[CG] Group B Streptococcal prophylaxis, obstetric guideline

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Audience

This guideline is applicable to all medical, nursing in midwifery staff caring for women and neonates in Greater Glasgow & Clyde. Staff should also be familiar with the relevant drug monographs.

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Introduction

Group B streptococcus is the commonest cause of early onset infection in the neonatal period. The organism frequently colonises the lower vagina or anorectum and may pass to the baby following rupture of the membranes, or occasionally prior to membrane rupture in the presence of amnionitis. This guideline aims to interrupt the transmission of GBS by giving intrapartum antibiotic prophylaxis to the mother. Two approaches have been used to identify mothers who should be offered intrapartum antibiotic prophylaxis. Mothers may be identified through routine bacteriological screening during the pregnancy or based on clinical risk factors for transmission of the organism. In the UK the Royal College of Obstetricians recommends the latter approach.

In 2012, NICE published guidance on antibiotics for the prevention and treatment of early onset neonatal infection (NICE CG149). This includes advice on maternal risk factors which warrant the use of intrapartum antibiotic prophylaxis. It also includes advice on the management of babies born to mothers with intrapartum risk factors, or where there are abnormal signs or symptoms in the baby, indicating an increased risk of early onset infection (including with Group B Streptococcus). All such babies are monitored using a Neonatal Early Warning Screening (NEWS) chart and some will receive antibiotics if there are multiple risk factors, signs or symptoms, or any single “red flag” risk factor, sign or symptom. This is all detailed in the neonatal Early Onset Sepsis (EOS) guideline.

Antenatal care

All pregnant women should be provided with an appropriate information leaflet regarding GBS.

Universal bacteriological screening is not recommended. A maternal request for screening is not an indication, but should be discussed with healthcare professionals on an individual basis.

Antenatal treatment is not recommended for GBS cultured from a vaginal or rectal swab. Women with GBS urinary tract infection (> 10cfu/ml) during pregnancy should receive appropriate treatment at the time of diagnosis, as well as intrapartum antibiotic prophylaxis.

Intrapartum antibiotic prophylaxis (IAP)

1– Prophylaxis cases

The following groups of women should be offered IAP with an intravenous antibiotic which is effective against GBS. This will be benzylpenicillin or, for penicillin sensitive women, teicoplanin.

  • Women in whom colonisation with GBS has been identified in current or previous pregnancy
  • Women with GBS bacteriuria in current or previous pregnancy
  • Women with previous baby affected by early- or late-onset neonatal GBS disease
  • Women in confirmed preterm labour< 37+0 weeks gestation

Women with GBS detected in a previous pregnancy have a 50% risk of recurrent GBS carriage and should be offered routine IAP or the option of bacteriological testing in late pregnancy, followed by IAP if still positive.

If performed, bacteriological testing should be carried out at 35-37 weeks gestation or 3-5 weeks prior to the anticipated delivery date, i.e. 32-34 weeks gestation in multiple pregnancies. A single (Amies charcoal) swab should be taken from the lower vagina and anorectum. Healthcare professionals should indicate that the swab is being taken for GBS.

2– Potentially infected women who require antibiotics that also cover GBS

In women:

  • Where chorioamnionitis is suspected
  • Who have a pyrexia during labour (> 38°C) or a temperature of ≥ 37.5°C on 2 separate occasions at least 2 hours apart or maternal sepsis with a temperature < 36°C
  • For whom the sepsis 6 bundle is triggered

Antibiotic therapy should be according to GGC guidelines but in addition, must include specific GBS prophylaxis as below.

Intrapartum prophylaxis

(to start at the onset of labour)

Benzylpenicillin 3 g IV loading infusion over 30 minutes followed every 4 hours by 1.8 g IV infusion over 30 minutes until delivery. For women who have a genuine allergy to penicillin, give Teicoplanin 12 mg/kg * over 3-5 minutes as a slow IV bolus or over 30 minutes by IV infusion every 12 hours until delivery. (See Appendix 1)

* based on most recent body weight – round each dose to nearest 100 mg (max 800 mg)

Antibiotic therapy for women with suspected chorioamnionitis, intrapartum pyrexia or sepsis should be reviewed at delivery and/or after a maximum of 48 hours.

Clinicians should be aware of the potential adverse effects of IAP including anaphylaxis.

 

Effective prophylaxis

Prophylaxis is more effective if the first dose is given at least 4 hours prior to delivery and continued at the correct intervals. Antibiotics should be started as soon as possible after the onset of labour and continued until delivery. Prophylaxis is considered to have lapsed if a dose is more than 1 hour late. If prophylaxis with benzylpenicillin has lapsed a 3g loading dose is required rather than the routine 1.8g dose.

NB – As the primary goal of IAP is to prevent transmission of GBS to the neonate, it is vital to give effective prophylaxis even if the baby will receive antibiotics after delivery due to the presence of other risk factors for early onset sepsis.

Women who are receiving prophylactic antibiotics for GBS in labour who require a caesarean section will still require routine co-amoxiclav or clindamycin cover  (See antibiotic guideline).

Irrespective of gestation and the presence of risk factors for GBS transmission, IAP is not required if delivery is by planned caesarean section with intact membranes and the baby is clinically well.

 

Management of rupture of membranes to reduce the risk of GBS transmission

Women with rupture of membranes at term (≥ 37+0 weeks gestation) who are known GBS carriers should be offered immediate IAP and induction of labour as soon as reasonably possible.

Bacteriological testing for GBS carriage is not recommended for women with preterm prelabour rupture of membranes. IAP should be given once labour is confirmed or induced irrespective of GBS status. However, known GBS colonisation should be taken into consideration when making decisions about timing of delivery in women with preterm prelabour rupture of membranes. For those at more than 34+0 weeks of gestation it may be beneficial to expedite delivery if the woman is a known GBS carrier.

Communication

It  will  be  the  responsibility  of  the  labour ward  staff  to  communicate  to  the neonatologist  the following information:

  • That risk factors for early onset neonatal GBS disease have been identified
  • Whether prophylaxis has been started and, if so, how long prior to delivery
  • Whether there is evidence of maternal sepsis

The requirement for prophylaxis should be recorded on the alert area in the maternal notes.
Remember if mother is septic ensure neonatologist informed.

Frequently asked questions (FAQ)

Parents who decline intrapartum antibiotic prophylaxis or empirical treatment for their baby

We recommend GBS prophylaxis. Intrapartum prophylaxis may be declined despite this advice. Empirical therapy for well infants born to mothers with risk factors may also be declined.

If parents decline these interventions the medical staff should ensure that they are aware of the level of risk of early onset GBS disease and the life threatening nature of GBS sepsis. The infant should remain in hospital for at least 24 hours and observations of temperature, pulse and respiratory rate performed 3 hourly and recorded on a NEWS chart.

GBS prophylaxis is offered by maternity staff to the mother and this must be adequately explained. If the clinician is unable to answer any queries then a relevant professional should be asked to address any concerns. This should conclude with a decision as to whether prophylaxis is accepted or declined and this must be clearly documented.

When prophylaxis or empirical treatment is declined by informed parents, this should be documented. It is not appropriate to suggest or instigate child protection proceedings.

The baby should be monitored on a NEWS chart and treated with antibiotics if abnormal clinical signs or symptoms are identified (refer to EOS guideline for details). Parents may not decline therapy for their baby if signs or symptoms of infection are present.

Appendix 1 Teicoplanin Dose Banding for GBS Prophylaxis

  Most recent weight   Dose (mg)
  Less than 36 kg   400mg
  36 - 45.9 kg   500mg
  46 - 53.9 kg   600mg
  54 - 61.9 kg   700mg
  62 kg or above   800mg
References

RCOG. Prevention of early-onset neonatal group B streptococcal disease. [Green-top Guideline No 36] September 2017.

NICE. Antibiotics for early-onset neonatal infection. [CG149] August 2012.

Last reviewed: 19 February 2019

Next review: 01 December 2023

Author(s): Dr Andrew Brown (ST6), Dr Ann Duncan (Consultant Obstetrician), Dr Brian Jones

Approved By: Clinical Governance