P-1290. Invasive group A streptococcal infection in children in Toronto, Canada
Bibliographic record
Abstract
Abstract Background Rising cases of invasive group A streptococcus (iGAS) in children have been reported globally. We assessed the epidemiology of pediatric iGAS over three decades. The annual incidence of invasive GAS infections in children in Toronto and Peel Region during the years 1992-2023 Methods Since 1992, the Toronto Invasive Bacterial Diseases Network has conducted surveillance for iGAS in Toronto/Peel Region, Canada. The National Microbiology Laboratory provides emm typing, and Statistics Canada supplies population data. iGAS data were analyzed by age group—toddlers (0-4 yrs), young children (5-9 yrs), and older children (10-17 yrs)— and over time from 1992 to 2024. emm types in pediatric cases per 100,000 population in Toronto and Peel Region from 1992 to 2023. Results 506 pediatric iGAS cases were identified. Figure 1 shows the incidence by age group. 61% of cases were male; 33% had underlying conditions. Main presentations were soft tissue infection (30%), bacteremia with no focus (22%), bone/joint infections (20%) and pneumonia (16%). Streptococcal toxic shock syndrome (STSS) occurred in 5.7% of cases, and necrotizing fasciitis (NF) in 2.6%. Positive blood cultures were found in 71% of cases, with additional sterile site cultures in 20%. emm1 (42%) and emm12 (16%) were the most common types (Figure 2), with M1UK comprising 63% of emm1 isolates in 2022/2023. During the period of pandemic restrictions (Mar 2020-Apr 2022), iGAS cases declined, and emm1 disappeared. As restrictions eased, emm1 and, to a lesser extent, emm12 rebounded (Figure 3). Seasonality, with increased winter/spring cases, became more pronounced (Figure 4). Toddlers had higher rates of bacteremia without focus (27% vs. 14%, p=0.01) and emm12 (20% vs. 8.4%, p=0.02) than older children. Younger children had higher rates of bone/joint infections than toddlers (28% vs. 16%, p=0.004). Rates of STSS, NF, and 30-day mortality were consistent across age groups and time, with no association to specific emm types, except for higher mortality in emm4 [12.5% vs. 3.6%, OR 3.8 (1.2-12.1)]. Increasing pneumonia rates over time were associated with emm1. In multivariate analysis, pneumonia [OR 7.2 (2.9-17.6)], NF [OR 15.5 (4.2-58)], and increased age [OR 1.8 (1.03-3.2)] predicted STSS. Monthly pediatric iGAS cases in relation to pandemic public health restrictions in Toronto and Peel Region from April 2018 to March 2024. Conclusion The recent rise in pediatric iGAS infections is a public health concern. Incidence has increased, but severity remains unchanged. emm1 transmission seems more susceptible to control by public health measures. Continuous surveillance is essential. Seasonality of iGAS in children in Toronto/Peel region, 1992-2023 Disclosures Allison McGeer, MD, AstraZeneca: Honoraria|GSK: Honoraria|Merck: Honoraria|Moderna: Honoraria|Novavax: Honoraria|Pfizer: Grant/Research Support|Pfizer: Honoraria|Roche: Honoraria|Seqirus: Grant/Research Support|Seqirus: Honoraria
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.003 |
| 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) | 0.007 | 0.001 |
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".