Group B Strep – Prophylaxis and Treatment in Neonates

Background:

 

GBS septicaemia is the commonest cause of early onset sepsis in the neonatal period. The incidence is 0.5/1000 births in the UK & Ireland. The mortality from Early-Onset Group B Strep Disease (EOGBSD) in the UK is 6% (2-3% for term infants and 18% for preterm infants. The carriage rate of GBS in pregnant women is between 25-33% and in the absence of any intervention approximately 1% of babies born vaginally to these women develop EOGBSD. The predisposing factors to the development of disease include – intrapartum pyrexia, prematurity, PROM (>18-24hrs), chorioamnionitis, previous affected sibling, GBS bacteriuria (104 colony count) and incidental GBS carriage in present pregnancy.

 

Prevention of vertical transmission of EOGBSD has been achieved through the administration of Intrapartum antibiotic prophylaxis (IAP) using Penicillin or Cefazolin /Clindamycin (for women allergic to Penicillin). Identification of eligible women had traditionally employed two approaches – bacteriological screening (at 35-37wks) and risk-based approach. A third approach advocated by the Canadian authorities is a combination of the two approaches. The bacteriological approach is said to be superior to the risk-based approach with reduction of the incidence of EOGBSD by 86% and 50-68.8% respectively. The third approach leads to an incidence reduction of 51%. However, the number of women given IAP is 31.7% with bacteriological screening, 25% with the risk-based approach and 3.4% with the Canadian option. Despite concerns about emerging resistance, GBS continue to be susceptible to Penicillin, although isolates with increased minimum inhibitory concentration (MIC) to the drug has been reported. Increase in the number of early-onset neonatal sepsis caused by Gram-negative bacteria has been reported but the trend is not consistent. Maternal anaphylaxis associated with GBS IAP occurs but is sufficiently rare.

 

Vertical transmission prevention practices vary widely in the UK and there is currently no national screening programme. However, best-practice guidelines by the RCOG, Health protection agency (HPA), GBS support group (GBSS) are available. The Centre for Disease Control (CDC) has published a new and revised guideline for prevention of EOGBSD in November 2010. This guideline is derived from a literature review of the above documents.

Antenatal GBS Fact-sheet:

  1. Routine screening (either bacteriological or risk-based) for antenatal GBS carriage is not recommended by the RCOG in the UK.
  2. If bacteriological swabs need to be taken for clinical reasons this should include a combined low vaginal and rectal swab. GBS detected on HVS and non selective media increases the risk of transmission to the neonate.
  3. IAP does not prevent late-onset GBS disease
  4. If GBS is detected incidentally, antenatal treatment with oral Penicillin is not recommended as it does not reduce the likelihood of GBS colonisation at the time of delivery.
  5. IAP should be considered if GBS is detected incidentally
  6. IAP should be offered to women with GBS bacteriuria who should also be treated appropriately at the time of diagnosis
  7. IAP should be offered to women with a previous baby with neonatal GBS disease
  8. EOGBSD risk is increased if GBS is isolated from a HVS and non-enriched medium but reduced if obtained at an earlier stage of pregnancy
  9. Where GBS carriage status in the current pregnancy is unknown, there is no good evidence to support the use of routine IAP in women solely based on  GBS carriage in previous pregnancy
  10. In the absence of labour  in women with intact membranes  undergoing elective C/S,  IAP is not needed regardless of their GBS colonisation status
  11. If started, specific GBS prophylaxis should be discontinued within 48 hours in women with preterm ROM, unless they are in established labour

 

Delivery care:

  1. Broad spectrum antibiotic including an agent active against GBS should be given in place of IAP if chorioamnionitis is suspected
  2. Women with other risk factors – Intrapartum pyrexia (Fever>380C once or >37.50C on two occasions taken 2 hours apart), prematurity, PROM (>24hrs),  should be considered for IAP especially in the presence of two or more factors
  3. Penicillin or / Clindamycin as appropriate (in Penicillin allergy) should be given as soon as labour is established. To optimise the efficacy of IAP, the first dose should be given at least 4 hours prior to delivery – ‘Adequate IAP’.
    • Penicillin G – 3g (5 Megaunits) IV stat, then 1.5g (2.5Megaunits) 4hrly until delivery
    • In Penicillin allergic patients – guided by specific requests for antibiotic sensitivity
    • Clindamycin – 900mg IV 8hrly until delivery

 

Neonatal Care for infants at risk of EOGBS infection:

  1. Infants with signs of sepsis – whether term or preterm should be admitted to the NICU, undergo full septic screen (Blood culture, FBC, CRP, Chest X-ray and lumbar puncture) and   treated promptly with antibiotics.
  2. Infants born to mothers with frank chorioamnionitis should undergo partial septic screen and intravenous antibiotic therapy as per neonatal guidelines irrespective of gestation and IAP status, Need for further investigations should be guided by clinical progress and initial results.
  3. Well appearing term infants without risk factors and adequate IAP (Low risk) do not need laboratory evaluations and postnatal antibiotic treatment. They should be observed for 24 hours in hospital.
  4. Well appearing preterm infants of 35-36 weeks gestation without additional risk factors who received adequate IAP should be observed in hospital for at least 48 hours without the need for any laboratory evaluation.
  5. Well appearing term infants with an indication for GBS prophylaxis who received no / inadequate IAP may be observed clinically in hospital for 24 hours without intervention if they have no additional risk factors
  6. Well term infant with multiple risk factors irrespective of IAP status should undergo partial septic screen (Blood culture, FBC, CRP) and presumptively treated with antibiotics for 36 hours until culture results are known (Pragmatic decision)
  7. Preterm infants of 35-36 weeks gestation with no or inadequate IAP or those with additional risk factors irrespective of IAP status should undergo partial septic screen and treated presumptively with antibiotics for 36 hours pending culture results.
  8. In infants with previous GBS affected sibling, observe for 24hrs if adequate IAP was given. If IAP inadequate or additional risk factors perform partial septic screen and commence post-natal antibiotics
  9. Treat all infants of multiple pregnancies if one is diagnosed or suspected with possible GBS disease.
  10. Surface swab is not warranted in the neonatal preventive strategy for EOGBSD as they are not indicators of infection.
  11. Mothers with known GBS colonisation who refuse intrapartum antibiotics should be advised hospital based observation of the neonate for 24 hours irrespective of her choice of place of delivery. This should be documented in the clinical notes.

 

Use the following flow chart to decide if the baby needs antibiotics treatment –

Sepsis Prophylaxis Flow-chart – for early onset infection.pdf

 

The following observation schedule should be observed in all babies on the sepsis prophylaxis pathway

Observe for first 12 hours at 1hour, 2hour and 2 hourly for 10 hours. Thereafter observations should continue 4 hourly if indicated.

  • General well being
  • Chest movements and nasal flare
  • Skin colour (Test capillary refill – <2 sec)
  • Feeding
  • Muscle tone
  • Temperature (Normally 36-37C)
  • Respiration ( Normally 30-60 breaths/min)
  • Heart rate if any of the above abnormal (Normally 100-160/min

 

Follow up:

  1. When a baby who has had a confirmed GBS infection is discharged from hospital
  • advise the woman that if she becomes pregnant again:
  • there will be an increased risk of early-onset neonatal infection
  • she should inform her maternity care team that a previous baby has had a GBS infection
  • antibiotics in labour will be recommended
  • inform the woman’s GP in writing that there is a risk of:
    • recurrence of GBS infection in the baby, and
    • GBS infection in babies in future pregnancies.
  1. If the woman has had group B streptococcal colonisation in the pregnancy but without infection in the baby, inform her that if she becomes pregnant again, this will not affect the management of the birth in the next pregnancy.