Microarray Analysis of Group B Streptococci Causing Invasive Neonatal Early- and Late-onset Infection

Group B Streptococcus is the leading cause of meningitis and sepsis in newborns. Until now, there is no data of fast and simple typing of group B Streptococcus virulence factors using a genetic microarray and comparing these data to clinical manifestations.

A prospective active surveillance study was conducted via 2 independent and nationwide reporting systems, the German Pediatric Surveillance Unit (ESPED) and the Laboratory Sentinel Group at Robert Koch-Institute. Surveillance was performed between 2001 and 2003 and between 2008 and 2010. Typing of virulence factors, serotypes, pilus islands and alpha-like proteins was done by means of a newly developed microarray method.

We evaluated 475 isolates of invasive neonatal infections. Predominant virulence factors were serotype III (63%), pilus island 2b and pilus island 1 (50%) and alp rib (64%) (alp - alpha-like protein, rib -resistance to proteases, immunity, group B). There was no significant change over time or geographically within Germany. Serotype III, pilus island 2b + 1 and alp rib showed significant associations with late-onset disease and meningitis, whereas alp 5 had a significant association with early-onset disease. Based on serotypes, pilus islands and alpha-like proteins, it was possible to cluster 86% of all isolates into 5 genetic groups.

The molecular epidemiology of a large collection of invasive neonatal infections showed similar distributions, as shown in smaller cohorts before. The microarray used proved to be a fast and reliable technique. Using this new tool, we were able to cluster the isolates according to their virulence factors. The clusters showed a better association with clinical data than single virulence factors.