Group B Streptococcus neonatal invasive infections in Belgium, 2013-2016

Background
Since 2003, intrapartum antimicrobialprophylaxis (IAP) based on a universal screening for group B streptococcus (GBS) colonization at 35-37 weeks’ gestation is recommended in Belgium. Following, a decrease in the incidence of early-onset disease (EOD) was observed whereas late onset disease (LOD) have not changed. We describe the clinical and bacteriological characteristics of GBS neonatal invasive infections reported to the Belgian National Reference Centre (NRC) for GBS from 2013 to mid 2016.
Methods
On a voluntary base, all laboratories located in Belgium are invited to notify GBS neonatal invasive disease to the NRC, to send the isolate and fill a case-report questionnaire. This surveillance includes cases from 01.2013 to 07.2016. Following confirmation of identification, capsular-typing was performed by both agglutination and with PCR.
Results
Data from 157 GBS invasive neonatal cases were analysed: according to age at onset there were 70 EOD (median: day 0) and 57 LOD (median: 28 days). Among EOD cases, a male/female ratio was 0.75. The major types were III (35.7%), followed by Ia, II, V, Ib, IV, VI (20%, 14.3%, 12.9%, 10%, <10%). Fever and respiratory distress were frequently reported at onset. Meningitis was notified for 10,7% of cases. Among LOD cases, male/female ratio was 0.86. The predominant type was III (71.6%), followed mainly by Ia (13.4%). Gestational age at birth was significantly lower for LO cases and twins more frequent. The predominant characteristic at onset was fever and 32.5% developed meningitis. One death was reported in both groups of EOD and LOD. Antenatal GBS screening results and IAP were also analysed in regard to age at onset of diseases.
Conclusions
Clinical presentations were associated with age at onset of infection. Serotype III predominated in neonatal infections. Positive antenatal screening and appropriate IAP were not always protective for EOD and of course not for LOD.