Should a 31-year-old female (F) patient with a Centor score of 3, indicating moderate to high risk of streptococcal pharyngitis, be started on antibiotics?

Should You Start Antibiotics for a 31-Year-Old Female with Centor Score 3?

Yes, you should perform testing (rapid antigen detection test or throat culture) for group A streptococcus, and only start antibiotics if the test is positive. 1

Testing is Required Before Treatment

With a Centor score of 3, this patient falls into the intermediate-risk category where testing is mandatory before making treatment decisions:

• Patients with 3 or 4 Centor criteria should undergo rapid antigen detection test (RADT) or throat culture before initiating antibiotics 1
• Do not treat empirically at this score—testing is essential to confirm group A streptococcal infection 1
• In adults, a positive RADT alone is sufficient to diagnose and does not require backup culture confirmation due to high specificity 1
• Negative RADT results in adults do not routinely require backup throat culture, unlike in children, because the incidence of GAS pharyngitis and risk of acute rheumatic fever is lower in adults 1

If Testing is Positive: First-Line Antibiotic Treatment

Penicillin V or amoxicillin for 10 days is the treatment of choice for confirmed group A streptococcal pharyngitis 1, 2:

• Penicillin V 500 mg orally twice daily for 10 days or amoxicillin 500 mg orally twice daily for 10 days 1, 2
• These narrow-spectrum agents are preferred due to proven efficacy, safety, low cost, and no documented resistance 1, 2, 3
• The full 10-day course is mandatory to achieve maximal pharyngeal eradication and prevent acute rheumatic fever, even if symptoms improve earlier 1, 2, 4

Alternative Regimens for Penicillin Allergy

If the patient has a penicillin allergy:

• For non-anaphylactic allergy: First-generation cephalosporin (cephalexin 500 mg orally twice daily for 10 days) 1, 2, 5
• For anaphylactic allergy: Clindamycin 300 mg orally three times daily for 10 days, or azithromycin 500 mg on day 1, then 250 mg daily for days 2-5 1, 2, 6
• Note that azithromycin resistance varies geographically, and susceptibility testing should be performed when using macrolides 6, 7

Clinical Benefits of Treatment

When GAS pharyngitis is confirmed and treated appropriately:

• Antibiotics shorten symptom duration by 1-2 days 1
• Treatment prevents acute rheumatic fever, reduces transmission to close contacts, and may prevent suppurative complications 3
• The number needed to treat to reduce symptoms is 6 after 3 days and 21 after 1 week 1

Common Pitfalls to Avoid

• Do not treat without testing at Centor score 3—over 60% of adults with sore throat receive unnecessary antibiotics, but most pharyngitis is viral 1
• Do not use broad-spectrum antibiotics like cefuroxime, as they increase resistance without additional benefit 2
• Do not shorten treatment duration below 10 days (except azithromycin 5-day regimen), as this increases therapeutic failure and rheumatic fever risk 2
• Ensure the patient completes the full course even when feeling better—stopping early promotes resistance and decreases effectiveness 3, 4

Adjunctive Symptomatic Treatment

• Acetaminophen or ibuprofen for moderate to severe symptoms or high fever 1, 2
• Avoid aspirin in younger patients due to Reye syndrome risk 1, 2
• Corticosteroids are not recommended 1, 2