This investigator-initiated randomized controlled trial compares the clinical impact of real time PCR of fecal samples in children with acute gastrointestinal symptoms at a pediatric emergency room. Specifically, the trial compares immediate testing of fecal samples using a multiplex PCR panel to a a control group with delayed test results.

Acute gastroenteritis is one of the most common reasons for pediatric emergency visits in both general and pediatric emergency departments. For most of the children rehydration is the only therapy needed. However, a range of bacterial pathogens and parasites may need accurate diagnosis and targeted antimicrobial therapy. Use of molecular multiplex testing has increased detection of pathogens in children with acute gastrointestinal symptoms. The PCR tests currently available enable rapid identification of gastrointestinal pathogens, with the test results often being available during the day sample was taken. However, it is unclear which of the patients are most likely to benefit from testing. Also, there is considerable uncertainty about the cost-effectiveness of the multiplex panels used to test for suspected infectious gastroenteritis in hospital and community settings. The previous study by the research group demonstrated that acute gastrointestinal symptoms are one of the most common diagnoses and a major cost in high-income population.

The main hypothesis of the study is that real time multiplex PCR testing for gastrointestinal pathogens at pediatric emergency department setting could provide clinical benefit by allowing 1) earlier initiation of appropriate antimicrobial treatment, 2) reduce use of unnecessary antimicrobial treatment and 3) improve identification of conditions in need for follow-up.

To estimate the usefulness of real time multiplex PCR testing, an investigator-driven academic randomized (1:1) controlled trial will be conducted at the Pediatric Emergency Department of Oulu University Hospital, Finland. For eligibility, children aged under 16 years arriving to pediatric emergency due to acute gastrointestinal symptoms will be assessed. After obtaining the written consent, fecal specimens will be collected by the nurses from the first stool after arriving to hospital.

Multiplex PCR detects 13 gastrointestinal bacterial pathogens, 5 viral pathogens ands 4 parasitic species. QIAStat-Dx gastrointestinal panel 2 will be used.

The trial will compare two groups:

1. Intervention group will be tested by a relay-time PCR panel as soon as the fecal sample will arrive in the laboratory and the results will be given to the clinical physicians
2. Control group will undergo similar sampling as the intervention group but the results will be made available after 72 hours of sampling.

The composite primary outcome consists of three outcomes which are evaluated using medical records: 1) correctly targeted antimicrobial treatment, 2) untargeted antimicrobial treatment and 3) identification of conditions that require specific follow-up such as shiga-toxin producing EHEC.

Secondary outcomes, evaluated by medical records and electronic survey sent to families two weeks after the study visit, include: proportion of correctly targeted antimicrobial treatment, proportion of untargeted antimicrobial treatment, proportion of conditions in need for hospitalization or specific follow-up, time needed for clinician to receive the results of the samples, length of hospital stay, time to correct diagnosis, resolution of symptoms, laboratory and radiology costs, total costs, need for surgical consultation and proportion of patients needing surgical procedure, proportion of unscheduled revisits and proportion of correctly used hospital infection control measures.

Inclusion Criteria:

• Child or adolescent < 16 years of age
• Visiting pediatric ED
• Presence of gastrointestinal symptom or symptoms (diarrhea, vomiting or abdominal pain)

Exclusion Criteria:

• Need of cardiopulmonary resuscitation at the ED
• Need of immediate transfer to the intensive care unit
• Hemato-oncological disease
• Severe immunosuppression
• Bloody diarrhea
• Clinical suspicion of typhoid/paratyphoid fever

The individual participant data on the primary outcome of participants according to groups. No identifying participant data will be shared according to EU GDPR regulations. Study protocol and statistical analysis plan will be hared upon submission of the manuscript.

Upon the submission of the manuscript