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Background Understanding the burden of influenza is necessary to optimize recommendations for influenza vaccination. We describe the epidemiology of severe influenza in 50- to 64-year-old residents of metropolitan Toronto and Peel region, Canada, over 7 influenza seasons. Methods Prospective population-based surveillance for hospitalization associated with laboratory-confirmed influenza was conducted from September 2010 to August 2017. Conditions increasing risk of influenza complications were as defined by Canada's National Advisory Committee on Immunization. Age-specific prevalence of medical conditions was estimated using Ontario health administrative data. Population rates were estimated using Statistics Canada data. Results Over 7 seasons, 1228 hospitalizations occurred in patients aged 50–64 years: 40% due to A(H3N2), 30% A(H1N1), and 22% influenza B. The average annual hospitalization rate was 15.6, 20.9, and 33.2 per 100 000 in patients aged 50–54, 55–59, and 60–64 years, respectively; average annual mortality was 0.9/100 000. Overall, 33% of patients had received current season influenza vaccine; 963 (86%) had ≥1 underlying condition increasing influenza complication risk. The most common underlying medical conditions were chronic lung disease (38%) and diabetes mellitus (31%); 25% of patients were immunocompromised. The average annual hospitalization rate was 6.1/100 000 in those without and 41/100 000 in those with any underlying condition, and highest in those with renal disease or immunocompromise (138 and 281 per 100 000, respectively). The case fatality rate in hospitalized patients was 4.4%; median length of stay was 4 days (interquartile range, 2–8 days). Conclusions The burden of severe influenza in 50- to 64-year-olds remains significant despite our universal publicly funded vaccination program. These data may assist in improving estimates of the cost-effectiveness of new strategies to reduce this burden. [ABSTRACT FROM AUTHOR]

In multivariable analysis of associations between initial antibiotic therapy and clinical outcomes in 5005 patients with microbiologically confirmed Streptococcus pneumoniae infections,"discordant" empiric antibiotic therapy was not associated with 30-day mortality rate (hazard ratio, 0.94; 95% confidence interval, .67-1.32). [ABSTRACT FROM AUTHOR]

Background. Background Invasive Group A streptococcal (iGAS) infections remain a substantial source of morbidity and mortality. We explore the clinical and molecular epidemiology of iGAS infections in Toronto, Ontario, Canada over a 26-year period. Methods The Toronto Invasive Bacterial Diseases Network has performed population-based surveillance for iGAS infections in metropolitan Toronto and Peel regions since 1992. Participating microbiology laboratories report and submit sterile site specimens for central processing. M typing was performed on iGAS isolates until September 2006; thereafter emm typing was performed. Clinical information was collected by chart review using standardized collection forms. Results Over the 26-year period there were 2819 iGAS infections, representing an average incidence of 2.85 per 100,000 residents with a nadir of 1.65 in 1993 and a peak of 4.52 in 2014. Nosocomial infections occurred in 8.9% (251/2,819). There was substantial variation in annual incidence rates over the study period with increases from 1992 until 2002 and then 2004 until 2014 (analysis for trend, P < 0.001). Skin and soft-tissue infections were the most common clinical presentation, accounting for 33.2% (936/2,819), followed by bacteremia without a focus in 15.4% (435/2,819). Necrotizing fasciitis was observed in 7.4% (208/2,819) and criteria for toxic shock syndrome were met in 17.6% (497/2,819). Overall case fatality within 30 days of hospitalization was 15.3% (95% confidence interval 14.0 to 16.6) and did not change over time. M serotype distribution varied yearly with the most common type being M1 at 22.2% (626/2,189) followed by M12 at 8.2% (230/2,189), then M89 at 5.8% (163/2,189). Antibiotic susceptibility was available from 1998 onwards with overall clindamycin susceptibility at 92.3% (1,957/2,121) and erythromycin susceptibility at 87.9% (1864/2,121). Conclusion The incidence of iGAS in Toronto, Ontario has varied over time, with no recent increase apparent. Similar to worldwide observations, M1 serotype was the most commonly isolated; most common serotypes demonstrated cyclical variation. Case fatality rates have remained relatively constant making the development of a vaccine imperative. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]