Centor Criteria for Streptococcal Pharyngitis
The Four Clinical Criteria
The Centor score consists of four equally-weighted clinical features, each worth one point: fever by history, tonsillar exudates, tender anterior cervical lymphadenopathy, and absence of cough. 1, 2
- Each criterion receives one point for a maximum score of 4 2
- The score directly correlates with probability of Group A streptococcal (GAS) infection 1, 2
Risk Stratification by Score
The probability of GAS pharyngitis increases with higher scores 3:
- Score 0: 2.5-8% probability 1, 3
- Score 1: 5-12% probability 1, 3
- Score 2: 11-23% probability 1, 3
- Score 3: 28-38% probability 1, 3
- Score 4: 51-57% probability 1, 3
Clinical Management Algorithm
For Scores 0-2 (Low Probability)
Do not test and do not treat with antibiotics—provide symptomatic management only. 1, 2
- Use ibuprofen or acetaminophen for pain relief 4, 2
- Avoid aspirin in children 4
- These patients have low probability of GAS and do not warrant testing 1
For Scores 3-4 (Higher Probability)
Perform a rapid antigen detection test (RADT) and treat only if positive. 4, 1, 2
- Even with a score of 4, only about half actually have GAS pharyngitis, so confirmatory testing is essential rather than empiric treatment 2
- Both posterior pharyngeal wall and both tonsils must be swabbed to optimize test accuracy 1, 2
- Improper swabbing technique reduces sensitivity and leads to false-negative results 1, 2
Testing Considerations
- In adults: Negative RADTs do not require backup throat culture due to low incidence of GAS and exceptionally low risk of acute rheumatic fever 4
- In children and adolescents: Negative RADTs should be backed up by throat culture 4
- Positive RADTs do not require backup culture due to high specificity (≥95%) 4, 1
Recommended Antibiotic Treatment
When treatment is indicated based on positive testing, penicillin or amoxicillin for 10 days is first-line therapy. 4
- Penicillin V 250-500mg twice or three times daily for 10 days 5, 2
- These are preferred due to narrow spectrum, low adverse reactions, and modest cost 4
For Penicillin-Allergic Patients
Treatment options include 4:
- First-generation cephalosporin for 10 days (if not anaphylactically sensitive)
- Clindamycin for 10 days
- Clarithromycin for 10 days
- Azithromycin for 5 days
Important Clinical Caveats
Limitations of the Score
- The Centor score has low positive predictive value—even high scores do not confirm GAS infection with certainty 1, 6
- The score was validated only in adults, not children 2
- Utility appears lower in children due to different clinical presentations in early years of life 1
Antibiotic Benefits Are Modest
Weigh the modest benefits (1-2 days symptom reduction) against side effects, antibiotic resistance, microbiota impact, and costs. 1, 2
- Antibiotics primarily prevent suppurative and nonsuppurative complications, not just symptom relief 4
- Benefits must be balanced against risks in shared decision-making 1