[Infectious complications due to immunosuppression in organ transplant patients]

Prevention and treatment of allograft rejection by immunosuppressive treatments expose organ transplant patients to frequent and sometimes severe infectious complications. Immunosuppressive drugs inhibit both the immune response to alloantigens, and the anti-infectious immunity; they promote intracellular infections, including infections with viruses and with bacterial, parasitic and mycotic agents. Infectious risks are related to duration of immunosuppression exposure, type of immunosuppressive drugs, combination of drugs and trough levels required to control rejection. Assessment of the risk of infectious diseases in transplant patients before transplantation has to take into account past medical history, number of previous transplantations, immunosuppressive regimen, and the risk of infectious diseases transmitted from the donor. After the graft, infectious risks have to be assessed by clinical examination, repeated white blood cell count to detect leucopenia. In high risk population, monitoring for CMV and EBV infections is based on analysis of replication using nucleic acid based assays or antigenemia studies. Prophylactic anti-infectious therapy in high-risk patients has resulted in reduction of the consequences of overimmunosuppression in organ transplantation.