Isolation and molecular detection of Salmonella enterica among children suffering from acute diarrhea

Background: Salmonella enterica remains a leading etiological agent of pediatric gastroenteritis in the developing world. It is a major public health issue due to its link with severe dehydration and other morbidities. The aim of the current study was to molecularly diagnose Salmonella enterica and study the virulence genes of the bacteria and the host response genes to the severity of illness in children with acute diarrhea. Methods: Stool samples were obtained from 100 children aged 1 to 10 years presenting with acute diarrhea. Total RNA was obtained using a microbiome-specific method, succeeded by cDNA synthesis and quantitative RT-PCR to evaluate bacterial virulence genes (invA, fliC, sipA, spvC) and two genes found in the children's bodies. The IL8 (CXCL8) gene acts as a biomarker for inflammation. The other gene was MUC2, which makes mucus protect the gut lining. Results: Bacterial genes demonstrated significant expression in 12% of children, mostly in those under five years of age. The sipA gene showed the highest expression (mean 3.2 ± 0.3), followed by spvC (mean 2.9 ± 0.6), invA (mean 2.8 ± 0.4), and fliC (2.4 ± 0.5). Increased IL8 expression was markedly connected to the presence of sipA and spvC. This means their bodies were having a strong inflammatory reaction. However, MUC2 expression was reduced, particularly in children with severe symptoms, suggesting compromised mucosal barrier function. Age and severity stratification confirmed that younger children exhibited higher sipA and IL8 levels but lower MUC2 expression. Children with severe symptoms were characterized by significantly elevated sipA and IL8 levels and further reductions in MUC2. Conclusion: These findings highlight a molecular link between S. enterica virulence and host inflammatory and mucosal responses. The results suggest that sipA and IL8 may serve as biomarkers for disease severity, while reduced MUC2 suggests potential biomarkers for severe pediatric diarrhea.