Obstetrics Book

Fetal Disorders

Perinatal Disorders

Prevention

  • Group B Streptococcus Prophylaxis

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Group B Streptococcus ProphylaxisAka: Group B Strep Prophylaxis, GBS Prophylaxis

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  1. Epidemiology
    1. Asymptomatic GBS carriers: 15-40% of all pregnancies
    2. Treatment for risk factors prevents 70% Neonatal GBS
  2. See Also
    1. Group B Streptococcal Sepsis
  3. Indications for Intrapartum GBS Prophylaxis
    1. Known maternal GBS colonization
    2. Preterm Labor
    3. Preterm Premature Rupture of Membranes
    4. Prolonged Rupture of Membranes exceeding 18 hours
      1. Consider starting antibiotics at 12 hours after ROM
      2. Allows for 2 doses of antibiotics prior to delivery
    5. Prior infant with Group B Streptococcal Sepsis
    6. Multiple Gestation
    7. Maternal intrapartum Fever
  4. Indications for screening for GBS Culture
    1. All pregnant women should be cultured at 35-37 weeks
      1. Current CDC guidelines recommend universal screening
      2. (1996) MMWR Morb Mortal Wkly Rep 45:1
    2. Preterm Labor
    3. Preterm Rupture of Membranes
    4. Pregnant women undergoing surgery of cervix
  5. Management: Antibiotics in peripartum until delivery
    1. First line agents
      1. Penicillin G 5 MU IV, then 2.5 MU IV q4 hours
        1. Preferred first line agent
      2. Ampicillin 2 grams IV, then 1 gram every 4 hours
        1. Penicillin G is preferred
    2. Penicillin Allergy (not Anaphylaxis)
      1. Cefazolin 2 grams IV, then 1 gram every 6 hours
    3. Penicillin Anaphylaxis
      1. Growing resistance to Clindamycin and Erythromycin
        1. Manning (2003) Obstet Gynecol 101:74
      2. Agents
        1. Erythromcin 500 mg IV every 6 hours
        2. Clindamycin 900 mg IV every 8 hours
        3. Vancomycin 1g IV every 12 hours
          1. Indicated if GBS Antibiotic Resistance suspected
    4. Other options
      1. Cephalothin 2 grams IV, then 1 gram every 6 hours
  6. Management: Infant born to mother with known GBS
    1. Path 1: Full Neonatal Sepsis evaluation
      1. Indications
        1. Signs of Sepsis in the newborn
        2. Mother treated for suspected Chorioamnionitis
    2. Path 2: Limited Sepsis evaluation
      1. Indications
        1. Antibiotics <4 hours before delivery
        2. Gestational age <35 weeks
      2. Protocol
        1. Observe infant for 48 hours
        2. Evaluate per Neonatal Sepsis protocol
          1. Complete Blood Count
          2. Blood Culture
      3. Antibiotic indications
        1. White Blood Cell count >30k or <5k
        2. Temperature instability
          1. Newborn Temperature < 97 F (36 C)
          2. Newborn Temperature > 99.6 F (37 C)
        3. Other clinical criteria suggestive of infection
    3. Path 3: Observation
      1. Indications
        1. Antibiotics 4 or more hours before delivery
        2. Term, healthy appearing newborn
      2. Protocol
        1. No additional management unless dictated by exam
        2. Observe for 48 hours prior to discharge
  7. Special concerns
    1. Intrauterine monitoring is not contraindicated
      1. FSE and IUPC does not increase neonatal GBS risk
    2. GBS colonization must be reassessed in each pregnancy
      1. Use current GBS status to guide chemoprophylaxis
      2. Prophylaxis not mandated by prior GBS colonization
        1. Only indicated if current pregnancy GBS positive
  8. References
    1. Apgar (2003) AAFP Board Review, Seattle
    2. Morrison (2000) ALSO, p. 14-5
    3. Apgar (2005) Am Fam Physician 71:903

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