CENTOR
Strep Pharyngitis Probability (Centor / McIsaac)
1 point each. 0-1 no testing; 2-3 RADT; 4-5 treat or RADT.
Clinicians lean on this acronym when a sore throat walks in and the question is rapid strep, treat empirically, or reassure. Centor scores one point each for tonsillar exudate, tender anterior cervical nodes, fever over 100.4 F, and absence of cough; McIsaac adds an age modifier (+1 for ages 3-14, 0 for 15-44, -1 for 45+). Score 0-1 needs no testing; 2-3 gets a rapid antigen test; 4-5 supports empiric treatment or RADT depending on local practice. The AANP exam uses Centor to test antimicrobial stewardship — a 50-year-old with a cough and a sore throat is not a strep patient, no matter how dramatic the pharynx looks.
- CCough absentA cough argues AGAINST strep — viral is more likely.
- EExudate (tonsillar)White patches on tonsils.
- NNodes (tender anterior cervical)Painful adenopathy, not just palpable.
- TTemperature >38°C (100.4°F)Documented fever, not subjective.
- ORAge modifier (McIsaac)+1 if age 3-14; 0 if 15-44; -1 if ≥45. The McIsaac addition sharpens the score at the age extremes.
Clinical Context
Decides who gets a rapid strep test (RADT) vs. empiric antibiotics vs. no workup in acute pharyngitis. Score 0-1: no test, no treat (viral). Score 2-3: RADT — treat if positive. Score 4-5: treat empirically or RADT.
IDSA guidelines prefer RADT for any suspected strep ≥3 years old (Centor alone overtreats). Treatment is penicillin or amoxicillin × 10 days; azithromycin for PCN-allergic. Mono mimics strep — check a monospot in adolescents with posterior cervical nodes, splenomegaly, or lymphocytosis before prescribing amoxicillin (can cause rash).
AANP stem: "25-year-old with sore throat, fever 38.5°C, tonsillar exudate, tender anterior cervical nodes, no cough" — that's Centor 4. Trap: amoxicillin in undiagnosed mono → diffuse morbilliform rash.
Related Mnemonics
- PERRLA — Normal Pupillary Exam
Sources
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