Gastrointestinal infectious disease complications following transplantation and their differentiation from immunosuppressant-induced gastrointestinal toxicities.

It is often very difficult to distinguish between infection-related and immunosuppression-related gastrointestinal (GI) complications after transplantation. The risk of infection itself is determined by the patient's net state of immunosuppression as well as the presence of anatomic or technical abnormalities and the patient's epidemiological exposures. Of the anatomic abnormalities, diverticulitis is a particular problem in transplant patients, with a high rate of perforation and abscess formation. The causes of infectious disease syndromes are very different immediately after, early after, and late after transplantation. Infection during the first month may result from a pre-existing infection in the donor or recipient, or from the surgical wound, endotracheal tube, vascular access or drainage. During 1-6 months after transplantation, viruses attack and, with sustained immunosuppression, make opportunistic infections possible. Beyond 6 months after transplantation, the 80% of patients with good result from the transplant are at risk primarily for community-acquired microbes, including such enteric pathogens as Salmonella. Of the remaining patients, 10% have chronic viral infections and the 10% who have poor allograft function are at greatest risk for opportunistic infection. This time line is helpful in determining whether a GI complication is likely to be related to infection rather than a specific effect of an immunosuppressant drug. Fever, inflammatory cells in the stool, abnormalities on endoscopy or computed tomography and leukocytosis can be useful in the diagnosis but are inconsistent markers for an infectious cause.