Fever can be a clinical manifestation present in pediatric infections, posing a challenge for the doctor who must decide whether or not to prescribe an antibiotic therapy. Routine blood tests can assist the doctor in making a decision, although their response times often do not allow for timely therapeutic decisions. Therefore, there is an increased risk of inappropriate prescribing antibiotics for children with viral infections, which contributes to the increase in antibiotic resistance. There is evidence suggesting the effectiveness of certain biomarkers in distinguishing viral from bacterial forms. Biomarkers of potential interest include tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), interferon gamma-inducible protein of 10 kDa (IP-10), and C-reactive protein. The combination of those tests could distinguish between bacterial and viral infections with 90-94% sensitivity, 88-92.8% specificity, 59-81% positive predictive value and 97-98.8% negative predictive value. This is prospective study using biological samples that aims to evaluate the best diagnostic algorithm for obtaining an early and accurate etiological diagnosis (bacterial infection vs viral infection) of a febrile pediatric patient presenting at the Emergency Department, by comparing the standard algorithm with the diagnostic algorithm integrated with the results of the multi-analytic test.

Inclusion criteria:

• Age ≥ 3 months and < 18 years
• Access to the Emergency Department during the study period
• Fever (body temperature ≥38°C) for less than 7 days
• Absence of an infectious focus or symptoms affecting the respiratory tract

Exclusion criteria:

• Fever for more than 7 days
• Antibiotic therapy for ≥ 48 hours
• Acute gastroenteritis
• HBV (hepatitis B virus) or HCV (hepatitis C virus) infection
• Active oncologic pathology
• Metabolic pathology
• Trauma or major surgery within the past 7 days