What antibiotic can be prescribed for pregnant women with strep (streptococcal) throat?

Antibiotic Treatment for Streptococcal Infections in Pregnant Women

For pregnant women with streptococcal infections, penicillin remains the first-line antibiotic of choice due to its proven safety profile, narrow spectrum of activity, and effectiveness. 1

Treatment Algorithm for Group B Streptococcus (GBS)

Non-Penicillin Allergic Patients:

• First choice: Penicillin G, 5 million units IV initial dose, then 2.5 million units IV every 4 hours until delivery 1
• Alternative: Ampicillin, 2 g IV initial dose, then 1 g IV every 4 hours until delivery 1

Penicillin-Allergic Patients:

1. Low risk for anaphylaxis (no history of anaphylaxis, angioedema, respiratory distress, or urticaria):

   • Cefazolin, 2 g IV initial dose, then 1 g IV every 8 hours until delivery 1

2. High risk for anaphylaxis (history of immediate hypersensitivity reactions):

   • If GBS isolate is susceptible to both clindamycin and erythromycin:
     • Clindamycin, 900 mg IV every 8 hours until delivery 1
   • If susceptibility testing is not available or shows resistance:
     • Vancomycin, 1 g IV every 12 hours until delivery 1

Treatment for Streptococcal Pharyngitis (Group A Strep)

Non-Penicillin Allergic Patients:

• First choice: Penicillin V, 500 mg orally twice daily for 10 days 1
• Alternative: Amoxicillin, often used in place of penicillin V especially for young children 1

Penicillin-Allergic Patients:

• Erythromycin, 500 mg orally four times daily for 10 days 1, 2
• For urogenital infections during pregnancy due to Chlamydia trachomatis: Erythromycin 500 mg orally four times daily for at least 7 days 2

Important Considerations

Penicillin Allergy Testing

• Most pregnant women reporting penicillin allergy (89% in one study) have negative skin tests and can safely receive penicillin 3
• Consider penicillin allergy testing during pregnancy for women with reported allergies, as this can reduce unnecessary use of alternative antibiotics 4

Antibiotic Resistance

• Increasing resistance to clindamycin (21%) and erythromycin (29%) among GBS isolates has been reported 5
• Susceptibility testing should be performed on GBS isolates from penicillin-allergic women 1

Physiological Changes in Pregnancy

• Pregnancy causes increased glomerular filtration rate, increased total body volume, and enhanced cardiac output, which may affect antibiotic pharmacokinetics 6
• Dose adjustments may be necessary for some antibiotics during pregnancy

Potential Pitfalls and Caveats

1. Do not treat GBS colonization before labor: Antimicrobial agents should not be used before the intrapartum period to treat GBS colonization. Such treatment is not effective in eliminating carriage or preventing neonatal disease 1

2. Planned cesarean delivery: GBS-colonized women who have a planned cesarean delivery performed before rupture of membranes and onset of labor do not routinely require intrapartum chemoprophylaxis 1

3. Avoid azithromycin for strep throat: While azithromycin is sometimes used for strep throat, penicillin remains the drug of choice to prevent rheumatic fever 1, 7

4. Monitor for resistance: Due to increasing resistance to clindamycin and erythromycin, susceptibility testing is crucial when these antibiotics are considered 1, 5

5. Duration of therapy: For streptococcal pharyngitis, a full 10-day course of antibiotics is recommended to prevent rheumatic fever, even if symptoms resolve earlier 1

By following these evidence-based recommendations, clinicians can effectively treat streptococcal infections in pregnant women while minimizing risks to both mother and baby.