Green-top Guideline No. 36
September 2017
Universal bacteriological screening is not recommended.
Clinicians should be aware of the clinical risk factors that place women at increased risk of
having a baby with early-onset GBS (EOGBS) disease.
Should women be offered intrapartum antibiotic prophylaxis (IAP) if GBS was detected in a previous pregnancy, irrespective of carrier status this pregnancy?
Explain to women that the likelihood of maternal GBS carriage in this pregnancy is 50%.
Discuss the options of IAP, or bacteriological testing in late pregnancy and then offer of IAP if still positive.
If performed, bacteriological testing should ideally be carried out at 35–37 weeks of gestation or 3–5 weeks prior to the anticipated delivery date, e.g. 32–34 weeks of gestation for women with twins.
Should women with a previous baby affected by GBS disease be offered IAP irrespective of carrier status this pregnancy?
IAP should be offered to women with a previous baby with early- or late-onset GBS disease.
What screening tests (if any) should be offered if a woman requests testing for carrier status?
A maternal request is not an indication for bacteriological screening.
Antenatal care
Should all pregnant women be offered bacteriological screening for GBS?
Universal bacteriological screening is not recommended.
The National Screening Committee does not recommend universal bacteriological screening for GBS.
there is no clear evidence to show that testing for GBS routinely would do more good than harm.
The reasons quoted are:
Many women carry the bacteria and, in the majority of cases, their babies are born safely and without developing an infection.
Screening women late in pregnancy cannot accurately predict which babies will develop GBS infection.
No screening test is entirely accurate.
Between 17% and 25% of women who have a positive swab at 35–37 weeks of gestation will be GBS negative at delivery.
Between 5% and 7% of women who are GBS negative at 35–37 weeks of gestation will be GBS positive at delivery.
In addition, many of the babies who are severely affected from GBS infection are born prematurely, before the suggested time for screening.
Giving all carriers of GBS IAP would mean that a very large number of women would receive treatment they do not need, this may increase adverse outcomes to mother and baby
should offer IAP to women with GBS bacteriuria identified during the current
pregnancy.
Women with GBS urinary tract infection (growth of greater than 105 cfu/ml) during pregnancy should receive appropriate treatment at the time of diagnosis as well as IAP.
Antenatal treatment is not recommended for GBS cultured from a vaginal or rectal swab.
Where GBS carriage is detected incidentally or by intentional testing, women should be offered IAP.
Method of induction should not vary according to GBS carrier status.
Membrane sweeping is not contraindicated in women who are carriers of GBS.
How should planned caesarean section in women with known GBS colonisation be managed?
Antibiotic prophylaxis specific for GBS is not required for women undergoing planned caesarean section in the absence of labour and with intact membranes.
Management of term labour (including rupture of membranes) to reduce the risk of EOGBS disease.
How should rupture of membranes in a woman at term (37+0 weeks of gestation) with known or unknown GBS carrier status be managed?
Women who are known GBS carriers should be offered immediate IAP and induction of labour as soon as reasonably possible.
What are the clinical risk factors that affect the risk of GBS disease?
There are a number of clinical risk factors that appear to place women at increased risk of having a baby with EOGBS disease.
These include:
having a previous baby with GBS disease
discovery of maternal GBS carriage through bacteriological investigation during pregnancy (for example, a urine
infection or a swab taken to investigate a vaginal discharge)
preterm birth prolonged rupture of membranes suspected maternal intrapartum infection, including suspected chorioamnionitis pyrexia.
Should women be offered IAP if GBS was detected in a previous pregnancy, irrespective of carrier status this pregnancy?
Explain to women that the likelihood of maternal GBS carriage in this pregnancy is 50%.
Discuss the options of IAP, or bacteriological testing in late pregnancy and the offer of IAP if still positive.
If performed, bacteriological testing should ideally be carried out at 35–37 weeks of gestation or 3–5 weeks prior to the anticipated delivery date, e.g. 32–34 weeks of gestation for women with twins
How should labour in a woman with a temperature of 38°C or greater and without known GBS colonisation be managed?
Women who are pyrexial (38°C or greater) in labour should be offered a broad-spectrum
antibiotic regimen which should cover GBS in line with local microbiology sensitivities.
Intrapartum pyrexia (38°C or greater) is associated with a risk of EOGBS disease of 5.3 per 1000 (versus a background risk of 0.6 per 1000).
The antibiotic regimen of choice will depend on local microbiology guidance
It is recommended that 3 g intravenous benzylpenicillin be given as soon as possible after the onset of labour and 1.5 g 4 hourly until delivery.
To optimise the efficacy of IAP, the first dose should be given at least 4 hours prior to delivery.
There is evidence that benzylpenicillin levels in cord blood exceed the minimum inhibitory concentration for GBS as early as 1 hour after maternal administration.
but it is not known how this relates to neonatal colonisation or disease.
There is also evidence that giving penicillin for 2 hours before delivery reduces neonatal colonisation
but evidence suggests that 4 hours of penicillin is more effective than 2 hours at reducing the risk of EOGBS disease.
Amoxicillin is an alternative but the Cochrane review found no difference between amoxicillin and benzylpenicillin and thus, the narrower spectrum antibiotic is preferred.
intravenous amoxicillin 2 g every 6 hours (or intravenous cefuroxime 1.5 g every 6 hours in women with a nonanaphylactic reaction to penicillin) is acceptable.
Which antibiotic should be used in women with known or suspected penicillin allergy?
Provided a woman has not had severe allergy to penicillin, a cephalosporin should be used.
If
there is any evidence of severe allergy to penicillin, vancomycin should be used.
The antibiotic chosen will depend on the confidence of the diagnosis of penicillin allergy and the severity of penicillin allergy.
If the history suggests that the reaction described is not likely to be allergic in nature (e.g. vomiting only) then penicillin should be given.
If the history suggests an allergy to beta-lactams, but one that is not severe
(i.e. no anaphylaxis, angioedema, respiratory distress or urticaria), then a cephalosporin can be administered intravenously (e.g. cefuroxime, 1.5 g loading dose followed by 750 mg every 8 hours).
If the allergy to beta-lactams is severe then intravenous vancomycin (1 g every 12 hours) is recommended.
The proportion of women giving birth preterm in the UK is 8.2%.
More women present in threatened pre term labour than deliver preterm.
The risk of EOGBS disease in the infants of those women who deliver preterm is estimated to be 2.3 per 1000.
The risk of GBS infection is higher with preterm delivery and the mortality rate from infection is increased (20–30% versus 2–3% at term).
What are the appropriate swabs if testing for carrier status is to be undertaken?
When testing for GBS carrier status, a swab should be taken from the lower vagina and the anorectum.
A single swab (vagina then anorectum) or two different swabs can be used.
How quickly should the swabs be transported to the laboratory, in what medium and at
what temperature?
After collection, swabs should be placed in a non-nutrient transport medium, such as Amies or Stuart.
Specimens should be transported and processed as soon as possible. If processing is delayed, specimens should be refrigerated.
GBS isolates can remain viable in transport media for several days at room temperature. However, the recovery of isolates declines over 1–4 days, especially at elevated temperatures, which can lead to false-negative results.
How should a newborn baby be managed?
If there have been any concerns about early-onset neonatal infection, what signs should
prompt parents and carers to seek medical advice?
Parents and carers should seek urgent medical advice if they are concerned that the baby.
baby is showing abnormal behaviour (for example, inconsolable crying or listlessness), or is unusually floppy, or
has developed difficulties with feeding or with tolerating feeds, or has an abnormal temperature unexplained by environmental factors (lower than 36°C or higher than 38°C), or has rapid breathing, or has a change in skin colour
How should well babies at risk of EOGBS disease whose mothers have not received
adequate IAP be monitored?
Well babies should be evaluated at birth for clinical indicators of neonatal infection and have
their vital signs checked at 0, 1 and 2 hours, and then 2 hourly until 12 hours.
Two studies have shown that 90% of infants who are diagnosed with early-onset infection will display signs by 12 hours.
How should a baby with clinical signs of EOGBS disease be managed?
Babies with clinical signs of EOGBS disease should be treated with penicillin and gentamicin
within an hour of the decision to treat.
How should the baby of a mother who has had a previous baby with GBS disease be
managed?
Babies should be evaluated at birth for clinical indicators of neonatal infection and have their
vital signs checked at 0, 1 and 2 hours, and then 2 hourly until 12 hours.
Mothers who have had a previous baby with GBS disease will be offered IAP. Following careful clinical assessment the baby’s vital signs and clinical condition should be monitored closely for at least 12 hours (see NICE clinical guideline 149) Evidence level 4
Although some clinicians prefer to obtain blood cultures and treat the baby with intravenous penicillin, and then stop the antibiotics at 36 hours if the cultures are negative, there is no evidence that this is necessary
What advice should be given to women regarding breastfeeding?
Breastfeeding should be encouraged irrespective of GBS status.
Pathway of care
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