Uncovering infant group B streptococcal (GBS) disease clusters in the UK and Ireland through genomic analysis: a population-based epidemiological study

Collin, S. M. et al. (2020) Uncovering infant group B streptococcal (GBS) disease clusters in the UK and Ireland through genomic analysis: a population-based epidemiological study. Clinical Infectious Diseases, (doi: 10.1093/cid/ciaa1087) (Early Online Publication)

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Background: The true frequency of hospital outbreaks of invasive group B streptococcal (iGBS; Streptococcus agalactiae) disease in infants is unknown. We used whole genome sequencing (WGS) of iGBS isolates collected during a period of enhanced surveillance of infant iGBS disease in the UK and Ireland to determine the number of clustered cases. Methods: Potentially linked iGBS cases from infants with early (<7 days of life) or late-onset (7–89 days) disease were identified from WGS data (HiSeq 2500 platform, Illumina) from clinical sterile site isolates collected between 04/2014 and 04/2015. We assessed time and place of cases to determine a single-nucleotide polymorphism (SNP) difference threshold for clustered cases. Case details were augmented through linkage to national hospital admission data and hospital record review by local microbiologists. Results: Analysis of sequences indicated a cutoff of ≤5 SNP differences to define iGBS clusters. Among 410 infant iGBS isolates, we identified 7 clusters (4 genetically identical pairs with 0 SNP differences, 1 pair with 3 SNP differences, 1 cluster of 4 cases with ≤1 SNP differences) of which 4 clusters were uncovered for the first time. The clusters comprised 16 cases, of which 15 were late-onset (of 192 late-onset cases with sequenced isolates) and 1 an early-onset index case. Serial intervals between cases ranged from 0 to 59 (median 12) days. Conclusions: Approximately 1 in 12 late-onset infant iGBS cases were part of a hospital cluster. Over half of the clusters were previously undetected, emphasizing the importance of routine submission of iGBS isolates to reference laboratories for cluster identification and genomic confirmation.

Item Type:Articles
Status:Early Online Publication
Glasgow Author(s) Enlighten ID:Reynolds, Dr Arlene and Smith, Professor Andrew
Authors: Collin, S. M., Groves, N., O'Sullivan, C., Jauneikaite, E., Patel, D., Cunney, R., Meehan, M., Reynolds, A., Smith, A., Lindsay, D., Doherty, L., Davies, E., Chalker, V., Lamb, P., Afshar, B., Balasegaram, S., Coelho, J., Ready, D., Brown, C. S., Efstratiou, A., Le Doare, K., Sriskandan, S., Heath, P. T., and Lamagni, T.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing > Dental School
Journal Name:Clinical Infectious Diseases
Publisher:Oxford University Press
ISSN (Online):1537-6591
Published Online:07 August 2020

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