Background: Group B streptococcus is a leading cause of neonatal bacterial infections. Despite adoption of preventive strategies, cases of infection continue to occur and there is concern that widespread antimicrobial prophylaxis might delay rather than prevent disease onset, increasing the rates of late-onset diseases.
Objectives: The purpose of this study was to determine the incidence and clinical features of early- and late-onset group B streptococcus disease in a northern region of Italy where a screening-based approach had been proposed.
Methods: A population-based study was prospectively conducted in Emilia-Romagna, Italy. Infections that occurred during 2003-2005 in infants aged <3 months were analyzed.
Results: Among 112,933 live births, 56 cases of invasive disease (30 early- and 26 late-onset disease) were observed, giving an annual group B streptococcus disease incidence of 0.50 per 1000 live births. Eleven infants with early-onset disease showed no signs of illness or were mildly ill, whereas 19 had moderate-to-severe symptoms, and culture-proven meningitis was found in 2. Risk factors were detected in 12 women. Twenty-two mothers had antenatal screening; 5 were group B streptococcus colonized, but 17 were culture-negative. Prophylaxis was administered in 3 women. Three infants with late-onset diseases were mildly ill, whereas 23 had moderate-to-severe symptoms. Risk factors were found in 7 mothers. Late-onset diseases were clinically more severe than early-onset diseases; meningitis was diagnosed in 12 infants, and 4 of 26 died.
Conclusions: The incidence of early-onset disease was low. Some early infections were still observed because of negative screening results or missed opportunity for prevention. Late-onset diseases accounted for most meningitis cases and deaths. Strict adherence to protocols and adoption of optimal culture methods would further improve prevention of early-onset disease, but the aim of future strategies should be the prevention of all invasive diseases.