Pitfalls in the differential diagnosis of diarrhea after kidney transplantation: challenges in identifying Yersinia enterocolitica infection.

We present the case of a 14-year-old boy with a history of kidney transplantation due to focal segmental glomerulosclerosis who developed severe diarrhea and abdominal pain following an episode of antibody-mediated rejection. Despite stable kidney function, the patient required increased immunosuppressive therapy, raising concerns regarding possible drug-induced enteritis or infections. Initial investigations, including stool tests for common pathogens and imaging, failed to identify the causative agent. Colonoscopy revealed thickening of the terminal ileum and aphthae in the colon; however, common infections, such as cytomegalovirus and Epstein-Barr virus, were excluded. Given the persistence of symptoms and worsening ultrasound findings showing enlarged lymph nodes and mucosal thickening, Yersinia enterocolitica infection was suspected. Special stool culture media for Yersinia spp. confirmed the infection, and the patient responded well to antibiotic therapy. Our case highlights several challenges in diagnosing gastrointestinal infections in kidney transplant recipients, including the non-specific nature of symptoms and the difficulty in distinguishing between drug-induced enteritis, viral or bacterial infections, and other transplant-related complications. This underscores the importance of considering rare pathogens, such as Yersinia, in the differential diagnosis of gastrointestinal symptoms in immunocompromised transplant patients, including pediatric patients, and emphasizes the need for specialized diagnostic techniques, such as stool culture on selective media, to confirm the diagnosis.