What are the treatment guidelines for a pregnant woman with a sore throat suspected to be Group B Streptococcus (GBS)?

Treatment of Sore Throat Suspected to be Group B Streptococcus

GBS Does Not Cause Pharyngitis - No Treatment Indicated

Group B Streptococcus (GBS) is not a pathogen of the pharynx and does not cause sore throat. GBS colonizes the gastrointestinal and genitourinary tracts, not the upper respiratory tract 1, 2. If GBS is isolated from a throat culture, it represents colonization or laboratory contamination, not infection.

What Actually Causes Bacterial Pharyngitis

The relevant bacterial pathogen for sore throat is Group A Streptococcus (Streptococcus pyogenes), not Group B Streptococcus 2. These are completely different organisms with different clinical significance:

• Group A Strep: Causes pharyngitis, requires treatment to prevent rheumatic fever and suppurative complications
• Group B Strep: Colonizes vaginal-rectal areas, causes neonatal sepsis and UTIs, but does NOT cause pharyngitis 3, 1, 2

Clinical Approach to Sore Throat

For a patient presenting with sore throat:

• Test for Group A Streptococcus using rapid antigen detection test or throat culture
• Do not treat if GBS is incidentally isolated from throat culture, as this represents colonization only 2
• Treat Group A Strep pharyngitis with penicillin or amoxicillin if confirmed

Special Consideration: If Patient is Pregnant

Even in pregnancy, GBS pharyngeal colonization requires no treatment 1, 4. However, pregnant women should undergo vaginal-rectal GBS screening at 36 0/7 to 37 6/7 weeks' gestation to guide intrapartum antibiotic prophylaxis during labor 5, 6.

When GBS Treatment IS Indicated in Pregnancy

GBS treatment is only indicated in these specific scenarios 1, 7:

• GBS bacteriuria (any concentration in urine): Treat the UTI immediately AND provide intrapartum prophylaxis during labor 1, 7
• Positive vaginal-rectal screening culture: Intrapartum IV antibiotics during active labor only (penicillin G 5 million units IV initially, then 2.5 million units IV every 4 hours until delivery) 1, 5
• Previous infant with GBS disease: Automatic intrapartum prophylaxis 3, 4

Critical Pitfall to Avoid

Never treat asymptomatic GBS colonization (vaginal, rectal, or pharyngeal) with oral or IV antibiotics outside of labor 1, 2. The CDC explicitly states that antimicrobial agents should not be used before the intrapartum period to treat GBS colonization, as such treatment is ineffective in eliminating carriage and may cause adverse consequences including antibiotic resistance 1, 4.

Summary Algorithm

1. Patient with sore throat → Test for Group A Streptococcus, not Group B
2. If GBS isolated from throat → No treatment needed; this is colonization 2
3. If patient is pregnant with GBS anywhere → Only treat if GBS bacteriuria present; otherwise wait for labor to give IV prophylaxis 1, 5
4. Intrapartum prophylaxis timing → Must be administered ≥4 hours before delivery for maximum 78% effectiveness in preventing neonatal disease 3, 8