GBS

Question 1

What are the 2 ways of deciding who gets GBS prophylaxis in labour

Answer 1

Universal culture-based screening, using combined low vaginal plus or minus
anorectal swab at 35-37 weeks gestation, or a clinical-risk factor based
approach are both acceptable strategies for reducing EOGBS.

Question 2

What is the leading cause of neonatal sepsis?
How many woman are carriers of GBS?
What is the rate of EOGBS?
What is the associated fatality?

Answer 2

GBS

15-25% of woman are asymptomatic carriers
Less then 30% of babies are colonised
0.5-0.25% risk of GBS

Fatality for EOGBS is 14%
Term 2-3%
preterm 20-30%

Question 3

How does EOGBS present

How does LOGBS present

Answer 3

EOGBS
Respiratory symptoms + pneumonia

Preterm infants are 4X more likely to develop GBS
LOGBS
1 week to 3 months
Meningitis and septicaemia

Question 4

How Intrapartum ABs reduce the risk of EOGBS?

By how much?

Answer 4

risk is reduced by 80%
No change to late onset
It is cost effective

Declining prevalence with this approach

Question 5

What are the risk factors for EOGBS

Answer 5

Clinical risk factors for EOGBS include:
 Spontaneous onset of labour at ≤ 37 weeks gestation.
 Rupture of membrane ≥ 18 hours.
 Maternal fever over 38C.
 A previous infant with EOGBS.
 GBS bacteruria during the current pregnancy.
 Known carriage of GBS in current pregnancy.
 Clinical diagnosis of chorioamnionitis
 Other twin with current EOGBS.

Question 6

How to perform culture based screening for GBS colonisation?

When is the timing most accurate?

Answer 6

The culture needs to be performed on a elective enriched media in order improve the sensitivity. False negative rates of up to 50% can occur without the use of enriched culture media. Rectovaginal culture at 36 weeks has a sensitivity of 91% and specificity of 88.9% for intrapartum maternal vaginal colonization.

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.

Less accurate after 5 week
Best 35-37 weeks

Question 7

What does GBS bacturia represent

Answer 7

Heavy colonisation therefore IAP is indicated

Question 8

What antibiotics should be used?

What AB timing is optimal?

Answer 8

Intravenous penicillin and ampicillin are equally effective against GBS, but penicillin may be preferable for IAP because of its narrower spectrum of activity.

Optimal IAP is defined as penicillin administered at least four hours prior to delivery. Appropriate doses for intrapartum penicillin should be in line with institutional/jurisdictional protocols

Question 9

What is the risk of anaphylaxis to B lactam if no allergy history

Answer 9

Penicillin administered to a woman with no known history of blactam allergy carries a risk of anaphylaxis of between 4/10,000 to 4/100,000.

Question 10

How to manage penicillin allergy with GBS testing?

Answer 10

Women with known penicillin allergy should have sensitivity testing for clindamycin and
erythromycin specifically requested at the time of GBS culture. Approximately 20% of GBS strains will be resistant to clindamycin, and 30% to erythromycin. For those women allergic to penicillin,
alternative antimicrobial strategies should be used in accordance with local
institutional/jurisdictional guidelines.

Question 11

If a woman has allergy / anaphylaxis to penicillin what are the treatment options?

Answer 11

Women who have not experienced anaphylaxis, angioedema, urticarial, or respiratory distress after a penicillin or cephalosporin can receive IV cefazolin for IAP.

For woman at risk of anaphylaxis with penicillin, and where the GBS is resistant to erythromycin or clindamycin, vancomycin is the recommended alternative with a dosage regime of 20 mg/kg
intravenous every 8 hours (to a maximum individual dose of 2 grams).

Question 12

Do woman need IAP if they are having an ELLSCS?

What if she ROM be LSCS?

Answer 12

For elective Caesarean section prior to the onset of labour, no additional prophylaxis is
recommended, irrespective of GBS carriage.
However, if a woman screened positive for GBS commences labour or has spontaneous rupture of the membranes before her planned CS, she
should receive IAP while awaiting delivery.

Question 13

What is the RANZCOG position on vaginal seeding and GBS woman?

Answer 13

The safety of “vaginal seeding” at elective CS (a practice where maternal vaginal microbes are
transferred to the newborn by wiping his/her face with a gauze swab that has been incubated in the
mother’s vagina) in the presence of maternal GBS carriage is unknown. Given the unproven
benefits of this practice for infant immune system development, and the potential risk of early or late
onset GBS disease as a consequence of infant colonisation, vaginal seeding should not be
performed in GBS positive women.

Question 14

Women with preterm labour, GBS status unknown

What do you do?

Answer 14

Women who present with threatened preterm labour should have a rectovaginal swab taken for
GBS culture. IAP for GBS should be commenced if labour establishes and continued until delivery.
If labour does not establish, GBS prophylaxis should be ceased. If the culture is subsequently found
to be positive IAP should be recommenced at the time of labour onset.

Question 15

If Term and ROM + GBS not in labour

If term ROM and unknown status ?

Answer 15

IOL straight away

GtG
In women where the carrier status is negative or unknown, offer induction of labour immediately or expectant management up to 24 hours. Beyond 24 hours, induction of labour is appropriate.

Question 16

PPROM

Answer 16

For women with suspected or confirmed PPROM a rectovaginal swab should be taken for GBS culture. In this setting there is insufficient evidence to provide conclusive recommendations and in
North America the CDC and ACOG recommend that IAP should be given for 48 hours, or until a negative GBS result is returned, whereas in the UK setting the RCOG does not support this.
If the GBS result is subsequently found to be positive then IAP should be offered with the onset of
labour. Antibiotics for latency (that is, to lengthen gestation) should be given independent
consideration to GBS prophylaxis.

Gtg 2018
For those with evidence of colonisation in the current pregnancy or in previous pregnancies, the perinatal risks associated with preterm delivery at less than 34 +0 weeks of gestation are likely to outweigh the risk of perinatal infection. For those at more than 34 +0 weeks of gestation it may be beneficial to expedite delivery if a woman is a known GBS carrier

Question 17

RCOG guidance - if GBS colonised in previous pregnancy

how to manage this pregnancy?

Answer 17

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.

Question 18

How do you manage GBS Colonised woman who declined IAP?

Answer 18

Women with known GBS colonisation who decline IAP should be advised that the baby should be very closely monitored for 12 hours after birth, and discouraged from seeking very early discharge from the maternity hospital.

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.

Question 19

Should babies get prophylaxis?

Answer 19

Postnatal antibiotic prophylaxis is not recommended for asymptomatic term infants without known antenatal risk factors.

Question 20

How should a baby with clinical signs of EOGBS disease be managed?

Answer 20

Babies with clinical signs of EOGBS disease should be treated with penicillin and gentamicin within an hour of the decision to treat.

Question 21

If a woman has had a previous EOGBS baby - how should her next baby be managed?

Answer 21

IAP
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.

Question 22

What is the argument for NOT screening everyone?

- this is from RCOG

Answer 22

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 (see sections below).

Question 23

What culture medium is used for GBS testing?

Answer 23

The most widely used enriched culture medium is Todd‐Hewitt broth with nalidixic acid and colistin (e.g. Lim broth), or nalidixic acid and gentamicin further subcultured on a blood agar plate. Several options are available for the subculture of an enriched culture medium for isolation of GBS, including selective and chromogenic aga