral/pharyngeal candidiasis (white plaques that scrape off, immunocompromised host): 2

• Fluconazole 200 mg on day 1, then 100 mg daily for minimum 2 weeks
• Treat underlying immunosuppression when possible