314. Invasive Group A Streptococcal Infections in Ontario, Canada: 1992-2013
Session: Poster Abstract Session: HAI: Epidemiology
Thursday, October 8, 2015
Room: Poster Hall

Invasive Group A streptococcal (iGAS) infections continue to cause significant morbidity and mortality. We explored trends in incidence, M-type, disease presentation, outcome, and antimicrobial resistance of iGAS infections in Ontario, Canada over a 22-year period.


TIBDN has performed a prospective, population-based surveillance for all iGAS infections in metropolitan Toronto and Peel regions in Ontario, Canada since January 1, 1992. Clinical information was collected from health care providers. M typing was performed from January 1992 to September 2006 and emm typing from October 2006 to December 2013.


Overall, 2282 episodes of iGAS were identified; 1074 in the “former” cohort (1992-2002) and 1212 in the “recent” cohort (2003-2013). The average incidence per 100,000 residents was 2.7 in the former cohort and 2.8 in the recent cohort (p=0.69). For each cohort, the most common clinical presentation was skin and soft-tissue infections, 47.8% and 43.3%. The percentage of cases of streptococcal toxic shock syndrome increased from 15.6% of patients in the former cohort to 19.3% in recent cohort (p=0.08), while cases of necrotizing fasciitis decreased from 8.4% to 6.1% (p=0.02). Case fatality rates declined over time, from 16.8% in 1992-5 to 13.6% in 2010-13 (p=0.06). Both nosocomial and nursing home-associated infections declined significantly from 12.9% to 8.3% (p=0.01) and 7.4% to 4.2% (p=0.009), respectively.

M serotype distribution varied substantially from year to year (M3 from 0 to 19.7%, M1 from 7.4-37%) but remained stable over each cohort, with the exception of the emergence of M89 in the recent cohort. M1 was consistently the most common and exhibited a four to five year cyclical pattern. Erythromycin resistance increased from 2.2% in 1992-5 to 19.5% in 2008-10, then declined to 7.5% in 2013. 


The overall incidence of iGAS remains unchanged over 22 years. The proportion of hospital and nursing home-associated cases has decreased, as have case fatality rates. M1 infections have a 4-5 year periodicity, M89 has emerged, and erythromycin resistance has varied significantly over time. An effective vaccine will be required to substantially reduce iGAS morbidity and mortality.

Christopher Kandel, MD1, Nick Daneman, MD, MSc2, Walt Demczuk, BSc3, Wayne Gold, MD, FRCPC4, Karen Green, MSc5, Amanda Hong, BSc5, Irene Martin, BSc6, Agron Plevneshi, BSc5, Wallis Rudnick, MSc5, Ray Saginur, MD7, Benjamin Schwartz, MD8, Abdu Sharkawy, MD, FRCPC9, Andrew E. Simor, MD, FRCPC, FACP, FIDSA, FSHEA10, Gregory Tyrrell, PhD11, Louis Valiquette, MD, MSc12 and Allison Mcgeer, MD, MSc, FSHEA13, (1)Department of Medicine, University of Toronto, Toronto, ON, Canada, (2)Division of Infectious Diseases & Clinical Epidemiology, University of Toronto, Toronto, ON, Canada, (3)Public Health Agency of Canada, Ottawa, ON, Canada, (4)Medicine, University of Toronto, Toronto, ON, Canada, (5)Mount Sinai Hospital, Toronto, ON, Canada, (6)National Microbiology Laboratory, Winnipeg, MB, Canada, (7)Ottawa Health Research Institute, Ottawa, ON, Canada, (8)CARE, Atlanta, GA, (9)Medicine, University Health Network, University of Toronto, Toronto, ON, Canada, (10)Microbiology, Sunnybrook Health Sciences Centre, Toronto, ON, Canada, (11)Walter Mackenzie Health Sciences Centre, University of Alberta, Edmonton, AB, Canada, (12)Microbiology and Infectious Diseases, Université de Sherbrooke, Sherbrooke, QC, Canada, (13)Public Health Sciences & Pathobiology, University of Toronto, Toronto, ON, Canada


C. Kandel, None

N. Daneman, None

W. Demczuk, None

W. Gold, None

K. Green, None

A. Hong, None

I. Martin, None

A. Plevneshi, None

W. Rudnick, None

R. Saginur, None

B. Schwartz, None

A. Sharkawy, None

A. E. Simor, None

G. Tyrrell, None

L. Valiquette, None

A. Mcgeer, None

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