For Physicians. By Physicians.™

Updated Guidance on GBS Screening and Prophylaxis


Group B streptococcal (GBS) disease remains a leading cause of early-onset neonatal sepsis in the US. The ACOG committee opinion has been endorsed by the AAP, ACNM, AWHONN and SMFM. Furthermore, CDC states that the ACOG committee opinion supersedes the 2010 CDC recommendations.

Updates to note:

  • Universal screening with a window of 36w0d – 37w6d
  • Alert lab to penicillin allergy so that clindamycin susceptibility testing can be performed on GBS culture positive specimen
  • Vancomycin dosing is now weight based
  • Unknown culture status and in labor at ≥37w0d
    • Administer intrapartum prophylaxis if GBS colonized in previous pregnancy
  • Penicillin still remains agent of choice for intrapartum prophylaxis and penicillin allergy testing

…if available, is safe during pregnancy and can be beneficial for all women who report a penicillin allergy, particularly those that are suggestive of being IGE mediated, or of unknown severity, or both.



Pregnant women should undergo vaginal-rectal screening for GBS colonization at 36w0d – 37w6d (screening valid up to at least 41w0d) 

Intrapartum antibiotic prophylaxis is recommended for women

  • Who delivered a previous infant with GBS disease
  • With GBS bacteriuria in the current pregnancy
  • With a GBS-positive screening result in the current pregnancy
  • With unknown GBS status and
    • Birth <37w0d
    • Have an intrapartum temperature of ≥100.4°F (38.0°C)
    • Have rupture of membranes for ≥18 hours
  • Intrapartum NAAT result
    • Positive for GBS
    • Negative for GBS but above risk factors develop (e.g., intrapartum fever)
  • ‘Consider’ in women with positive GBS colonization in previous pregnancy and present at ≥37w0d in labor with unknown culture status in current pregnancy

Note: (1) Penicillin remains the preferred agent with ampicillin an acceptable alternative; (2) Clinicians do not need to test women who had a previous baby who developed GBS disease – These women should receive antibiotics (see above)


Q: Is the patient allergic to penicillin?  

NO – not allergic to penicillin

  • Penicillin G, 5 million units IV initial dose, then 2.5–3.0 million units every 4 hrs until delivery  or
  • Ampicillin, 2 g IV initial dose, then 1 g IV every 4 hrs until delivery

YES! – is allergic to penicillin 

Low risk for anaphylaxis: History of any of the following after receiving penicillin or a cephalosporin

  • Nonurticarial maculopapular (morbilliform) rash without systemic symptoms | Family history but no personal history | Patient reports personal history but can not recall symptoms | Pruritis but no rash | Nonspecific symptoms (e.g., nausea, diarrhea, vaginal candidiasis) that are unlikely to be allergic
    • Cefazolin, 2g IV initial dose, then 1 g IV every 8 hrs until delivery

High risk for anaphylaxis: History of any of the following after receiving penicillin or a cephalosporin

  • Suggested of IgE-mediated event: Anaphylaxis | Angioedema | Respiratory distress | Urticaria (hives) |Pruritic rash | laryngeal edema | Hypotension | Immediate flushing
  • Recurrent reactions | Reactions to multiple beta-lactam antibiotics | Positive penicillin allergy test
  • Severe non IgE-mediated reaction (T-cell mediated): Severe rare delayed-onset cutaneous or systemic reactions (e.g., Steven-Johnson syndrome)
    • DO NOT give penicillin, ampicillin or cefazolin
    • Clindamycin susceptible: Clindamycin 900 mg IV every 8 hrs until delivery
    • Isolate not clindamycin susceptible: Vancomycin 20 mg/kg every 8 hours

Note: Vancomycin: Max single dose is 2 g | Minimum infusion time of 1 hour (500 mg/30 minutes) for a dose >1 g

Risk Unknown – options include

    • Penicillin allergy testing
    • Use cephalosporin
    • Use clindamycin if isolate susceptible
    • Vancomycin if isolate not clindamycin susceptible


Possible preterm labor

  • Obtain GBS culture
    • If GBS screening performed within previous 5 weeks, that culture result should be used for management
  • Start intrapartum prophylaxis and continue through labor

Preterm labor no longer imminent

  • May stop prophylaxis and manage based on most recent GBS culture report
  • GBS culture positive
    • Do not repeat GBS screen
    • Restart prophylaxis when labor recurs
  • GBS culture negative
    • Labor recurs <5 weeks from screen: Prophylaxis not necessary
    • Labor recurs ≥5 weeks from screen: Repeat GBS screen if labor ≥36w0d – 37w6d
  • GBS status unknown
    • Administer prophylaxis if labor recurs
    • If GBS screen not done previously, obtain GBS culture before starting prophylaxis

Note: ACOG notes that there are different standards internationally: For example, RCOG recommends GBS culture 3 to 5 weeks prior to anticipated delivery date for high risk pregnancy, otherwise at 35-37 weeks gestation for uncomplicated pregnancies (see ‘Learn More – Primary Sources’ below for RCOG standards)


Obtain GBS culture and Start latency antibiotics (that cover GBS)

  • In labor
    • Continue antibiotics
  • Not in labor
    • Continue IV latency antibiotics x 48 hours, followed by 5 day oral course
      • Low risk penicillin allergy: 5 day oral with first-generation cephalosporin
      • High risk penicillin allergy: Clindamycin or azithromycin
    • GBS negative: No prophylaxis and repeat GBS culture beyond 5 week window
    • GBS positive or result unavailable: Prophylaxis when labor starts

Note: Induction recommended for PPROM ≥34w0d, although some women may wish to delay in order to enter spontaneous labor | If patient is GBS positive, expectant management should be discouraged


  • ≥4 hours of antibiotics is optimal, but no medically urgent intervention should be delayed to provide 4 hours of coverage
    • Interventions that should not be delayed when clinically indicated include: AROM | Oxytocin | Cesarean
  • Amniotomy (with appropriate GBS prophylaxis)
    • Perform as indicated
  • Membrane sweeping
    • Based on limited evidence, no association with risk
    • Some may choose to avoid this procedure in GBS positive women
  • Foley catheter
    • Small theoretical risk
    • “…no recommendation can be made either for or against timing of antibiotic prophylaxis”
  • Water immersion
    • No evidence of increased risk if appropriate GBS prophylaxis administered
    • Above assumes guidelines met that water immersion be offered to women with uncomplicated pregnancies
  • Vaginal exam (with appropriate GBS prophylaxis)
    • Perform exams as indicated
  • Intrauterine monitoring (with appropriate GBS prophylaxis)
    • Not contraindicated | Apply as indicated
  • Planned cesarean delivery, GBS culture positive and admitted in active labor
    • Single dose or combination that provides both GBS and surgical prophylaxis
    • Consider cefazolin
  • Cesarean delivery with intact membranes before labor onset
    • Intrapartum prophylaxis is not required, regardless of GBS status or gestational age
  • GBS Bacteriuria
    • No need for additional vaginal-rectal culture in 3rd trimester as intrapartum prophylaxis is indicated regardless of concentration
    • Treat bacteriuria at concentration of ≥105 CFU/mL regardless of symptoms
    • Mark sample being sent to the lab as ‘pregnant’ and especially for patients with penicillin allergy, lab should provide clindamycin susceptibility results to guide intrapartum GBS prophylaxis
    • Note: Do not use clindamycin to treat bacteriuria as it is poorly concentrated in urine (i.e., used for soft tissue/systemic infection rather than UTI)
  • Penicillin allergy testing
    • Referral to allergy or immunology specialist
    • Testing has been done in pregnancy for IgE-mediated events (some experts classify as ‘moderate risk of anaphylaxis’)
    • Delayed T-cell mediated events (e.g., a history of Steven Johnson syndrome or toxic epidermal necrolysis) is considered by some experts to be a “contraindication to standard penicillin allergy testing”

Learn More – Primary Sources:

ACOG Committee Opinion 797: Prevention of Group B Streptococcal Early-Onset Disease in Newborns

RCOG Green Top Guideline 36: Prevention of Early‐onset Neonatal Group B Streptococcal Disease