[Common infections in immunocompromised patients]

Immunocompromised patients are at increased risk for life-threatening as well as non life-threatening infectious complications. In contrast to the acutely granulocytopenic patient, the infectious syndromes occurring in other immunocompromised hosts are easily detected clinically. From a precise knowledge of the underlying specific host defense abnormality it is possible to predict the spectrum of the most likely causative organisms and the course of the infection. In the case of a defect in cell-mediated host defense, the variety of potential pathogens is wide and includes characteristically intracellular microorganisms. A defect in humoral immunity places patients at increased risk for infection due to encapsulated, extracellular organisms. Patients with qualitative defects of polymorphonuclear leukocyte defense are particularly susceptible to S. aureus infections. The lack of integrity of anatomical barriers (skin, mucous membranes) may lead to increased risk of localized or invasive infections by the colonizing microbial flora. Virtually every decision on antimicrobial therapy must be based upon careful evaluation of the integrity of all these host defense mechanisms. These relationships are illustrated by discussion of four infectious diseases: urinary tract infections, Candida mucositis, Varicella-Zoster virus infections and fever in the asplenic patient.