ABSTRACT
The objective of this paper is to evaluate the effect of different prevention strategies
on the rate of early-onset neonatal group B streptococcus (GBS) disease and mortality.
We compared the neonatal mortality and morbidity rates associated with early-onset
GBS disease in three periods characterized by different prevention strategies, including
no screening for GBS during pregnancy and no standardized chemoprophylaxis (1/1987
to 12/1990), antibiotic prophylaxis only with risk factors for GBS (1/1991 to 12/1994),
and universal screening for GBS with rectovaginal cultures and chemoprophylaxis for
women with positive results or risk factors (1/1995 to 12/1999). Statistical analysis
included Fisher's exact test and Chi-square, with a two-tailed p <0.05 considered significant. The yearly prevalence of positive GBS cultures was
similar throughout the screening period (mean 18%, range 16 to 19%). Compared with
the no prophylaxis group (rate = 4/8,573), introduction of universal screening (rate
= 0/13,754, p = 0.02) but not of prophylaxis for risk factors alone (rate = 1/10,303, p = 0.18) significantly decreased the occurrence of GBS-specific neonatal mortality.
Universal screening decreased, though not significantly, the GBS-specific neonatal
morbidity rates compared with a policy based on risk factors alone (0.4/1000 vs. 0.8/1000,
p = 0.29). Our study had a power to detect a 0.7/1000 difference in the rate of specific
morbidity between the two chemoprophylaxis policies (α = 0.05, β= 0.80). Intrapartum
prophylaxis for GBS, using universal screening or risk factors, is associated with
a significant reduction in the specific neonatal mortality rate compared with no prophylaxis.
Universal screening for GBS leads to a decrease in specific GBS morbidity compared
with screening using risk factors alone.
KEYWORDS
Group B streptococcus - neonatal sepsis - antibiotic prophylaxis - screening - risk-based
approach
