Group B streptococcal disease in portuguese infants younger than 90 days

Abstract

Group B Streptococcus (GBS) is the most common isolate in mother-related infection in newborns.

Aims: To evaluate the epidemiology of GBS infection in the first 90 days after birth; to determine if prophylaxis for early-onset neonatal GBS infection can be based only on risk factors.

Design: National epidemiologic surveillance.

Methods and Patients: Between April 2001 and March, 2005, active, systematic, voluntary, national surveillance was performed through the Portuguese Paediatric Surveillance Unit. Case definition: any infant <90 days of age with GBS positive culture in any normally sterile site - blood, CSF, joint aspirate. Early-onset infection defined as in the first 6 full days after birth.

Results: 242 cases were reported (estimated cumulated incidence 0.54/1000live births [95%CI 0.47 - 0.61]). Infection occurred before day 7 in 194 babies (81%); 13% presented between day 7 and 28; 6% between day 28-90. The incidence of early-onset infection was 0.44/1000LB; 196 were term infants (81%), 160 of whom became ill before day 7; only 35 (22%) of these had one or more risk factors for infection. Overall, there were 229 positive blood cultures; 46 newborns had meningitis and 48 pneumonia. Mortality was 6.6% (16/242), was similar for early (6.7%) and late-onset infection (6.7%), but varied by gestation - 4.6% for term infants, 15.2% for preterm and 18% for babies born <1500g. Conclusions: GBS infection is predominantly an early infection of the term infant. Mortality is higher in preterm and VLBW infants. GBS prophylaxis based on risk factors would leave untreated 78% of term babies who will present with early-onset disease.