A patient presents three months post-transplant with fever. What are the common and uncommon infections that should be in the differential diagnosis?
In an immunocompromised patient with fever, the presence of infection must be ruled out. The types of infection that are seen depend on: the time post-transplant; the type of immunosuppression; the use or non-use of prophylactic medications; and the serologic status of the donor and recipient. For example, donor-derived bacterial infections more commonly occur in the very early post-transplant period. Others, like BK virus infection, usually do not occur in the first few weeks post-transplant, but often present in the one or two years post-transplant. Disease caused by other pathogens, such as hepatitis C, may take several years to become apparent.
In a patient three months post-transplant, routine urinary tract infections and pneumonia need to be ruled out. Viral infections such as cytomegalovirus may be seen if no prophylaxis was used or has been recently discontinued, especially if the patient is a CMV mismatch. Pneumocystis jiroveci or toxoplasmosis may also be seen in the absence of prophylaxis. If testing for the above is negative, then less common bacterial, viral and fungal causes need to be considered.