What antibiotics are recommended for a pregnant patient with a Group A streptococcus (Strep A) positive sore throat?

Treatment of Group A Streptococcal Pharyngitis in Pregnancy

Penicillin V (500 mg orally twice daily for 10 days) or amoxicillin (500 mg orally three times daily for 10 days) are the first-line antibiotics for treating Group A streptococcal pharyngitis in pregnant women. 1

First-Line Treatment Approach

Penicillin remains the treatment of choice for Group A streptococcal pharyngitis during pregnancy due to its proven efficacy, safety profile, narrow spectrum of activity, and low cost. 2 The recommended regimens are:

• Penicillin V: 250 mg three times daily or four times daily, OR 500 mg twice daily for 10 days 2, 1
• Amoxicillin: 500 mg three times daily for 10 days (often preferred in young children due to better taste acceptance, but equally effective in adults) 2, 1

The full 10-day course is essential to achieve maximal pharyngeal eradication of Group A streptococci and prevent rheumatic fever, regardless of symptom improvement. 2, 1 Penicillins and cephalosporins are considered the safest antibiotic classes during pregnancy, with decades of clinical experience documenting their safety for the fetus. 3, 4, 5

Alternative for Intramuscular Administration

Benzathine penicillin G (1.2 million units intramuscularly as a single dose) is the preferred option for patients who are unlikely to complete a full 10-day oral course. 2 This single-dose regimen ensures compliance and has proven efficacy in preventing rheumatic fever. 2

Management of Penicillin-Allergic Pregnant Patients

For Patients WITHOUT High Risk of Anaphylaxis

Cefazolin is the preferred alternative for pregnant women with penicillin allergy who do not have a history of immediate hypersensitivity reactions (anaphylaxis, angioedema, or urticaria). 1 First-generation cephalosporins are acceptable alternatives and should be administered for 10 days. 2

Important caveat: Approximately 10% of patients with penicillin allergy also have cross-reactivity to cephalosporins, so careful allergy history is essential. 6

For Patients WITH High Risk of Anaphylaxis

Clindamycin (300 mg orally four times daily for 10 days) is recommended if susceptibility testing confirms the streptococcal isolate is susceptible to clindamycin. 1 Erythromycin is also a suitable alternative for penicillin-allergic patients, though less than 5% of Group A streptococci in the United States show resistance to erythromycin. 2

Critical consideration: Clindamycin should only be used if susceptibility is confirmed, as resistance can occur. 1

Antibiotics to Strictly Avoid During Pregnancy

The following antibiotics are contraindicated during pregnancy due to fetal risks:

• Tetracyclines (including doxycycline): Should not be used after the fifth week of pregnancy due to effects on fetal bone and teeth development 3, 6
• Fluoroquinolones: Contraindicated due to potential cartilage toxicity in the fetus 4, 6
• Sulfonamides: Should be avoided, particularly near term 2, 6
• Trimethoprim-sulfamethoxazole: Should be avoided 1
• Aminoglycosides: Should be avoided due to ototoxicity and nephrotoxicity risks 3, 6

Essential Clinical Considerations

Treatment should only be initiated after positive confirmation via throat culture or rapid antigen detection test (RADT) for Group A streptococci. 1 Withholding antibiotics in patients with negative microbiological tests is a quality care indicator. 1

Therapy can be safely delayed up to 9 days after symptom onset and still prevent rheumatic fever, allowing time for laboratory confirmation before starting antibiotics. 2 This flexibility permits clinicians to avoid unnecessary antibiotic exposure while awaiting test results.

Asymptomatic carriers do not require treatment, as antimicrobial therapy is much less effective at eradicating Group A streptococci from carriers than from patients with acute infections. 1

Common Pitfalls to Avoid

• Do not use shorter courses (such as 3-5 days) of antibiotics, even though some newer agents have been studied for shorter durations. Evidence is insufficient to recommend these regimens, and the standard 10-day course remains necessary. 2
• Do not prescribe broad-spectrum antibiotics when narrow-spectrum penicillin is effective, as this promotes antibiotic resistance and increases costs. 2
• Do not treat based on clinical symptoms alone without microbiological confirmation, as viral pharyngitis is far more common and cannot be reliably distinguished clinically. 1
• Do not discontinue therapy early even if symptoms resolve, as incomplete eradication increases the risk of rheumatic fever and treatment failure. 1