Evaluation and Management of Acute Pharyngitis
Who Should Be Tested for Group A Streptococcal (GAS) Pharyngitis
Testing should be reserved for patients with clinical features suggesting bacterial rather than viral infection, and should be avoided entirely in children under 3 years of age. 1
Do NOT test patients with:
- Cough, rhinorrhea, hoarseness, conjunctivitis, or oral ulcers—these strongly indicate viral etiology 1, 2
- Age < 3 years (except when an older sibling has confirmed GAS infection) 1, 2
DO test patients with:
- Sudden-onset sore throat 1
- Fever 1
- Tonsillar exudates 1
- Tender anterior cervical lymphadenopathy 1
- Absence of viral features 1
Common pitfall: White patches and exudates occur with both viral and bacterial infections; never prescribe antibiotics based on appearance alone without laboratory confirmation. 2
Diagnostic Testing Strategy
Adults
A negative rapid antigen detection test (RADT) alone is sufficient to rule out GAS pharyngitis—no backup throat culture is needed. 1, 2
- RADT specificity ≥95% (false positives are rare) 1, 2
- RADT sensitivity 80-90% 1, 2
- Adults have only 5-10% prevalence of GAS pharyngitis and extremely low risk of acute rheumatic fever, making the false-negative rate acceptable 2
Children and Adolescents (Ages 3-18)
A negative RADT must be confirmed with a backup throat culture before withholding antibiotics. 1, 2
- Children ages 5-15 have 20-30% prevalence of GAS pharyngitis 2
- RADT sensitivity of 80-90% means 10-20% of true infections are missed 1, 2
- Higher risk of acute rheumatic fever justifies the two-step approach 1, 2
- Treatment can be initiated within 9 days of symptom onset and still prevent acute rheumatic fever 2
Critical distinction: A positive throat culture obtained after a negative RADT confirms active infection and requires treatment. 2
Antibiotic Treatment for Confirmed GAS Pharyngitis
First-Line Therapy (10 days required)
Penicillin or amoxicillin for 10 days is the definitive first-line regimen based on narrow spectrum, proven efficacy, safety, and low cost. 1
| Agent | Pediatric Dose | Adult Dose | Duration |
|---|---|---|---|
| Penicillin V | 250 mg 2-3×/day (<27 kg) 500 mg 2-3×/day (≥27 kg) |
500 mg 2-3×/day | 10 days [1] |
| Amoxicillin | 50 mg/kg once daily (max 1 g) | 1 g once daily | 10 days [1] |
| Benzathine penicillin G (IM) | 600,000 U single dose (<27 kg) 1,200,000 U (≥27 kg) |
1,200,000 U single dose | Single dose [1] |
Use intramuscular benzathine penicillin G when adherence to oral therapy is questionable. 1
Penicillin-Allergic Patients
Non-anaphylactic allergy:
- First-generation cephalosporin (cephalexin or cefadroxil) for 10 days 1
Anaphylactic or immediate-type hypersensitivity:
- Clindamycin 7 mg/kg/dose 3×/day (max 300 mg/dose) for 10 days 1
- Azithromycin 12 mg/kg once daily (max 500 mg) for 5 days 1
- Clarithromycin 7.5 mg/kg/dose 2×/day (max 250 mg/dose) for 10 days 1
Important caveat: Macrolide resistance varies geographically (approximately 5-8% in the US); consider local resistance patterns when selecting alternatives. 2
Management When Testing Is Negative
Withhold antibiotics entirely and provide only symptomatic therapy—the vast majority of negative-test cases are viral and self-limited. 1, 2
Symptomatic Treatment
- Analgesics/antipyretics: Ibuprofen or acetaminophen for pain and fever relief 1, 2
- Avoid aspirin in children due to Reye syndrome risk 1
- Corticosteroids are NOT recommended 1
- Throat lozenges may provide comfort 2
Key quality indicator: Withholding or discontinuing antimicrobial therapy for patients with negative microbiological tests is a marker of appropriate care. 1
Follow-Up Testing and Carrier State
Routine Post-Treatment Testing Is NOT Recommended
Do not perform follow-up throat cultures or RADTs in asymptomatic patients who have completed appropriate antibiotic therapy. 1
- Positive post-treatment tests often reflect asymptomatic carrier state rather than treatment failure 1
- Up to 20% of school-aged children are asymptomatic GAS carriers during winter and spring 3
- Carriers are at low risk for complications and unlikely to spread infection 1
Special Circumstances Where Follow-Up Testing May Be Considered
- Personal history of acute rheumatic fever 1
- Outbreaks of acute rheumatic fever or post-streptococcal glomerulonephritis 1
- Outbreaks in closed settings (schools, military barracks) 1
- Patients who remain symptomatic or have recurrent symptoms 1
Management of Recurrent Episodes
Consider that the patient may be a chronic pharyngeal GAS carrier experiencing repeated viral infections rather than true recurrent streptococcal infections. 1
For a Single Recurrence
- Retreat with standard regimens (penicillin, amoxicillin, or alternatives) 3
- Consider intramuscular benzathine penicillin G if compliance is questionable 3
For Multiple Recurrences
Use antibiotics with higher eradication rates in carrier states:
- Clindamycin 7 mg/kg 3×/day (max 300 mg/dose) for 10 days 1, 3
- Amoxicillin-clavulanate 80-90 mg/kg/day of amoxicillin component divided 2×/day for 10 days 1, 3
- First-generation cephalosporin for 10 days 1
Important distinction: Viral features (cough, congestion, ear pain, sinus drainage) in a patient with positive GAS testing suggest carrier state with intercurrent viral infection rather than true GAS pharyngitis. 3
Household Contacts and Transmission
Do NOT test or treat asymptomatic household contacts—screening or prophylactic treatment is not recommended. 1, 2
- Up to one-third of household members may be asymptomatic carriers 1, 2
- Prophylactic treatment does not reduce subsequent infection rates 1, 2
- Consider testing family members only when multiple repeated episodes suggest "ping-pong" transmission 3
Common Pitfalls to Avoid
- Never prescribe antibiotics based on clinical appearance alone (exudates, white patches)—these overlap too broadly between viral and bacterial causes 2
- Never order backup throat culture in adults with negative RADT—this wastes resources without clinical benefit 2
- Never treat asymptomatic carriers identified by routine screening—they do not require treatment 1
- Never perform routine post-treatment testing in asymptomatic patients—positive results likely reflect carrier state 1
- Recognize that up to 70% of sore throat patients receive unnecessary antibiotics when only 20-30% of children and 5-10% of adults actually have GAS pharyngitis 2
Timeline and Return to Activities
- Clinical improvement typically occurs within 24-48 hours of starting appropriate antibiotics 4
- Patients are no longer contagious after 24 hours of appropriate antibiotic therapy 4
- Complete bacterial eradication requires the full 10-day course even though symptoms improve earlier 4
- Patients may return to school/work after 24 hours of antibiotics and symptom improvement 4