Background: The estimated incidence of true early-onset group B streptococcal (GBS) neonatal infection is based on positive GBS blood or cerebrospinal fluid (CSF) culture results, but the real burden of disease is underestimated owing to the high incidence of culture-negative sepsis possibly because of antibiotic administration to the mother.
Objective: To examine the rate of probable early-onset GBS neonatal sepsis and to assess its impact on total GBS neonatal disease.
Design: A multicentre longitudinal prospective surveillance of 107,021 deliveries.
Results: The rates of culture-proven and probable early-onset GBS sepsis were 0.39 and 0.47 per 1000 live births, respectively. Of great concern was the finding of three deaths related to the infection in the group with probable early-onset GBS sepsis.
Conclusions: The use of chemoprophylaxis in GBS-colonised pregnant women, especially when it is incomplete, may not be sufficient to prevent clinical neonatal infection, but may inhibit the growth of GBS in blood and CSF cultures. In assessing the effectiveness of GBS prophylaxis, it is advisable to consider the incidence of culture-positive and probable culture-negative GBS neonatal infection.