Salmonella Typhimurium infection complicating very early-onset inflammatory bowel disease presenting with Pseudo-intussusception: a case report.

The clinical manifestations of acute non-typhoidal Salmonella infection can overlap with underlying very early-onset inflammatory bowel disease (VEO-IBD), complicating early differential diagnosis. We report a 5-year-old boy who presented with fever, paroxysmal abdominal pain, and high-volume watery hematochezia. Initial abdominal ultrasonography revealed a "concentric ring sign" mimicking intussusception, while laboratory tests concurrently demonstrated elevated serum total immunoglobulin E (IgE) levels. Subsequent water-soluble gastrointestinal contrast studies and computed tomography ruled out mechanical intestinal obstruction. Early endoscopy and mucosal biopsy revealed cryptitis and chronic active inflammation from the rectum to the sigmoid colon, and stool cultures isolated Salmonella Typhimurium, with serum total IgE peaking at 2965 IU/mL. Based on these clinical findings, the patient was diagnosed with concurrent acute Salmonella Typhimurium infection and VEO-IBD. The patient received a combined regimen of systemic intravenous cefotaxime sodium and localized therapy comprising dexamethasone retention enemas and mesalazine suppositories, with symptom resolution within 10 days. This case illustrates the value of multimodal imaging and early endoscopy in differentiating overlapping enteric infections from VEO-IBD, and suggests that integrating systemic antimicrobials with localized anti-inflammatory agents may be a feasible therapeutic strategy.