1. Group B Streptococcus
An overview of risk factors, screening, and treatment for moms and babies
Erin Burnette, FNP
February 2011
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2. What is Group B Strep (GBS)?
A bacteria that is often found in the GI tract that can colonize the vagina in some women
Colonization can be transient.
Gram positive
Also known as Streptococcus agalactiae
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3. GBS and pregnancy
GBS in pregnancy can cause miscarriage, endometritis, bacteremia, and chorioamnionitis.
GBS infection can also affect the baby leading to still birth, prematurity, or invasive neonatal disease.
Because of these potential consequences, pregnant women are screened prenatally.
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4. Transmission
Infants can acquire GBS from the mother through vertical transmission from the vagina during labor.
GBS can be transmitted through intact membranes but this is not common.
The infant can become sick from GBS, or become colonized and remain healthy.
Aspirating GBS into fetal lungs can lead to bacteremia.
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5. Universal Screening
Universal culture based screening has been shown to be more effective than risk based screening.
Testing is done between weeks
Vaginal and rectal areas are swabbed
If a woman had GBS UTI during pregnancy, culture may not be done as she automatically would be treated as GBS +.
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6. Neonatal Early Onset GBS infection
May cause pneumonia, sepsis, meningitis
Onset usually within 24 hours (60-70%)
32% of cases identified between 24-48h.
<8% of cases identified after 48 hours.
Rapid clinical decline common with early onset disease.
Incidence: 0.4 per every
1000 live births.
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7. Signs/Symptoms of sepsis
Usually general, nonspecific, and nonlocalizing:
Temperature instability
Respiratory distress
Lethargy
Feeding problems
Jaundice
Apnea
Some symptoms can be more severe:
Purpura
Seizures
90% of babies show symptoms within 24 hours of life.
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8. At Risk?
Presence of certain risk factors make infants at higher risk of GBS infection.
Gestational age <37 weeks, ROM >18 hours, intraamniotic infection, young mothers, black race, and previous infant with invasive disease.
Low levels of maternal GBS antibody may also be a risk factor.
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9. Infants Immature Immune system
Limitations in neutrophil production
Impaired/immature neutrophils don’t function properly
More likely to exhaust marrow reserves if stressed, such as in sepsis
Preterm infants have less vernix, which has been shown to play a role in host defense
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10. Labs
CBC drawn early in life may not always be helpful in determining risk of sepsis.
Blood cultures can be helpful. Studies have shown median time for a blood culture to become positive with GBS: hours. Positive with other organisms: hours.
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11. Late Onset GBS infection
May present between 1-3 months of life.
Often presents as bacteremia or meningitis.
Not seen in the newborn nursery period due to timing of onset.
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12. Complications of GBS infection
GBS infection can lead to developmental delay, blindness, deafness, as well as other neurological impairments.
GBS can also lead to death. Risk of death is generally inversely related to gestational age and birth weight.
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13. Maternal Treatment Recommendations
Intrapartum antibiotic treatment given intravenously can reduce risk of vertical transmission.
Goal: Reach adequate circulating levels of the antibiotic in maternal and fetal circulation without reaching toxic levels.
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14. Intrapartum Antibiotic Therapy…
Moms in labor should get IV antibiotics if:
1. + GBS culture late in gestation.
2. Unknown GBS status delivering before 37 weeks.
3. ROM >18 hours
4. Previous infant with GBS disease
5. GBS bacturia during pregnancy
6. Maternal temp of 100.4/38 ̊
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15. …Intrapartum Antibiotic Therapy
GBS is susceptible to Penicillin and Amoxicillin
If mom has a mild PCN allergy, may use Cefazolin
If mom has a history of anaphylactic type reaction to PCN, may use Clindamycin or Vancomycin
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16. What About?? C/S prior to labor onset with intact membranes?
Risk of vertical transmission very low.
Routine screening still indicated in case ROM or labor starts before c/s.
If no risk factors, intrapartum antibiotics not necessarily indicated.
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17. Adequacy of Treatment In order to be deemed “adequate treatment”:
1. IV administration of a beta lactam antibiotic (such as PCN 5mu) at least 4 hours prior to delivery.
2. Continue maintenance dosing q4 hours until delivery (such as PCN 3mu)
3. Antibiotic given was PCN, ampicillin, or cefazolin
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18. What do we do in the nursery?
Suggestions from the new 2010 CDC guidelines
New CDC algorithms, click link for:
Indications for intrapartum antibiotics and Treatment of the infant
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19. Newborn Nursery GBS Algorithm
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20. Treatment of the infant: signs of sepsis present
These infants need a full diagnostic workup (CBC & blood culture, and a CXR if respiratory distress is significant, and LP if condition warrants).
Antibiotics should be started and continued until results of evaluation are complete.
IV ampicillin and gram – coverage, often gentamicin.
These infants most often go to NICU.
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21. Treatment of the Infant: maternal diagnosis of chorioamnionitis:
S/Sx of “chorio”: maternal fever, uterine tenderness, maternal or fetal tachycardia, foul/purulent amniotic fluid.
These infants should undergo a limited diagnostic evaluation (CBC and blood culture).
Give antibiotics pending results of the culture.
Observe for 48 hours.
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22. Treatment of the Infant: well appearing w/ inadequate maternal abx
It can be appropriate to monitor the infant clinically for signs of sepsis.
Well appearing infant >37 weeks with ROM <18 hours: monitor for 48 hours.
Well appearing infant <37 weeks &/or ROM >18 hours: limited evaluation and monitor for 48 hours.
Use clinical judgment!
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23. Treatment of the Infant: Well appearing infant (any GA) w/ adequate maternal abx
Observe clinically for hours
Usually do not need a workup
If ALL discharge criteria are met at 24 hours, can consider discharge.
Be sure to educate family on home observation and ensure adequate medical follow up.
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24. Treatment of the Infant: Maternal GBS status unknown
GBS status can be unknown due to lack of prenatal care, lack of prenatal records, premature delivery, etc.
Obstetrically, these moms should be managed according to risk factors (gestational age, length of ROM, etc) and treated as appropriate.
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25. When GBS is negative GBS negative means LOW risk but not NO risk. Why?
False negative rates have been reported from 4-8%. Why?
Transient nature of GBS, errors in specimen collection/lab processing.
FYI: 60% of infants with GBS disease were born to GBS negative mothers.
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26. Other bugs causing neonatal sepsis
While GBS is the most common organism causing early onset sepsis, it isn’t the only one.
Others include E. Coli, H. influenzae, and coagulase negative staphyloccus.
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27. Future Research Maternal Vaccine against GBS!
This has been difficult due to ethical issues with pregnant women in clinical trials.
Also, EOS GBS is not extremely common, so it can be a difficult outcome to measure.
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28. References
Centers for Disease Control and Prevention. (2010). Prevention of Perinatal Group B Streptococcal Disease MMWR. CDC.
Illuzzi, J., & Bracken, M. (2006). Duration of Intrapartum Prophylaxis for Neonatal Group B Streptococcal Disease. Obstetrics and Gynecology , 108 (5),
Jardine, L., Davies, M., & Faoagali, J. (2006). Incubation Time Required for Neonatal Blood Cultures to Become Positive. Journal of Paediatrics and Child Health ,
Koenig, J., & Keenan, W. (2009). Group B Streptococcus and Early- Onset Sepsis in the Era of Maternal Prophylaxis. Pediatric Clinics of North America , 56 (3).
Merenstein, G., & Gardner, S. (2002). Handbook of Neonatal Intensive Care (Fifth ed.). St. Louis: Mosby.
Verani, J., & Schrag, S. (2010). Group B Streptococcal Disease in Infants: Progress in Prevention and Continued Challenges. Clinics in Perinatology , 37,
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