Invasive Group A Streptococcal Infections, Clinical Manifestations and Their Predictors, Montreal, 1995–2002

摘要

We identified 306 invasive group A streptococcal infec-tions (IGASI) by passive population-based surveillance inMontreal, Canada, from 1995 to 2001. The average yearlyreported incidence was 2.4 per 100,000 persons, with a14 death rate. Among clinical manifestations, incidenceof pneumonia increased from 0.06 per 100,000 in 1995 to0.50 per 100,000 in 2000. Over a span of 7 years, the oddsof developing pneumonia increased (odds ratio OR =1.21, 95 confidence interval CI 1.0–1.5), while theydecreased for soft-tissue infections (OR = 0.86, 95 CI0.7–1.0). Serotypes M1 and M3 accounted for 30 ofIGASI. However, neither serotype was significantly associ-ated with specific clinical manifestations, which suggeststhat manifestation development among IGASI might beattributable to host or environmental factors rather than thepathogen. In our study, these factors included age, gender,underlying medical conditions, and living environment, yetnone explained temporal changes in risk for pneumoniaand soft-tissue infections