From the Guidelines
Adults should be tested for strep throat if they have a Centor score of 3-4, as these criteria help identify patients with a higher likelihood of group A streptococcal infection. The Centor criteria include:
- Fever
- Absence of cough
- Swollen/tender anterior cervical lymph nodes
- Tonsillar exudates Each present criterion counts as one point. According to the European Society for Clinical Microbiology and Infectious Diseases guideline 1, in patients with high likelihood of streptococcal infections (e.g. 3–4 Centor criteria) physicians can consider the use of rapid antigen test (RAT). If antibiotics are indicated, penicillin V, twice or three times daily for 10 days is recommended 1. It's essential to weigh the modest benefits of antibiotics against side effects, the effect of antibiotics on microbiota, increased antibacterial resistance, medicalisation and costs, especially in patients with less severe presentation of sore throat (0–2 Centor criteria) 1. The prevention of suppurative complications is not a specific indication for antibiotic therapy in sore throat 1. In real-life clinical practice, it's crucial to consider these factors to reduce unnecessary antibiotic use while ensuring appropriate treatment for bacterial infections.
From the Research
Centor Score Criteria for Adults with Strep
The Centor score is a clinical prediction rule used to estimate the probability of group A β-haemolytic streptococcal (GABHS) pharyngitis in adults. The criteria for the Centor score include:
- Fever
- Tonsillar exudate
- Cervical lymphadenitis
- Absence of cough
Calculation of Centor Score
The Centor score is calculated by assigning one point for each of the above criteria that is present. The score ranges from 0 to 4, with higher scores indicating a higher probability of GABHS pharyngitis 2, 3.
Management of Adults with Sore Throat based on Centor Score
The management of adults with sore throat based on the Centor score is as follows:
- Centor score of 1: No testing and no treatment is preferred 2
- Centor score of 2: Two strategies, culture and treat if positive and rapid strep with culture of negative results, are equally preferable 2
- Centor score of 3 or 4: Rapid strep with culture of negative results is the best management strategy 2
Diagnostic Accuracy of Centor Score
The Centor score has reasonable specificity (0.82,95% CI 0.72 to 0.88) and a post-test probability of 12% to 40% based on a prior prevalence of 5% to 20% 3. The score is a well-calibrated clinical prediction rule for estimating the probability of GABHS pharyngitis 3.
Limitations of Centor Score
Individual signs and symptoms are not powerful enough to discriminate GABHS pharyngitis from other types of sore throat 3. The Centor score should be used with caution in low prevalence settings of GABHS pharyngitis such as primary care 3.