Overview
Acute Pharyngitis
Quick Reference
Critical Alerts
- Peritonsillar abscess is a complication: "Hot potato" voice, uvular deviation
- Epiglottitis is life-threatening: Stridor, drooling, tripod position
- Centor/McIsaac criteria guide testing and treatment: Not all sore throats need antibiotics
- Treat GAS to prevent rheumatic fever: 10 days of penicillin
- Most pharyngitis is viral: Antibiotics not needed for most cases
- Mononucleosis can mimic GAS: Avoid amoxicillin (causes rash)
Centor Criteria (Modified McIsaac)
| Criterion | Points |
|---|---|
| Fever >8°C (100.4°F) | +1 |
| Absence of cough | +1 |
| Tender anterior cervical lymphadenopathy | +1 |
| Tonsillar exudates or swelling | +1 |
| Age 3-14 years | +1 |
| Age 15-44 years | 0 |
| Age ≥45 years | -1 |
Score Interpretation:
| Score | Action |
|---|---|
| 0-1 | No testing, no antibiotics |
| 2-3 | Rapid strep test; treat if positive |
| 4-5 | Consider empiric treatment; test to confirm |
Emergency Treatments
| Condition | Treatment |
|---|---|
| Suspected GAS pharyngitis | Penicillin VK 500mg BID-TID × 10 days OR Amoxicillin 1g daily × 10 days |
| Penicillin allergy | Azithromycin 500mg × 1, then 250mg daily × 4 days |
| Viral pharyngitis | Supportive care (analgesics, fluids) |
| Peritonsillar abscess | Needle aspiration or I&D + antibiotics |
Definition
Overview
Acute pharyngitis is inflammation of the pharynx causing sore throat. Most cases are viral and self-limited. Group A Streptococcus (GAS) is the most important bacterial cause, responsible for about 5-15% of adult and 15-30% of pediatric cases. Identifying GAS is important to prevent suppurative complications (peritonsillar abscess) and non-suppurative complications (rheumatic fever).
Classification
By Etiology:
| Type | Causes |
|---|---|
| Viral (most common) | Rhinovirus, adenovirus, EBV (mononucleosis), HSV, influenza, COVID-19 |
| Bacterial | Group A Streptococcus (GAS), Group C/G Strep, Fusobacterium (Lemierre) |
| Other | Mycoplasma, Chlamydia, fungal (immunocompromised) |
Epidemiology
- Very common: Millions of cases/year
- Viral predominates: 60-70% of cases
- GAS: 5-15% of adult; 15-30% of pediatric cases
- Peak season: Winter and early spring
Etiology
Common Pathogens:
| Type | Organisms |
|---|---|
| Viral | Rhinovirus, coronavirus, adenovirus, EBV, influenza, parainfluenza, HSV |
| Bacterial | GAS (S. pyogenes), Group C/G Strep, Arcanobacterium haemolyticum, Fusobacterium |
Risk Factors for GAS:
- School-age children (5-15 years)
- Close contact with infected person
- Winter/spring season
Pathophysiology
Mechanism
Viral:
- Direct viral invasion of pharyngeal mucosa
- Inflammatory response
- Self-limited (resolves in 5-7 days)
GAS:
- Adherence to pharyngeal epithelium
- Toxin production
- Local inflammation
- Risk of immune-mediated complications (ARF, PSGN)
Complications of GAS
| Suppurative | Non-Suppurative |
|---|---|
| Peritonsillar abscess | Acute rheumatic fever |
| Retropharyngeal abscess | Post-streptococcal glomerulonephritis |
| Cervical lymphadenitis | Reactive arthritis |
| Otitis media | PANDAS |
| Sinusitis |
Clinical Presentation
Symptoms
| Finding | GAS Suggestive | Viral Suggestive |
|---|---|---|
| Sore throat | Sudden onset, severe | Gradual onset |
| Fever | High (>8°C) | Low-grade or absent |
| Cough | Absent | Present |
| Rhinorrhea | Absent | Present |
| Tonsillar exudates | Present | Absent (or EBV) |
| Cervical lymphadenopathy | Tender, anterior | Less prominent |
| Conjunctivitis | Absent | May be present |
| Rash | Scarlatiniform (sandpaper) | Absent |
History
Key Questions:
Physical Examination
| Finding | Significance |
|---|---|
| Pharyngeal erythema | Non-specific |
| Tonsillar exudates | GAS, EBV, adenovirus |
| Tender anterior cervical lymph nodes | GAS |
| Palatal petechiae | GAS (specific but insensitive) |
| Scarlatiniform rash | GAS (scarlet fever) |
| Strawberry tongue | GAS |
| Uvular deviation, trismus | Peritonsillar abscess |
| Hepatosplenomegaly | Mononucleosis |
Duration and severity of sore throat
Common presentation.
Fever, chills
Common presentation.
Cough, rhinorrhea (suggests viral)
Common presentation.
Exposure to strep pharyngitis
Common presentation.
History of rheumatic fever
Common presentation.
Recent antibiotic use
Common presentation.
Immunocompromise
Common presentation.
Difficulty swallowing or breathing (red flag)
Common presentation.
Red Flags
Life-Threatening Conditions
| Finding | Concern | Action |
|---|---|---|
| Stridor, drooling, tripod | Epiglottitis | Airway management, do NOT examine throat if unstable |
| Uvular deviation, "hot potato" voice | Peritonsillar abscess | Needle aspiration, ENT |
| Severe trismus | Deep space infection | CT, ENT |
| Neck swelling, septic appearance | Lemierre syndrome, retropharyngeal abscess | CT, IV antibiotics |
| Dyspnea, respiratory distress | Airway compromise | Emergent airway |
Differential Diagnosis
Other Causes of Sore Throat
| Diagnosis | Features |
|---|---|
| Mononucleosis (EBV) | Fatigue, splenomegaly, atypical lymphocytes |
| Peritonsillar abscess | Uvular deviation, trismus, "hot potato" voice |
| Epiglottitis | Stridor, drooling, tripod position |
| Retropharyngeal abscess | Neck stiffness, dysphagia |
| Oral thrush | White plaques, immunocompromise |
| HSV gingivostomatitis | Vesicles, ulcers |
| Diphtheria | Gray pseudomembrane (rare) |
| Lemierre syndrome | Septic thrombophlebitis of jugular vein |
| Kawasaki disease (children) | Fever > days, rash, strawberry tongue |
Diagnostic Approach
Clinical Scoring (Centor/McIsaac)
Use to guide testing:
| Score | Action |
|---|---|
| 0-1 | No test, no antibiotics |
| 2-3 | Rapid antigen detection test (RADT); treat if positive |
| 4-5 | RADT (or empiric treatment); confirm with culture if needed |
Rapid Antigen Detection Test (RADT)
| Feature | Details |
|---|---|
| Sensitivity | 70-90% |
| Specificity | 95-99% |
| Use | Rule in GAS if positive |
| Follow-up | Consider throat culture if RADT negative and high suspicion |
Throat Culture
| Feature | Details |
|---|---|
| Gold standard | For GAS diagnosis |
| Sensitivity | >0% |
| Turnaround | 24-48 hours |
| Use | Confirm negative RADT in children (AAP recommends) |
Other Testing (If Suspected)
| Test | Indication |
|---|---|
| Monospot (heterophile antibody) | EBV suspected |
| CBC | Atypical lymphocytes (EBV), leukocytosis |
| CT neck | Deep space infection, abscess |
| HIV testing | Risk factors, recurrent infections |
Treatment
Principles
- Determine likelihood of GAS: Use Centor/McIsaac criteria
- Test appropriately: RADT ± throat culture
- Treat GAS to prevent rheumatic fever: 10 days of penicillin
- Supportive care for viral pharyngitis: Analgesics, hydration
- Identify and manage complications: Peritonsillar abscess
GAS Pharyngitis Treatment
First-Line:
| Agent | Dose | Duration |
|---|---|---|
| Penicillin VK | 250 mg QID or 500 mg BID | 10 days |
| Amoxicillin | 50 mg/kg once daily (max 1g) or 25 mg/kg BID | 10 days |
| Benzathine penicillin G | 1.2 million units IM × 1 (adults); 600,000 units (children <27 kg) | Single dose |
Penicillin Allergy:
| Agent | Dose | Duration |
|---|---|---|
| Azithromycin | 500 mg day 1, then 250 mg days 2-5 | 5 days |
| Cephalexin (if non-anaphylactic allergy) | 500 mg BID | 10 days |
| Clarithromycin | 250 mg BID | 10 days |
Viral Pharyngitis (Supportive Care)
| Intervention | Details |
|---|---|
| Analgesics | Acetaminophen, ibuprofen |
| Throat lozenges | Symptomatic relief |
| Warm salt water gargles | Comfort |
| Hydration | Oral fluids |
| Humidified air | May help |
Mononucleosis (EBV)
- Supportive care: Rest, analgesics, hydration
- Avoid contact sports: Risk of splenic rupture
- Avoid amoxicillin/ampicillin: Causes rash in EBV
- Steroids: Consider only for severe airway edema
Peritonsillar Abscess
- Needle aspiration or I&D: Definitive
- Antibiotics: Ampicillin-sulbactam or clindamycin
- Pain control: Opioids if needed
- ENT consultation: For drainage or recurrence
Disposition
Discharge Criteria
- Able to swallow fluids
- Pain controlled
- No airway compromise
- Reliable follow-up
Admission Criteria
- Airway compromise
- Deep space infection
- Unable to tolerate oral intake
- Severe dehydration
- Immunocompromised with severe illness
Referral
| Indication | Referral |
|---|---|
| Peritonsillar abscess | ENT (urgent) |
| Recurrent GAS (≥7 episodes/year) | ENT for tonsillectomy consideration |
| Suspected deep space infection | ENT |
Follow-Up
| Situation | Follow-Up |
|---|---|
| GAS pharyngitis | Not required if improving |
| Mononucleosis | PCP in 1-2 weeks; avoid sports |
| Peritonsillar abscess (drained) | ENT in 1-2 weeks |
Patient Education
Condition Explanation
- "You have a throat infection. Most are caused by viruses and don't need antibiotics."
- "If you have strep throat, you need antibiotics to prevent complications."
- "Finish all your antibiotics even if you feel better."
Home Care
- Take pain relievers as directed
- Drink plenty of fluids
- Rest
- Gargle with warm salt water
- Use throat lozenges for comfort
Warning Signs to Return
- Difficulty breathing or swallowing
- Drooling or inability to swallow saliva
- Severe neck swelling
- Worsening symptoms after 48 hours on antibiotics
- Rash (especially after taking amoxicillin)
Special Populations
Children
- Higher GAS prevalence (15-30%)
- RADT ± throat culture recommended (AAP)
- Rheumatic fever prevention is key
- Avoid aspirin (Reye syndrome)
Adults
- Lower GAS prevalence (5-15%)
- Consider clinical criteria alone (some guidelines)
- Throat culture backup less commonly recommended
Immunocompromised
- Consider broader differential (fungal, atypical)
- Lower threshold for cultures and imaging
- Broader antibiotic coverage if bacterial suspected
Quality Metrics
Performance Indicators
| Metric | Target | Rationale |
|---|---|---|
| Centor/McIsaac criteria used | >0% | Guide testing |
| RADT for score ≥2 | >0% | Avoid unnecessary antibiotics |
| Penicillin as first-line for GAS | >0% | Guideline adherence |
| No antibiotics for viral pharyngitis | >0% | Antibiotic stewardship |
Documentation Requirements
- Centor/McIsaac score
- RADT result (if performed)
- Antibiotic prescribed and duration
- Red flag symptoms absent
- Follow-up plan
Key Clinical Pearls
Diagnostic Pearls
- Centor/McIsaac guides testing: Not all sore throats need RADT
- Cough suggests viral: Less likely GAS
- Exudates can occur in viral: EBV, adenovirus
- Palatal petechiae are specific for GAS: But insensitive
- Monospot for EBV: Avoid amoxicillin
- RADT positive = Treat: RADT negative + high suspicion = Consider culture
Treatment Pearls
- Penicillin is first-line for GAS: 10(days
- Amoxicillin is acceptable alternative: Once daily convenient
- Azithromycin for penicillin allergy: 5 days
- Viral = Supportive only: No antibiotics
- EBV + Amoxicillin = Rash: Avoid this combination
- Complete full course: Prevents rheumatic fever
Disposition Pearls
- Most can be discharged: With or without antibiotics
- Peritonsillar abscess needs drainage: ENT, needle aspiration
- Airway compromise = Emergent: Epiglottitis, deep space infection
- Recurrent GAS → ENT referral: Consider tonsillectomy
References
- Shulman ST, et al. Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis. Clin Infect Dis. 2012;55(10):e86-e102.
- Choby BA. Diagnosis and treatment of streptococcal pharyngitis. Am Fam Physician. 2009;79(5):383-390.
- Wessels MR. Streptococcal Pharyngitis. N Engl J Med. 2011;364(7):648-655.
- Fine AM, et al. Large-scale validation of the Centor and McIsaac scores to predict group A streptococcal pharyngitis. Arch Intern Med. 2012;172(11):847-852.
- McIsaac WJ, et al. Empirical validation of guidelines for the management of pharyngitis in children and adults. JAMA. 2004;291(13):1587-1595.
- IDSA. Practice guidelines for the diagnosis and management of group A streptococcal pharyngitis. 2012.
- AAP. Red Book: 2021-2024 Report of the Committee on Infectious Diseases.
- UpToDate. Evaluation and management of pharyngitis in adults. 2024.