What are the Centor criteria for diagnosing streptococcal pharyngitis?

The Centor Criteria for Diagnosing Streptococcal Pharyngitis

The Centor criteria are a clinical scoring system used to identify patients with a higher likelihood of group A streptococcal pharyngitis, consisting of four criteria: fever by history, tonsillar exudates, tender anterior cervical adenopathy, and absence of cough. 1

Components of the Centor Criteria

The modified Centor criteria include the following four clinical features:

• Fever by history (temperature >38°C or 100.4°F) 1
• Tonsillar exudates (white or yellow patches on tonsils) 1
• Tender anterior cervical adenopathy (swollen, painful lymph nodes in the front of the neck) 1
• Absence of cough 1, 2

Clinical Application and Scoring

The Centor criteria help clinicians determine the likelihood of streptococcal pharyngitis and guide testing and treatment decisions:

• Score 0-1: Low risk of streptococcal infection (≤10%). No testing or antibiotics recommended 2, 1
• Score 2-3: Intermediate risk. Rapid antigen detection test (RADT) recommended 1, 2
• Score 4: High risk of streptococcal infection (>50%). Consider empiric antibiotic therapy or perform RADT 2, 3

Evidence Supporting the Centor Criteria

The Centor criteria have been validated in multiple studies and are recommended by major guidelines:

• The Infectious Diseases Society of America (IDSA) recognizes the Centor criteria as a useful tool to identify patients with low probability of group A streptococcal pharyngitis 1
• Clinical scoring systems like the Centor criteria can help target antibiotic therapy to patients most likely to have streptococcal infection 1, 2
• The sensitivity of rapid antigen detection tests increases with higher Centor scores, showing a stepwise increase from patients with one criterion to those with all four criteria 4

Limitations and Considerations

• The Centor criteria have lower utility in children compared to adults due to differences in clinical presentation in early years of life 1
• The criteria have a low positive predictive value when used alone, which is why they are often combined with laboratory testing 1
• The criteria do not differentiate between group A streptococcus and other causes of pharyngitis, such as viral infections 5

Integration with Testing Strategies

For optimal diagnosis of streptococcal pharyngitis:

• Patients with fewer than 3 Centor criteria do not need testing 1
• Patients with 2-4 Centor criteria should undergo rapid antigen detection testing 2, 3
• Throat culture (the gold standard) is generally not necessary for routine diagnosis or after a negative rapid test with >80% sensitivity 2, 5

Common Pitfalls to Avoid

• Overreliance on clinical features alone without considering the Centor score can lead to unnecessary antibiotic prescriptions 4
• Failure to recognize that cough, coryza (runny nose), conjunctivitis, and diarrhea suggest viral rather than streptococcal etiology 5, 6
• Not considering rare but serious throat infections in patients with severe symptoms despite low Centor scores 1

The Centor criteria remain a valuable clinical tool for the initial assessment of patients with suspected streptococcal pharyngitis, helping to reduce unnecessary testing and antibiotic use while identifying those most likely to benefit from treatment.