Corticosteroids, cytotoxic agents, and infection

Iatrogenic immunosuppression can be achieved using corticosteroids or noncorticosteroid a gents. Although there is considerable overlap, noncorticosteroid immunosuppressants can be broadly divided into those that are primarily cytotoxic antineoplastic drugs and those that are used primarily in transplantation. Advances in immunosuppressive therapy have greatly decreased morbidity and mortality attributable to transplantation rejection and autoimmune diseases, but the cellular targets of immunosuppressive agents are frequently the cornerstones of the body's defenses against pathogenic microorganisms. As a result of this double-edged action, the use of immunosuppressants involves walking a fine line between therapy and iatrogenic harm. Indeed, with the advent of powerful immunosuppressive agents, there has been an emergence of a wider spectrum of infections. The specific type of agent, the dosage used, the length of therapy, and the underlying disease process all affect the incidence and type of infectious complication likely to occur with immunosuppressive therapy. Understanding the mechanism of action of these agents will aid in determining the appropriate immunization/prophylaxis, and in choosing the appropriate empiric therapy in patients with signs of infection.