What is the recommended treatment for acute pharyngitis in pregnancy, particularly when caused by Group A Streptococcus (GAS)?

Treatment of Acute Pharyngitis in Pregnancy

First-Line Treatment: Penicillin or Amoxicillin

For pregnant patients with confirmed Group A Streptococcal pharyngitis, penicillin or amoxicillin remains the treatment of choice due to proven safety in pregnancy, narrow spectrum, and absence of documented resistance. 1

Recommended Regimens for Non-Allergic Patients

• Penicillin V: Standard oral dosing for 10 days is the reference treatment, offering proven efficacy with a narrow antimicrobial spectrum 1, 2
• Amoxicillin: Equally effective alternative that may be preferred for better palatability and adherence; can be dosed once daily (50 mg/kg, maximum 1000 mg) for 10 days 1, 3
• Benzathine penicillin G: Single intramuscular injection is particularly useful when adherence to oral therapy is uncertain 1

The critical advantage of penicillin-based therapy is that penicillin-resistant GAS has never been documented anywhere in the world, making it uniquely reliable 3. The 10-day duration is essential to achieve maximal pharyngeal eradication of GAS 1.

Treatment for Penicillin-Allergic Pregnant Patients

Non-Anaphylactic Penicillin Allergy

First-generation cephalosporins (cephalexin or cefadroxil) for 10 days are the preferred alternatives, as they have a cross-reactivity risk with penicillin of less than 3% 1, 4. These narrow-spectrum agents are superior to broad-spectrum cephalosporins (cefdinir, cefixime, cefuroxime) which unnecessarily increase selection pressure for antibiotic-resistant flora 3, 5.

Anaphylactic Penicillin Allergy

For patients with immediate hypersensitivity reactions to penicillin:

• Clindamycin: 600 mg/day in 2-4 divided doses for 10 days in adults; particularly effective with only 1% resistance in the United States 1, 4
• Azithromycin: 500 mg once, then 250 mg daily for 4 days (5-day course total); however, macrolide resistance rates are approximately 5-8% in the US, making this less reliable 3, 6
• Clarithromycin: 250 mg twice daily for 10 days is an alternative macrolide option 1

Important caveat: Up to 10% of penicillin-allergic persons are also allergic to cephalosporins, so cephalosporins should never be used in patients with anaphylactic-type hypersensitivity to penicillin 3, 5.

Critical Pregnancy-Specific Considerations

Avoid Aminopenicillins if Infectious Mononucleosis Suspected

If there is any clinical suspicion of concurrent infectious mononucleosis (which can present similarly to streptococcal pharyngitis), avoid ampicillin and amoxicillin and instead use a first-generation cephalosporin or macrolide 4. The aminopenicillin-mononucleosis interaction can cause a characteristic rash.

Rifampin Contraindication

Rifampin, which is sometimes added to penicillin for recurrent or difficult-to-eradicate infections, is relatively contraindicated in pregnant women 1. This limits treatment options for recurrent pharyngitis during pregnancy.

Diagnostic Confirmation Required

Always confirm GAS pharyngitis with throat culture or rapid antigen detection testing (RADT) before initiating antibiotics 1, 4. This is particularly important in pregnancy to avoid unnecessary antibiotic exposure, as most pharyngitis cases are viral and do not require antibiotics 1.

Treatment Algorithm for Pregnant Patients

1. Confirm diagnosis: Throat culture or RADT positive for GAS 1
2. Assess penicillin allergy history:
   • No allergy → Penicillin V or amoxicillin × 10 days 1
   • Non-anaphylactic allergy → Cephalexin or cefadroxil × 10 days 1, 4
   • Anaphylactic allergy → Clindamycin × 10 days (preferred) or azithromycin × 5 days 1, 3
3. Avoid rifampin in all pregnant patients 1
4. Consider infectious mononucleosis if atypical features present; avoid aminopenicillins if suspected 4

Post-Treatment Management

• No routine follow-up cultures are needed for asymptomatic patients who complete therapy 1, 4
• Patients become non-contagious after 24 hours of appropriate antibiotic therapy 4
• Do not test or treat asymptomatic household contacts, as this is not routinely recommended 1

Common Pitfalls to Avoid

• Using broad-spectrum cephalosporins (cefdinir, cefixime, cefuroxime) as first-line therapy when narrow-spectrum options are available and appropriate 3, 5
• Treating without microbiological confirmation, leading to unnecessary antibiotic exposure in viral pharyngitis 1
• Shortening treatment duration below 10 days for most antibiotics, which reduces eradication rates 1
• Using macrolides as first-line therapy when penicillin or cephalosporins can be used, given rising macrolide resistance 3