Objective: To develop and prospectively validate a clinical algorithm (Pedi-AII-Alg) for the early diagnosis and risk stratification of children with acute intestinal infections (AII), aimed at guiding diagnostic testing and clinical management. Methods: A prospective, two-phase diagnostic accuracy study was conducted at a tertiary pediatric emergency department. Phase 1 (Development): Key clinical predictors (e.g., patient age, fever >39°C, bloody diarrhea, vomiting frequency, symptom duration) and dehydration status (assessed by the Clinical Dehydration Scale - CDS) were identified through literature review and expert consensus. These were used to build a tiered algorithm. Phase 2 (Validation): The algorithm was prospectively applied to 420 children (aged 6 months to 5 years) presenting with AII. The algorithm stratified patients into three pathways: Low-Risk (likely viral, supportive care), Moderate-Risk (requiring rapid RDT/toxin testing), and High-Risk (requiring comprehensive diagnostics, including multiplex PCR, and/pre-emptive admission). The algorithm’s performance was compared against a reference standard diagnosis, defined by multiplex PCR results (e.g., BioFire GI Panel) and clinical outcomes at 48-hour follow-up. Results: The Pedi-AII-Alg algorithm classified 55% (n=231) of patients as Low-Risk, 30% (n=126) as Moderate-Risk, and 15% (n=63) as High-Risk. In the Low-Risk group, the algorithm demonstrated a 96.5% negative predictive value (NPV) for bacterial infection, suggesting it safely rules out the need for antibiotics. In the High-Risk group, sensitivity for detecting severe bacterial infection (e.g., Shigella, Salmonella, E. coli O157) or severe dehydration (CDS > 8) was 98.1%. Application of the algorithm was projected to reduce unnecessary antibiotic prescriptions by 45% and optimize diagnostic testing by 50% compared to unguided clinical practice. Conclusion: The Pedi-AII-Alg is an effective, validated clinical decision-support tool. It accurately stratifies pediatric AII patients by risk, allowing for rational allocation of diagnostic resources, promoting antimicrobial stewardship, and safely identifying children who can be managed with supportive care, versus those requiring admission and targeted therapy.

Acute intestinal infections (AII), pediatrics, clinical algorithm, clinical decision support, early diagnosis, risk stratification, dehydration, Clinical Dehydration Scale (CDS), antimicrobial stewardship.

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