What are the Centor criteria for diagnosing streptococcal pharyngitis?

Centor Criteria for Diagnosing Streptococcal Pharyngitis

The Centor criteria consist of four clinical features: fever by history, tonsillar exudates, tender anterior cervical adenopathy, and absence of cough, which help identify patients with higher likelihood of group A streptococcal pharyngitis. 1

Components of the Centor Criteria

The four components of the Centor clinical scoring system are:

• Fever by history (temperature >38°C/100.4°F) 1
• Tonsillar exudates (pus on tonsils) 1
• Tender anterior cervical adenopathy (swollen, painful lymph nodes in front of neck) 1
• Absence of cough 1

Clinical Application and Interpretation

The Centor criteria help stratify patients based on their likelihood of streptococcal infection:

• Score 0-1: Very low risk of streptococcal infection; no testing or antibiotics recommended 1
• Score 2: Low risk of streptococcal infection; testing may be considered but is generally not necessary 1
• Score 3-4: Moderate to high risk of streptococcal infection; rapid antigen testing (RAT) should be considered 1, 2

Diagnostic Approach Based on Centor Score

• Patients with fewer than 3 Centor criteria do not need to be tested for group A streptococcus as they have a low probability of streptococcal pharyngitis 1, 2
• In patients with high likelihood of streptococcal infections (3-4 Centor criteria), physicians should consider using rapid antigen tests (RATs) 1, 2
• If RAT is performed, throat culture is not necessary after a negative RAT for the diagnosis of group A streptococci in both children and adults 1, 2

Limitations and Considerations

• The Centor criteria have a low positive predictive value for determining the presence of group A streptococcal infection 1
• The utility of Centor criteria appears lower in children than in adults because of different clinical presentation of sore throat in the first years of life 1
• Some studies suggest that the Centor score has a sensitivity of 50% and specificity of 97.6% for scores of 3, and 100% specificity for scores of 4 3
• Recent research suggests that adding palatal petechiae to the Centor criteria may improve diagnostic accuracy in children 4

Treatment Considerations

• Antibiotics should not be used in patients with less severe presentation (0-2 Centor criteria) 1, 2
• For patients with 3-4 Centor criteria, modest benefits of antibiotics (shortening symptoms by 1-2 days) should be weighed against side effects, impact on microbiota, increased antibiotic resistance, medicalization, and costs 1, 2
• If antibiotics are indicated based on Centor criteria and confirmatory testing, penicillin V for 10 days is the recommended first-line treatment 1, 2

Common Pitfalls

• Overreliance on Centor criteria alone without considering other clinical factors 1, 5
• Failing to recognize that most pharyngitis cases (>65%) are viral in origin, even with high Centor scores 2, 5
• Not considering other serious throat infections in patients with unusually severe symptoms (peritonsillar abscess, epiglottitis, Lemierre syndrome) 1, 2
• Automatically prescribing antibiotics for high Centor scores without confirmatory testing, contributing to antibiotic overuse 1