Infection as a complication of heart transplantation

Infection and cardiac rejection are the most significant causes of morbidity and mortality after heart transplantation. At some transplant centers, more than half of the early transplantation-related deaths are the result of infection. The infectious agents may be transmitted to the host by means of the allograft, through blood transfusion, by nosocomial or environmental routes, or they may represent endogenous microbial flora or reactivation of a prior infection. The frequency of infectious complications is generally related to the degree of immunosuppressive therapy required to prevent graft rejection. Both the composition of the immunosuppressive regimen and the dosage of the immunosuppressive drugs affect the infection rate. Recent protocols, employing a combination of cyclosporine, steroids, and azathioprine cause less toxicity and lower infection rates than protocols that rely solely on cyclosporine and steroids or protocols utilized in the 1970s, which did not contain cyclosporine. A literature review of data reported from 12 transplant centers, encompassing 384 patients who received their transplantation in the era of cyclosporine, revealed infections in 221 patients (57.6%), with 20 infection-related deaths (5.2%). All classes of microorganisms infected the heart transplant recipients. The most frequent agents included staphylococci, gram-negative enteric, Nocardia (bacterial); Aspergillus, Candida, Cryptococcus (fungal); cytomegalovirus, herpes simplex, herpes zoster (viral); and Pneumocystis carinii, Toxoplasma gondii (protozoal). The respiratory tract, urinary tract, and skin were the most common sites of infection. Most infection-related fatalities were caused by bacterial sepsis, Aspergillus, or cytomegalovirus. At present, the lowest infection rates in these patients may be achieved by careful control of immunosuppressive therapy, infection control procedures, rigid criteria for diagnosing rejection, and by monitoring patients with techniques that permit early identification of infection.