腎移植患者の真菌症

Abstract

Kidney transplantation therapy can be divided into two periods: the induction periods during which immunosuppressants are aggressively administered, and the maintenance periods during which treatment is continued at a maintenance dosage. During the induction periods, which usually lasts for several months after surgery, the host defense mechanism in the patient is so profoundly impaired that major infections, including deep-seated mycosis, occur in most cases. The incidence of mycosis as a result of superinfection was quite high in the l960s and l970s, when steroids and antimetabolites were the mainstay immunosuppressants, and antibacterial agents were used without any specific purpose for fear of post-transplantation infections. The new calcineurin inhibitor ciclosporin was developed around 1980 and has since become the primary immunosuppressant used to prevent graft dysfunction after transplantation. As a result of its advent, use of steroids and antimetabolites has declined. Later studies have shown that ciclosporin selectively inhibits lymphocytes and provides more information on the pattern of bacterial infections after transplantation, making it possible to optimize the use of antibacterial agents. As a result, the incidence of bacterial infections and mycosis has dramatically declined. Candida and Aspergillus are most frequently detected in post-transplantation mycosis. But Cryptococcus is also occasionally seen. Antifungal agents such as flucytosine (5-FC) and ketoconazole are effective for deep-seated mycosis such as pulmonary infections which, occurring at a relatively early stage after transplantation, threaten a patients life. However, the coadministration of ketoconazole must be carefully done because it increases blood concentrations of calcineurin inhibitors such as ciclosporin and tacrolimus by inhibiting the production of cytochrome P-450. Amphotericin B, which is effective but is associated with nephrotoxicity, is usually used in a mouthwash or inhalation therapy. Dermatomycosis such as tinea versicolor due to fragility of the skin structure is not necessarily rare even in patients with a quasi-normal host defense mechanism and good renal function at a late stage in the maintenance phase. This paper outlines change in post-transplantation mycosis in recent years and presents some case reports.