Complete treatment for acute pharyngitis
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acute pharyngitis diagnosis etiology streptococcal Centor score
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Here is a comprehensive overview of acute pharyngitis:
Acute Pharyngitis: Complete Treatment Guide
Etiology
| Pathogen | Notes |
|---|---|
| Viral (most common, ~80–90%) | Rhinovirus, adenovirus, EBV, influenza, parainfluenza, HSV, enterovirus |
| Group A Streptococcus (GAS) | Most important bacterial cause; ~5–15% adults, up to 30% in children |
| Group C/G Streptococcus | Less common, milder disease |
| Fusobacterium necrophorum | Adolescents/young adults; risk of Lemierre syndrome |
| Mycoplasma pneumoniae | Atypical; consider in persistent cases |
| Neisseria gonorrhoeae | Sexually transmitted; consider in at-risk patients |
Clinical Features
Viral Pharyngitis
- Gradual onset, mild-to-moderate sore throat
- Rhinorrhea, cough, hoarseness, conjunctivitis ("red flag" features against GAS)
- Low-grade fever; no significant lymphadenopathy
GAS (Streptococcal) Pharyngitis
- Sudden onset severe sore throat
- High fever (>38.3°C), chills
- Tonsillar exudates, erythema
- Tender anterior cervical lymphadenopathy
- Absence of cough, rhinorrhea, or hoarseness
- Petechiae on palate, scarlatiniform rash (scarlet fever)
Diagnosis: Centor Criteria
Each criterion scores 1 point:
| Criterion | Points |
|---|---|
| History of fever | +1 |
| Absence of cough | +1 |
| Tender anterior cervical lymphadenopathy | +1 |
| Tonsillar exudate or swelling | +1 |
Probability of GAS by score (Harrison's, p. 1071):
| Score | GAS Probability |
|---|---|
| 0 | ~2% |
| 1 | ~5–10% |
| 2 | ~11–17% |
| 3 | ~28–35% |
| 4 | ~41–56% |
Modified McIsaac Criteria adds 1 point for age 3–14 and subtracts 1 point for age ≥45.
Testing Strategy
| Score | Action |
|---|---|
| 0–1 | No testing; no antibiotics (viral etiology likely) |
| 2–3 | Rapid antigen detection test (RADT); treat if positive |
| 4 | Empirical antibiotic treatment OR RADT to confirm |
- RADT: Specificity ~98%, sensitivity ~70–90%. If negative and suspicion remains (score ≥3), confirm with throat culture (gold standard; sensitivity ~90–95%, results in 24–48h).
- Throat culture is preferred in children to prevent rheumatic fever.
Treatment
1. Symptomatic / Supportive (All Patients)
| Agent | Dose | Purpose |
|---|---|---|
| Paracetamol (Acetaminophen) | 500–1000 mg PO q4–6h PRN | Analgesia, antipyresis |
| Ibuprofen | 400–600 mg PO q6–8h with food | Analgesia, anti-inflammatory |
| Aspirin (adults only) | 325–650 mg PO q4–6h | Analgesia, antipyresis |
| Benzocaine lozenges / sprays | As directed | Topical analgesia |
| Lidocaine mouthwash (viscous) | Gargle q3h | Topical analgesia |
| Saline gargles | Warm saline several times/day | Symptom relief |
| Adequate hydration | — | Supportive |
- Corticosteroids: A single dose of dexamethasone 10 mg IM/PO or betamethasone 8 mg IM significantly reduces pain onset and duration. Consider in moderate-to-severe pain, especially when antibiotics are also being given. Not routinely recommended without antibiotic co-prescription.
2. Antibiotic Treatment (GAS-Confirmed or High Suspicion)
Benefits: Shorten duration of sore throat by 1–2 days, prevent acute rheumatic fever (ARF), reduce peritonsillar abscess risk, limit GAS transmission. (Appropriate Antibiotic Use Guidelines, p. 6)
Note: Antibiotics do NOT prevent acute post-streptococcal glomerulonephritis (APSGN).
First-Line Therapy
| Drug | Adult Dose | Duration | Notes |
|---|---|---|---|
| Penicillin V (Phenoxymethylpenicillin) | 500 mg PO BID–TID | 10 days | Drug of choice; narrow spectrum |
| Amoxicillin | 500 mg PO BID or 1g PO once daily | 10 days | Equally effective; better palatability (preferred in children) |
| Benzathine Penicillin G | 1.2 million units IM single dose | Once | If adherence is a concern; ensures complete course |
Penicillin-Allergic Patients
| Drug | Adult Dose | Duration | Notes |
|---|---|---|---|
| Azithromycin | 500 mg PO Day 1, then 250 mg Days 2–5 | 5 days | Use only if GAS susceptibility confirmed; resistance ~5–10% |
| Clarithromycin | 250 mg PO BID | 10 days | Alternative macrolide |
| Cephalexin (1st-gen cephalosporin) | 500 mg PO BID | 10 days | If non-anaphylactic allergy to penicillin |
| Clindamycin | 300 mg PO TID | 10 days | For severe/anaphylactic penicillin allergy |
GAS remains universally sensitive to penicillin — no resistance reported.
3. Treatment of Specific Causes
| Etiology | Treatment |
|---|---|
| Viral pharyngitis | Supportive only; no antibiotics |
| EBV (Infectious Mononucleosis) | Supportive; avoid ampicillin/amoxicillin (rash); avoid contact sports (splenomegaly risk) |
| HSV pharyngitis | Acyclovir 400 mg TID × 7–10 days (immunocompromised or severe disease) |
| Gonorrheal pharyngitis | Ceftriaxone 500 mg IM single dose |
| Fusobacterium / Lemierre | IV ampicillin-sulbactam or metronidazole + beta-lactam; consider anticoagulation |
4. Special Populations
| Group | Consideration |
|---|---|
| Children | Throat culture preferred; full 10-day penicillin course mandatory to prevent ARF |
| Adults (score 0–1) | No testing, no antibiotics; reassure and give symptom relief |
| Recurrent GAS (≥6/year) | Consider tonsillectomy in children; NOT recommended in adults (Guidelines, p. 6) |
| Chronic GAS carriers | Antibiotics not indicated; no risk of spread or complications |
| Pregnancy | Avoid fluoroquinolones and tetracyclines; Penicillin V or amoxicillin is safe |
| Immunocompromised | Lower threshold for treatment; consider broader coverage |
Complications (If Untreated GAS)
| Complication | Notes |
|---|---|
| Peritonsillar abscess | Unilateral throat pain, uvular deviation, "hot potato" voice; requires drainage |
| Retropharyngeal / parapharyngeal abscess | Severe; requires CT and surgical drainage |
| Acute Rheumatic Fever (ARF) | More common in children; prevented by full antibiotic course |
| Post-streptococcal glomerulonephritis | NOT prevented by antibiotics |
| Lemierre Syndrome | Septic jugular vein thrombosis from F. necrophorum; rare but life-threatening |
| Scarlet fever | GAS toxin-mediated; treat with penicillin |
| Otitis media / sinusitis | Contiguous spread |
Red Flags Requiring Urgent Evaluation
- Stridor or respiratory distress → suspect epiglottitis or abscess
- "Hot potato" voice, uvular deviation → peritonsillar abscess
- Drooling, inability to swallow → epiglottitis (do not examine oropharynx)
- Neck stiffness, severe trismus → retropharyngeal abscess or Ludwig's angina
- Unilateral neck swelling, spiking fever → Lemierre syndrome
Summary Algorithm
Sore throat → Centor/McIsaac Score
↓
Score 0–1: Symptomatic treatment only
Score 2–3: RADT → Positive: Antibiotics | Negative: Culture if high risk
Score 4: Empirical Antibiotics (or RADT to confirm)
↓
GAS confirmed → Penicillin V 500 mg BID × 10 days (1st line)
↓
Penicillin allergy → Cephalexin / Clindamycin / Azithromycin
↓
Supportive: NSAIDs, analgesics, hydration ± single-dose dexamethasone
Sources: Harrison's Principles of Internal Medicine, 21st Ed. (p. 1071); Appropriate Antibiotic Use for Acute Respiratory Tract Infection in Adults (p. 6).
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