Group B Streptococcal Disease in Neonates

1. Group B Streptococcal Disease in Neonates Michael Addidle Clinical Microbiologist

2. Neonatal Group B Infection • Bi-modal distribution • Early onset – First 7 days, mean 12 hrs • Late onset- 7days to 3 months, mean 3 weeks. • Higher attack rates in premature babies • 50% of babies born to colonised mothers acquire the organism. 1-2% of those will become ill from it.

3. Early Onset Group B Strep Disease • Approx 1-2 per 1000 births • Septicaemia 80% • Pneumonia 10% • Meningitis 10% • Mortality 5-10%, inversely proportional to birthweight. • Irritability, lethargy, tachypnoea, grunting, hypoxia, temp. instability, hypotension and poor perfusion. • Fever is uncommon in first 24 hrs. • WCC may be low, normal or high

4. Strategies to prevent Early Onset neonatal Group B Streptococcus Infection • Universal based screening strategy. (US policy) Screen all pregnant women at 35-37 weeks gestation with a recto-vaginal swab, then giving all those positive for Group B Streps intra-partum antibiotics. • Risk factor based approach. (UK and NZ policy) • Previous infant with GBS disease • GBS bacteriuria during this pregnancy • Pre-term labour <37 weeks • Prolonged rupture of membranes (>18hrs) • Intra-partum fever >38C Funding and lack of evidence Compliance

5. Intra-partum antibiotics • Note that antenatal antibiotics not shown to have benefit for vaginal colonisation with Group B streptococci. • 1.2g IV Benzyl penicillin initially and then 0.6g 4 hrly during labour. • If penicillin allergic (and no history of anaphylaxis), cephazolin 2g initially then 1g 8hrly • If prior anaphylactic reaction to penicillin the either vancomycin 1g 12 hrly, or clindamycin 600mg 8hrly are indicated. (NZ guidelines recommend vancomycin but clindamycin is fine if Gp B strep isolated and known to be susceptible.) • This will decrease incidence of invasive disease in newborn by approx 90%, most effective if abx started more than 4 hrsbefore delivery. • If maternal chorio-amnionitis (intra-partum fever with two of the following signs: foetal tachycardia, uterine tenderness, offensive vaginal discharge or increased maternal WCC) then penicillin alone is insufficient. Broad spectrum abx required egAmoxycillinclavulanate

6. Strategies to prevent neonatal Group B Streptococcus Infection • Incidence of Group B neonatal disease slightly lower in screening based approach (0.33 v 0.59 per 1000 live births respectively) • No discernible effect on mortality • UK (and NZ) believe that screening approach is not cost-effective.

7. Strategies to prevent neonatal Group B Streptococcus Infection in New Zealand • Grimwood K, Darlow BA, Gosling IA, et al. Early-onset neonatal group B streptococcal infections in New Zealand, 1998-1999. J Paediatr Child Health. 2002;38:272–7. • 0.5 cases per 1000 live births. • 60% of these cases had risk factors but had not received intra-partum antibiotics. • Journal of the New Zealand Medical Association, 20-August-2004, Vol 117 No 1200 The prevention of early-onset neonatal group B streptococcus infection: technical report from the New Zealand GBS Consensus Working Party.

8. Downside of GBS prevention strategies • Risk of serious anaphylactic reaction to penicillin is 1 in 10,000 and of a fatal reaction 1 in 100,000. • Increased resistance to Group B streptococci. Anecdotal evidence for lincosamides in particular. • Theoretical possibility of increased non-GBS infection eg E.coli has not been backed up by the majority of evidence however.

9. Summary • Neonatal Group B streptococcal disease remains an important cause of morbidity and mortality. • No strategy will prevent all early-onset neonatal GBS disease. • Compliance is key to a risk factor based approach. • Regular audit of above is recommended to ensure compliance. Audit of the 5 main risk factors is straightforward. • Recognition of the signs of sepsis and early treatment of affected babies is just as important. • Questions?