H Dickinson1, M Reacher1, B Nazareth2, H Eagle3, D Fowler3, A Underwood4, M Chand5, V Chalker4, J Coelho4, R Daniel4, G Kapatai1, A Al-Shabib4, R Puleston6. 1. Eastern Field Epidemiology Unit, National Infection Service, Cambridge, UK. 2. Anglia Health Protection Team, Thetford, UK. 3. North West Anglia NHS Foundation Trust, Executive and Infection Control Teams, Peterborough, UK. 4. PHE Microbiology Reference Services, National Infection Service, London, UK. 5. PHE Microbiology Reference Services, National Infection Service, London, UK; Guy's & St Thomas Hospitals NHS Foundation Trust, London, UK; NIHR Health Protection Research Unit in Respiratory Infections at Imperial College London, London, UK. 6. Eastern Field Epidemiology Unit, National Infection Service, Cambridge, UK; University of Nottingham, School of Medicine, Division of Epidemiology and Public Health, Nottingham, UK. Electronic address: richard.puleston@phe.gov.uk.
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.
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.
Authors: Barbara Strauss; Martin Tepper; Diane Lu; François Gagnon; Eric Girard; Walter Demczuk; Irene Martin; Martine Massé; Kirsten Barnes Journal: Can Commun Dis Rep Date: 2020-09-03