Epidemiology and predictive values of risk factors for neonatal group B streptococcal sepsis.
OBJECTIVE
To determine the incidence of and factors affecting risk factors for neonatal group B streptococcal (GBS) sepsis and their predictive values for intrapartum GBS carriage; to calculate the proportions of women eligible for intrapartum antibiotic prophylaxis (IAP) using different selection protocols.


METHODS
Cohort study.


METHODS
Antenatal clinics and labour wards of a community hospital and a tertiary referral centre in western Sydney


METHODS
Women attending antenatal clinics during the study periods were invited to participate.


METHODS
Approximately 500 women attending antenatal clinics were screened for GBS carriage at 26-32 weeks gestation and at delivery, using several screening methods. Clinical risk factors for neonatal sepsis were recorded during labour.


METHODS
Incidence of antenatal anovaginal GBS carriage and clinical risk factors during labour, their predictive values for intra-partum GBS carriage and their relationship, if any, to demographic and obstetric factors.


RESULTS
Antenatal and intra-partum GBS carriage rates were similar but varied from 18% to 27%, depending on screening methods. The best positive and negative predictive values of antenatal GBS culture, for intra-partum carriage, were 69% (95% confidence interval (CI) 64-74) and 92% (95% CI 50-94) respectively Clinical risk factors occurred in similar proportions of GBS carriers and non-carriers.


CONCLUSIONS
Neither early antenatal screening nor clinical risk factors are reliable predictors of intra-partum GBS carriage. Intra-partum antibiotic prophylaxis based on GBS carriage or risk factors when carrier status is unknown would involve approximately 35% of women, compared with approximately 16% if based on risk factors only Both strategies would prevent similar proportions of neonatal deaths from GBS sepsis. Compliance with a preventive protocol is the most likely determinant of its overall effectiveness.
Gilbert
G L
GL
Centre for Infectious Diseases and Microbiology Laboratory Service, Westmead Hospital, University of Sydney, Sydney, New South Wales, Australia.
Hewitt
M C
MC
Turner
C M
CM
Leeder
S R
SR
D000328:Adult; D019072:Antibiotic Prophylaxis; D002353:Carrier State / Q000175:diagnosis; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D015997:Neonatal Screening / Q000379:methods; D011237:Predictive Value of Tests; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000175:diagnosis* / Q000517:prevention & control; D011296:Prenatal Diagnosis / Q000379:methods; D012189:Retrospective Studies; D012307:Risk Factors; D018805:Sepsis / Q000151:congenital / Q000453:epidemiology* / Q000517:prevention & control; D013290:Streptococcal Infections / Q000151:congenital* / Q000175:diagnosis* / Q000453:epidemiology* / Q000517:prevention & control; D013292:Streptococcus agalactiae