8A) Antenatal Care: Group B Streptococcus Flashcards
Type of organism Group B Streptococcus (6 facts)
- Gram positive coccus bacteria
- Forms chains
- Catalase negative
- Facultative anaerobe
- Lancefield group B
- Beta-haemolytic
Real name Group B Streptococcus
Streptococcus agalactiae
Incidence of GBS carriage at delivery (overall, with previous colonisation, if test at 36 weeks positive, if test at 36 weeks negative)
Overall carriage rate: 20-40%
Previous GBS colonisation: 50%
+ve test at 36/40: 75%
-ve test at 36/40: 5%
Ethnicity with highest and lowest GBS carriage
Highest: Black African
Lowest: SE Asian
Risk factors for developing early-onset GBS disease (EOGBS)
- Previous EOGBS
- Known GBS colonisation
- Preterm labour
- PROM
- Pyrexia in labour
- Suspected maternal infection
Incidence of EOGBS (overall, with previous colonisation, if test at 36 weeks positive, if test at 36 weeks negative, if colonisation known and IAP given, preterm labour, pyrexia in labour)
Overall risk: 1 in 1750 Previous GBS colonisation: 1 in 800 \+ve test at 36/40: 1 in 400 \+ve test and receive IAP: 1 in 4000 -ve test at 36/40: 1 in 5000 Preterm labour: 2 in 1000 Pyrexia in labour: 5 in 1000
Mortality and disability associated with EOGBS
7.5% disability
5% mortality
Intrapartum antibiotic prophylaxis regime
- 3 gram benzylpenicillin loading dose and then 1.5gram 4 hourly until delivery
Penicillin allergy:
- 1.5 gram cefuroxime loading dose and then 750mg TDS
- Vancomycin 1 gram BD
Management of patient with GBS colonisation in previous pregnancy
Offer either testing at 35-37 weeks or IAP.
Management of patient with GBS disease in previous pregnancy
Offer IAP
Management of patient with GBS on urine sample in this pregnancy
Treat UTI and offer IAP
Management of patient with GBS on vaginal/rectal swab in this pregnancy
Offer IAP
Management of patient with rupture of membranes:
- Term and known GBS
- Term and GBS status unknown/negative
- Preterm and known GBS
- Preterm and GBS status unknown/negative
- Term and known GBS: Offer immediate augmentation and IAP.
- Term and GBS status unknown/negative: Offer augmentation after 24 hours.
- Preterm and known GBS: Erythromycin, offer augmentation and IAP from 34/40.
- Preterm and GBS status unknown/negative: Erytromycin and IAP once in labour
Management of pyrexia in labour
Broad spectrum antibiotics e.g. amoxicillin 2 gram QDS or cefuroxime 1.5gram QDS
Management of baby at risk of EOGBS
- Term + IAP: No special considerations
- Risk of EOGS and no IAP: Obs 1 hourly until 2 hours and then 2 hourly until 12 hours
- Clinical signs of EOGBS: Penicillin + gentamicin within 1 hour
- Previous EOGBS: Obs 1 hourly until 2 hours and then 2 hourly until 12 hours.