Centor Criteria for Strep Throat
The Centor criteria consist of four clinical features—fever by history, tonsillar exudates, tender anterior cervical adenopathy, and absence of cough—that help stratify the probability of group A streptococcal pharyngitis and guide testing and treatment decisions. 1
The Four Components
Each criterion receives one point for a maximum score of 4: 2, 3
- Fever by history (temperature >38°C or 100.4°F)
- Tonsillar exudates (white or yellow patches on tonsils)
- Tender anterior cervical lymphadenopathy (painful swollen nodes in front of neck)
- Absence of cough (cough suggests viral etiology)
Risk Stratification by Score
The score directly correlates with probability of streptococcal infection: 2, 3
- Score 0: 1-2.5% probability of group A strep
- Score 1: 5-10% probability
- Score 2: 11-17% probability
- Score 3: 28-35% probability
- Score 4: 51-53% probability
Clinical Decision Algorithm
For scores 0-2 (low probability): Do not perform testing or initiate antibiotics. 1 Provide symptomatic management with ibuprofen or acetaminophen for pain and fever relief. 1, 3
For scores 3-4 (higher probability): Perform a rapid antigen detection test (RADT). 1 If the RADT is positive, treat with penicillin V for 10 days. 2, 3 If RADT is performed, throat culture is not necessary after a negative result in both children and adults. 1
Recommended Antibiotic Treatment
When antibiotics are indicated based on positive testing: 1
- First-line: Penicillin V for 10 days or single intramuscular injection of benzathine penicillin 4
- Alternative first-line: Amoxicillin (equally effective and more palatable) 4
- Penicillin allergy: First-generation cephalosporins, clindamycin, or macrolide antibiotics 4, 5
Important Clinical Caveats
The Centor criteria have low positive predictive value—even with a score of 4, only about half of patients actually have group A strep, highlighting the need for confirmatory testing rather than empiric treatment. 1, 3
Utility is lower in children than adults because of different clinical presentations of sore throat in the first years of life, particularly in children under 5 years old. 1, 6
Modest benefits of antibiotics must be weighed against harms: Antibiotics shorten symptom duration by only 1-2 days, with a number needed to treat of 6 after 3 days and 21 after 1 week. 1 Side effects, impact on microbiota, increased antibiotic resistance, and costs must be considered. 2, 3
Red Flag Symptoms Requiring Urgent Evaluation
Patients with unusually severe signs warrant evaluation for rare but serious infections: 1
- Difficulty swallowing with drooling (suggests impending airway obstruction)
- Neck tenderness or swelling (may indicate deep space infection or Lemierre syndrome)
- Muffled voice (suggests peritonsillar or parapharyngeal abscess)
- Trismus (suggests peritonsillar abscess)
Be vigilant for Lemierre syndrome in adolescents and young adults with severe pharyngitis, as Fusobacterium necrophorum is implicated in 10-20% of endemic pharyngitis cases in this age group. 1, 7
Testing Technique Matters
Both the posterior pharyngeal wall and both tonsils must be swabbed to optimize test accuracy—improper swabbing technique can reduce sensitivity and lead to false-negative results. 2, 3
Viral Features That Argue Against Testing
Patients with sore throat plus any of these features are more likely to have viral illness and should not have further testing: 1
- Cough
- Nasal congestion
- Conjunctivitis
- Hoarseness
- Diarrhea
- Oropharyngeal lesions (ulcers or vesicles)