Whole-genome sequencing in the investigation of recurrent invasive group A streptococcus outbreaks in a maternity unit

H. Dickinson, Mark Reacher, B. Nazareth, H. Eagle, D. Fowler, A. Underwood, Meera Chand-Kumar, Victoria Chalker, J. Coelho, R. Daniel, G. Kapatai, A. Al-Shabib, Richard Puleston*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Background: The clinical manifestations of group A streptococcus (GAS) (Streptococcus pyogenes) are diverse, ranging from asymptomatic colonization to devastating invasive disease. Maternity-related clusters of invasive GAS (iGAS) infection are complex to investigate and control, especially if recurrent. Aim: To investigate three episodes of emm 75 GAS/iGAS infection in maternity patients at one hospital site over a four-year period (two with monophyletic ancestry). Methods: The episodes are described, together with whole-genome sequence (WGS) isolate analyses. Single nucleotide polymorphism differences were compared with contemporaneous emm 75 genomes. Findings: Over the four-year study period, seven mothers had emm 75 GAS/iGAS and one mother had emm 3 iGAS (in year 4) (subsequently discounted as linked). Three (clinical/screening samples) of the seven babies of emm-75-positive mothers and three screened healthcare workers were positive for emm 75 GAS. WGS similarity suggested a shared ancestral lineage and a common source transmission, but directionality of transmission cannot be inferred. However, the findings indicate that persistence of a particular clone in a given setting may be long term. Conclusions: Occupational health procedures were enhanced, staff were screened, and antibiotic therapy was provided to GAS-positive staff and patients. The definitive source of infection could not be identified, although staff–patient transmission was the most likely route. The pattern of clonal GAS transmission over the four-year study period suggests that long-term persistence of GAS may have occurred.

Original languageEnglish
Pages (from-to)320-326
Number of pages7
JournalJournal of Hospital Infection
Volume101
Issue number3
DOIs
Publication statusPublished - Mar 2019

Bibliographical note

Funding Information:
This work was funded by Public Health England.

Keywords

  • Maternity
  • Streptococcus spp.
  • Whole-genome sequencing
  • iGAS

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