What is the treatment for a suspected Streptococcus (Strep) infection, such as pharyngitis or pneumonia, in an adult or child?

Treatment of Streptococcal Infections

First-Line Treatment for Confirmed Group A Streptococcal Pharyngitis

Penicillin or amoxicillin for 10 days is the definitive first-line treatment for confirmed Group A streptococcal pharyngitis in both adults and children. 1, 2, 3

Antibiotic Selection and Dosing

• Penicillin V or amoxicillin are the drugs of choice for treating confirmed GAS pharyngitis, with treatment duration of 10 days required to eradicate the organism and prevent acute rheumatic fever 1, 3
• Amoxicillin is FDA-approved for upper respiratory tract infections caused by susceptible (β-lactamase-negative) Streptococcus species, including α- and β-hemolytic isolates 2
• Treatment should be taken at the start of meals to minimize gastrointestinal intolerance 2
• Continue treatment for a minimum of 48-72 hours beyond when the patient becomes asymptomatic 2

Penicillin-Allergic Patients

• First-generation cephalosporins are recommended for patients with nonanaphylactic penicillin allergies 3
• Clindamycin is a reasonable alternative, with approximately 1% resistance among GAS isolates in the United States 1
• Macrolides (erythromycin, clarithromycin) or azithromycin can be used, but macrolide resistance rates are 5-8% in most U.S. areas, with significant resistance in some regions 1, 3
• Azithromycin is given for 5 days (12 mg/kg/day, maximum 500 mg), while other macrolides require 10 days of therapy 1
• Important caveat: Azithromycin should not be relied upon to prevent rheumatic fever, and susceptibility testing should be performed when using macrolides 4

Diagnosis Before Treatment

Antibiotics should ONLY be prescribed after laboratory confirmation of GAS pharyngitis by rapid antigen detection test (RADT) or throat culture. 1, 5

Testing Algorithm

• Use clinical decision rules (Centor criteria) to assess probability of GAS infection 5
• Adults: A negative RADT is sufficient to rule out GAS pharyngitis; backup throat culture is NOT necessary 1, 5, 6
• Children and adolescents: A negative RADT MUST be confirmed with throat culture before withholding antibiotics, due to 10-20% false-negative rate and higher risk of rheumatic fever 1, 6
• RADT sensitivity is 80-90% with specificity ≥95% 6

Clinical Features Suggesting Viral Etiology (Do NOT Test or Treat)

• Presence of cough, rhinorrhea, hoarseness, or oral ulcers strongly suggests viral pharyngitis 5, 7
• Testing for GAS is not necessary when these features are present 7
• Only 5-15% of adult pharyngitis cases are actually caused by GAS, yet over 60% receive antibiotics—representing massive overtreatment 5

Symptomatic Management for All Patients

Every patient with pharyngitis should receive symptomatic care regardless of whether antibiotics are prescribed. 1, 5

Pain and Fever Control

• NSAIDs (ibuprofen) or acetaminophen for moderate to severe symptoms or fever control 1, 7
• Avoid aspirin in children due to risk of Reye syndrome 1, 7
• Topical anesthetics (throat lozenges, sprays with benzocaine, lidocaine) may provide temporary relief 1, 7
• Warm salt water gargles for patients old enough to gargle 1, 7

What NOT to Use

• Corticosteroids are NOT recommended for routine pharyngitis treatment—they reduce symptom duration by only ~5 hours with potential adverse effects 1, 7
• Antibiotics shorten symptom duration by only 1-2 days, with number needed to treat of 6 at 3 days and 21 at 1 week 5

Treatment Justification and Expected Outcomes

The primary justification for treating confirmed GAS pharyngitis is preventing acute rheumatic fever, peritonsillar abscess, and reducing transmission. 5

• Treatment within 9 days of symptom onset still effectively prevents acute rheumatic fever 6
• Antibiotics do NOT prevent post-streptococcal glomerulonephritis 8
• Most pharyngitis (viral or bacterial) resolves in less than 1 week regardless of treatment 5, 7
• Reassure patients that typical pharyngitis is self-limited 5

Follow-Up and Special Situations

Post-Treatment Testing

• Routine follow-up throat cultures or rapid tests are NOT recommended after completing appropriate antibiotic treatment in asymptomatic patients 6
• A positive post-treatment test does not distinguish between carrier state and active infection 6
• Follow-up testing may be considered only in special circumstances: multiple recurrent episodes, history of acute rheumatic fever, or outbreaks in closed settings 6

Household Contacts

• Do NOT test or treat asymptomatic household contacts, even with history of recurrent infections 1, 6
• Up to one-third of households include asymptomatic GAS carriers who do not require treatment 6
• Prophylactic treatment of contacts has not been shown to reduce subsequent GAS pharyngitis incidence 6

When to Reevaluate

• Patients with worsening symptoms after appropriate antibiotic initiation or symptoms lasting >5 days after starting treatment should be reevaluated for suppurative complications or alternative diagnoses 6, 3

Streptococcal Pneumonia Treatment

For severe pneumococcal pneumonia, intravenous ceftriaxone, cefotaxime, or amoxicillin-clavulanic acid are appropriate choices, as serum and pulmonary levels achieved are several times higher than the minimal inhibitory concentration of resistant strains 9