Clinical and Epidemiologic Features of Group A Streptococcal Pneumonia in Ontario, Canada | Infectious Diseases | JAMA Internal Medicine | JAMA Network
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Original Investigation
February 24, 2003

Clinical and Epidemiologic Features of Group A Streptococcal Pneumonia in Ontario, Canada

Author Affiliations

From the Department of Infectious Diseases, University of Toronto, Toronto, Ontario (Dr Muller); Departments of Microbiology, Toronto Medical Laboratories and Mount Sinai Hospital, Toronto (Drs Low and McGeer and Ms Green); Department of Microbiology, Sunnybrook and Women's College Health Sciences Centre, Toronto (Dr Simor); Department of Medicine, Hamilton Health Sciences Corporation, Hamilton, Ontario (Dr Loeb); and Calgary Laboratory Services, Calgary, Alberta (Dr Gregson).

Arch Intern Med. 2003;163(4):467-472. doi:10.1001/archinte.163.4.467

Background  Since the 1960s, group A streptococcus (GAS) has accounted for less than 1% of cases of community-acquired pneumonia. During the past 2 decades there has been a resurgence of invasive GAS infection, but no large study of GAS pneumonia has been performed.

Methods  To determine the clinical and epidemiologic features of GAS pneumonia, we conducted prospective, population-based surveillance of all invasive GAS infection in residents of Ontario from January 1, 1992, through December 31, 1999.

Results  Of 2079 cases of invasive GAS infection, 222 (11%) represented GAS pneumonia. The incidence of GAS pneumonia ranged from 0.16 per 100 000 in 1992 to 0.35 per 100 000 in 1999. Most cases were community acquired (81%). Forty-four percent of nursing home–acquired cases occurred during outbreaks. The case fatality rate was 38% for GAS pneumonia, compared with 12% for the entire cohort with invasive GAS infection and 26% for patients with necrotizing fasciitis. The presence of streptococcal toxic shock syndrome (odds ratio, 19; 95% confidence interval, 8.4-42; P = .001) and increasing age (odds ratio per decade, 1.45; 95% confidence interval, 1.2-1.7; P<.001) were associated with fatal outcome. Time to death was rapid, with a median of 2 days despite antimicrobial therapy and supportive measures.

Conclusions  Group A streptococcal pneumonia is a common form of invasive GAS disease but remains an uncommon cause of community-acquired pneumonia. Progression is rapid despite appropriate therapy. The incidence is similar to, and the case fatality rate higher than, that of necrotizing fasciitis.