Group B Streptococcus (GBS) in Pregnancy

• Group B Streptococcus (GBS), or Streptococcus agalactiae, commonly colonizes the vagina and rectum of healthy women.
• GBS is a leading cause of neonatal infections that can result in significant morbidity and mortality.

Prevalence

• Approximately 10-30% of pregnant women are colonized with GBS.
• Colonization rates can vary based on geographic location, race, and parity.
• GBS colonization is usually transient or intermittent.
• Colonization doesn't typically cause symptoms in pregnant women.

Screening

• Universal screening for GBS is recommended for all pregnant women.
• Screening involves vaginal and rectal swab cultures.
• Optimal screening time is 35-37 weeks gestation.
• Women with GBS detected during screening are considered GBS positive.

Risk Factors

• Intrapartum fever is a risk factor for GBS.
• Prolonged rupture of membranes is a risk factor.
• Preterm labor is a risk factor.
• A previous infant with GBS disease is a risk factor.
• GBS bacteriuria during the current pregnancy is a risk factor.

Transmission

• Infants are typically exposed to GBS during passage through the birth canal.
• Vertical transmission from mother to infant can occur in utero or postpartum, but it's less common.
• Not all infants born to GBS-positive mothers will develop GBS disease.
• The risk of transmission can be reduced with intrapartum antibiotic prophylaxis (IAP).

Neonatal GBS Disease

• Early-onset disease (EOD) occurs within the first 7 days of life, usually within 24 hours.
• Late-onset disease (LOD) occurs between 7 days and 3 months of age.
• EOD is more common and is usually acquired from the mother during delivery.
• LOD is usually acquired from the mother, but can also be acquired from other sources.

Clinical Manifestations in Neonates

• Sepsis is a manifestation, presenting as lethargy, poor feeding, and temperature instability.
• Pneumonia is a manifestation, presenting as respiratory distress.
• Meningitis is a manifestation, presenting as fever, irritability, and poor feeding.
• Long-term neurological sequelae can occur.

Intrapartum Antibiotic Prophylaxis (IAP)

• IAP involves administering antibiotics during labor to reduce the risk of neonatal GBS disease.
• IAP is recommended for GBS-positive women.
• IAP is recommended for women with unknown GBS status who have risk factors such as preterm labor, prolonged rupture of membranes, or intrapartum fever.
• Penicillin is the preferred antibiotic for IAP.
• Alternatives for penicillin-allergic women include cefazolin, clindamycin, or vancomycin.

Penicillin Allergy

• Women with a penicillin allergy should be tested to determine the severity of the allergy.
• Women with a severe penicillin allergy should receive clindamycin or vancomycin.
• Clindamycin susceptibility testing should be performed, as some GBS strains are resistant to clindamycin.
• Vancomycin should be used if GBS is resistant to clindamycin.

Management of GBS-Positive Women

• GBS-positive women should receive IAP during labor.
• IAP should be initiated at least 4 hours before delivery to be effective.
• Women undergoing planned cesarean delivery before the onset of labor and with intact membranes do not need IAP.
• Women with a history of GBS bacteriuria during the current pregnancy should receive IAP.

Management of Women with Unknown GBS Status

• Women with unknown GBS status who are in preterm labor or have prolonged rupture of membranes should receive IAP pending GBS culture results.
• Rapid GBS testing can be performed to guide IAP decisions.
• If rapid GBS testing is not available, broad-spectrum antibiotics should be administered.

Prevention Strategies

• Universal GBS screening is a key prevention strategy.
• Adherence to IAP guidelines is crucial.
• Education of pregnant women about GBS is important.
• Ongoing surveillance of GBS disease rates is necessary.

Impact of IAP

• IAP has significantly reduced the incidence of early-onset GBS disease.
• IAP has not eliminated GBS disease entirely.
• Late-onset GBS disease rates have not been significantly affected by IAP.
• There are potential risks associated with IAP, such as antibiotic resistance and allergic reactions.
• The benefits of IAP generally outweigh the risks.

Alternative Therapies

• Vaginal cleansing with antiseptic solutions has been studied as a potential alternative to IAP, but is not currently recommended.
• Probiotics have been studied as a potential way to reduce GBS colonization, but more research is needed.
• Garlic has been studied as a potential way to reduce GBS colonization, but more research is needed.

Future Directions

• Research is ongoing to develop a GBS vaccine.
• Rapid GBS testing at the point of care is being developed.
• Personalized approaches to IAP are being explored.
• Understanding the mechanisms of GBS colonization and transmission is important for developing new prevention strategies.

Ethical Considerations

• Informed consent for GBS screening and IAP is important.
• Balancing the benefits and risks of IAP is necessary.
• Ensuring equitable access to GBS screening and treatment is crucial.
• Respecting patient autonomy and cultural beliefs is important.

Conclusion

• Group B Streptococcus is a common bacterium that can cause serious infections in newborns.
• Universal screening for GBS is recommended for all pregnant women.
• Intrapartum antibiotic prophylaxis is effective in reducing the risk of early-onset GBS disease.
• Ongoing research and surveillance are needed to further reduce the burden of GBS disease.

This lesson covers Group B Streptococcus (GBS) colonization in pregnant women, its prevalence, screening methods, and associated risk factors. Universal screening is recommended via vaginal and rectal swab cultures between 35-37 weeks gestation to prevent neonatal infections.