High Incidence of Invasive Group A Streptococcus Disease Caused by Strains of Uncommon emm Types in Thunder Bay, Ontario, Canada.
An outbreak of type emm59 invasive group A Streptococcus (iGAS) disease was declared in 2008 in Thunder Bay District, Northwestern Ontario, 2 years after a countrywide emm59 epidemic was recognized in Canada. Despite a declining number of emm59 infections since 2010, numerous cases of iGAS disease continue to be reported in the area. We collected clinical information on all iGAS cases recorded in Thunder Bay District from 2008 to 2013. We also emm typed and sequenced the genomes of all available strains isolated from 2011 to 2013 from iGAS infections and from severe cases of soft tissue infections. We used whole-genome sequencing data to investigate the population structure of GAS strains of the most frequently isolated emm types. We report an increased incidence of iGAS in Thunder Bay compared to the metropolitan area of Toronto/Peel and the province of Ontario. Illicit drug use, alcohol abuse, homelessness, and hepatitis C infection were underlying diseases or conditions that might have predisposed patients to iGAS disease. Most cases were caused by clonal strains of skin or generalist emm types (i.e., emm82, emm87, emm101, emm4, emm83, and emm114) uncommonly seen in other areas of the province. We observed rapid waxing and waning of emm types causing disease and their replacement by other emm types associated with the same tissue tropisms. Thus, iGAS disease in Thunder Bay District predominantly affects a select population of disadvantaged persons and is caused by clonally related strains of a few skin and generalist emm types less commonly associated with iGAS in other areas of Ontario.
Public Health Ontario, Toronto, Ontario, Canada.
Taryn B T
TB
Athey
Public Health Ontario, Toronto, Ontario, Canada.
Sarah
S
Teatero
Thunder Bay District Health Unit, Thunder Bay, Ontario, Canada Department of Health Sciences, Lakehead University, Thunder Bay, Ontario, Canada.
Lee E
LE
Sieswerda
Public Health Ontario, Toronto, Ontario, Canada Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada.
Jonathan B
JB
Gubbay
Public Health Ontario, Toronto, Ontario, Canada Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
Alex
A
Marchand-Austin
Public Health Ontario, Toronto, Ontario, Canada.
Aimin
A
Li
McGill University and Genome Quebec Innovation Centre, Montreal, Quebec, Canada.
Jessica
J
Wasserscheid
McGill University and Genome Quebec Innovation Centre, Montreal, Quebec, Canada.
Ken
K
Dewar
Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada Department of Microbiology, Mount Sinai Hospital, Toronto, Ontario, Canada.
Allison
A
McGeer
Thunder Bay District Health Unit, Thunder Bay, Ontario, Canada.
David
D
Williams
Public Health Ontario, Toronto, Ontario, Canada Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada nahuel.fittipaldi@oahpp.ca.
Nahuel
N
Fittipaldi
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000942:Antigens, Bacterial / Q000235:genetics*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D060005:Genotyping Techniques; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D012307:Risk Factors; D017422:Sequence Analysis, DNA; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D013297:Streptococcus pyogenes / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D055815:Young Adult
D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D002352:Carrier Proteins; C014689:streptococcal M protein