Fungal Infections in Immunosuppressed Patients

Fungal infections, also called mycoses, are important causes of morbidity and mortality in humans. Some fungal infections are endemic, and these infections are usually caused by fungi that are present in the environment and whose spores enter humans. Other fungal infections are said to be opportunistic because the causative agents cause mild or no disease in healthy individuals but may infect and cause severe disease in immunodeficient persons. The human airway is continuously open to the nonsterile environment where fungal spores have the potential to reach lung tissue and produce disease. In the immunocompromised host, many fungi, including species of fungi typically considered nonpathogenic, have the potential to cause serious morbidity and mortality. Over the last several decades the advent of the human immunodeficiency virus (HIV) epidemic and the increasing use of immunosuppressive drugs for serious medical conditions have dramatically increased the number of persons who are severely immunocompromised. In addition, the range and diversity of fungi that cause disease have broadened. Although Candida and Aspergillus species continue to be the fungal pathogens that most frequently cause invasive fungal disease in immunocompromised persons overall, infections due to previously uncommon hyaline and dematiaceous filamentous fungi are being reported with increasing frequency. This is significant because, despite marked advances in antifungal therapy, infections caused by opportunistic fungal infections (rare and emerging) continue to be associated with high morbidity, high mortality, and poor patient outcomes. This results from a combination of drug-resistant strains, lack of robust clinical studies evaluating treatments, and severe underlying diseases in the patient [2].