Increasing incidence of group B streptococcus neonatal infections in the Netherlands is associated with clonal expansion of CC17 and CC23

Dorota Jamrozy,Stephen D Bentley,Diederik van de Beek,Merijn W Bijlsma,Julian Parkhill,Arie van der Ende,Marcus C de Goffau,Taco W Kuijpers

doi:10.1038/s41598-020-66214-3

Abstract

Group B streptococcus (GBS) is the leading cause of neonatal invasive disease worldwide. In the Netherlands incidence of the disease increased despite implementation of preventive guidelines. We describe a genomic analysis of 1345 GBS isolates from neonatal (age 0–89 days) invasive infections in the Netherlands reported between 1987 and 2016. Most isolates clustered into one of five major lineages: CC17 (39%), CC19 (25%), CC23 (18%), CC10 (9%) and CC1 (7%). There was a significant rise in the number of infections due to isolates from CC17 and CC23. Phylogenetic clustering analysis revealed that this was caused by expansion of specific sub-lineages, designated CC17-A1, CC17-A2 and CC23-A1. Dating of phylogenetic trees estimated that these clones diverged in the 1960s/1970s, representing historical rather than recently emerged clones. For CC17-A1 the expansion correlated with acquisition of a new phage, carrying gene encoding a putative cell-surface protein. Representatives of CC17-A1, CC17-A2 and CC23-A1 clones were identified in datasets from other countries demonstrating their global distribution.

Highlights

Group B streptococcus (GBS), known as Streptococcus agalactiae, is a commensal bacterium that colonizes the human gastrointestinal and genital tracts[1]
Clustering of isolates using hierBAPS was highly concordant with multi-locus sequence typing (MLST) and clonal complexes (CC) assignment correlated with GBS population structure revealed by a core genome-based phylogeny (Supplementary Fig. S1)
A significant increase in isolates representing these clones, defined here as CC17-A1, CC17-A2 and CC23-A1, was sufficient to account for the overall increase in a number of GBS infection cases during this period

Summary

Introduction

Group B streptococcus (GBS), known as Streptococcus agalactiae, is a commensal bacterium that colonizes the human gastrointestinal and genital tracts[1]. Increased incidence of both EOD and LOD has been recently reported in some countries despite their implementation of national disease prevention guidelines, www.nature.com/scientificreports indicating that reassessment of their current prevention strategies is needed[4,11]. This includes the Netherlands, the UK and Ireland, where IAP is offered based on the presence of clinical risk factors, in contrast to a more widely implemented culture-based screening for GBS carriage during pregnancy[12]. In this study we examined the genomes of 1345 GBS isolates from neonatal invasive disease in the Netherlands collected between 1987 and 2016 to investigate changes in pathogen population during a previously reported rise in disease incidence[11]

Methods

Results

Conclusion