Invasive Group A Streptococcal Infections in Ontario, Canada: 1992–2013
Bibliographic record
Abstract
Background. 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. Methods. TIBDN has performed a prospective, population-based surveillance for all iGAS infections in metropolitan Toronto and Peel regions in Ontario, Canada since 1 January 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. Results. 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 1992-1995 to 19.5% in 2008-2010, then declined to 7.5% in 2013. Conclusion. 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. Disclosures. All authors: No reported disclosures.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.006 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".