SERUM AND FAECAL INFLAMMATORY BIOMARKERS FOR DISTINGUISHING BACTERIAL AND VIRAL INFECTION IN YOUNG CHILDREN: A DIAGNOSTIC ACCURACY STUDY

Abstract: Background: It is hard to distinguish between bacterial and viral infections in young children with acute gastroenteritis (AGE). This uncertainty stimulates the frequent use of antibiotics empirically. An objective and rapid marker would be helpful for antimicrobial stewardship. The serum, haematological and faecal biomarkers were compared in this study. Methods: a case-control study in Baghdad, Iraq, enrolled 120 children. 50 individuals had bacterial AGE, 50 individuals had viral AGE and 20 individuals were apparently healthy controls. A complete blood count was performed and neutrophil to lymphocyte ratio (NLR) was calculated. We determined serum C-reactive protein (CRP) and procalcitonin (PCT). Three faecal markers (calprotectin, S100A12 and M2-Pyruvate kinase [M2-PK]) were also measured. The diagnostic performance was evaluated using receiver operating characteristic (ROC) analysis. Results: All markers showed higher results than in the viral disease. Procalcitonin was the best single discriminator (AUC 0.969). It was able to achieve 88.0% sensitivity and 96.0% specificity at a cut-off of 0.64 ng/mL. This was followed by c-reactive protein (AUC 0.941). The absolute neutrophil count performed almost as well (AUC 0.924). S100A12 was the best, with an AUC of 0.901, followed by calprotectin (AUC 0.873) as faecal markers. The NLR achieved good discrimination at no additional cost (AUC 0.879). M2-PK and the absolute lymphocyte count were the weakest markers. There was no association of biomarkers with child age or sex. Conclusions: Procalcitonin proved to be the best individual marker to distinguish bacterial from viral AGE. Simple neutrophil indices were as useful, at low cost. The addition of faecal neutrophils provided a direct measure of gut inflammation. A multi-tiered, combined panel can help minimize unnecessary antibiotic prescribing for paediatric gastroenteritis. Keywords: Acute gastroenteritis; procalcitonin; calprotectin; S100A12; neutrophil-to-lymphocyte ratio; M2-Pyruvate kinase; antimicrobial stewardship.