Diagnosis and Prevention of Invasive Fungal Infections in the Immunocompromised Host

Topic importance: The prevalence of invasive fungal infections (IFIs) has risen in the past 3 decades, attributed to advancements in immune-modulatory therapies used in transplantation, rheumatology, and oncology.

Review findings: Organisms that cause IFI evade the host's natural defenses or at opportunities of immunologic weakness. Infections occur from inhalation of potentially pathogenic organisms, translocation of commensal organisms, or reactivation of latent infection. Organisms that cause IFI in immunocompromised populations include Candida species, Cryptococcus species, environmental molds, and endemic fungi. Diagnosis of these infections is challenging due to slow organism growth and fastidious culture requirements. Moreover, fungal biomarkers tend to be nonspecific and can be negatively impacted by prophylactic antifungals. Antibody-based tests are not sensitive in immunocompromised hosts making antigen-based testing necessary. Risk reduction of IFI is guided by pathogen avoidance, removal or minimization of immune-suppressing factors, and pharmacologic prophylaxis in select hosts.

Summary: Understanding the complex interplay between the immune system and opportunistic fungal pathogens plays a key role in early diagnosis and prevention.