INTRODUCTION

Among the most formidable challenges to the clinician is the care of the patient with an impaired immune system – the compromised host. The growing number of organ transplant recipients has created a heightened need to characterize the infections of patients on chronic immunosuppression. For instance, in the United States, in the year 2005 alone, 28,000 transplants were performed. The success of the solid organ transplantation is incumbent on the success of our management of improved immunosuppressive therapies and our ability to recognize and control infections. Two characteristics of the compromised host, in particular, contribute to the complexity of management of infection in these patients: (1) the exceptionally broad variety of potential microbial pathogens and (2) the wide spectrum of clinical manifestations of disease resulting from the abnormal immune response.

In the compromised patient, cutaneous and subcutaneous tissues may be expected to be an important focus of infection, for three reasons. First, the skin, together with the mucosal surfaces, represents the first line of defense of the body against the external environment. These barriers assume an even greater importance when secondary defenses, such as phagocytosis, cell-mediated immunity, and antibody production, are impaired. Second, the rich blood supply of the skin provides a route of spread of infection, both from the skin to other body locations and to the skin from other sites of infection.