Pulmonary and Invasive Fungal Infections
Published Jan 30, 2020 · N. Clark
Seminars in Respiratory and Critical Care Medicine
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Abstract
The incidence of serious fungal infections has been increasing, and while invasive fungal infections are less frequently encountered in patients than those due to bacteria or viruses, their impact is significant. Invasive fungal infections are typically associated with a high rate of mortality, and their diagnosis and management are often challenging. Furthermore, there are newly emerging life-threatening fungal infections such as Candida auris, and the epidemiology of some fungal infections is changing, possibly due to alterations in climate and land use, as discussed in this issue. There is also a growing population of immunocompromised hosts at risk, including those living with acquired immunodeficiency syndrome (AIDS), transplant recipients, andpersons receivingone of the rapidly expanding numbers of biological agents indicated for the treatment of malignancy or inflammatory diseases of theskin, joints, orgastrointestinal tract. Therefore, clinicians need to be aware of these life-threatening infections and their most frequent manifestation, pneumonia. While advances in invasive fungal infection diagnostics have been modest, treatment has substantially changed with the introduction of less toxic and broader-spectrum antifungal medications such as the echinocandins and mold-active triazoles. This issue of Seminars in Respiratory and Critical Care Medicine reviews the epidemiology, diagnosis, treatment, and prevention of fungal infections that primarily involve the lungs. The first chapter of this issue by Drs. Gonzalez-Lara and Ostrosky-Zeichner discusses the most frequent health care associated invasive fungal infection, candidiasis. Candida species are among the top bloodstream pathogens, particularly among critically ill hospitalized persons who have had invasive procedures or devices. Rates of nonalbicans Candida species are increasing, and some of these have reduced susceptibility to azole antifungals. While Candida is not a usual pulmonary pathogen, disseminated infection can lead to infection of sterile sites such as the pleural cavity. The most common forms of fungal pneumonia in nonimmunocompromisedhosts are the endemic fungal infections histoplasmosis, blastomycosis, coccidioidomycosis, and paracoccidioidomycosis. Thefirst section of this issue is devoted to these infections. Some, such as histoplasmosis and blastomycosis, appear to have expanded their geographic reach. In addition, advances in phylogenetic testing have demonstrated new species designations (e.g., Blastomyces helicus [formerly Emmonsia helica] and Paracoccidioides americana, P. restrepiensis, and P. venezuelensis). All the endemic fungi may cause disease in immunocompetent individuals, but immunosuppressed individuals often experience more severe manifestations and disseminated infection. Drs. Monzon and Baddley provide a detailed discussion on cryptococcal disease caused by a globally distributed pathogen best known for its propensity to causemeningitis in AIDS patients. Given this predilection, the authors point out the need to search for extrapulmonary sites of infection when patients present with cryptococcal pneumonia. Management of central nervous system disease and the immune reconstitution syndrome that may be seen with cryptococcosis are reviewed, as is the emergence of Cryptococcus gattii, which, in some cases, may be associated with decreased susceptibility to azole antifungals. Aspergillosis is themost commonmold infection encountered in immunocompromised hosts, particularly thosewith prolonged neutropenia and/or exposure to chemotherapy, as well as recipients of hematopoietic stem cell transplantation and those receiving chimeric antigen receptor T-cell (CAR-T) therapy. As with other fungal pathogens, the taxonomy of Nina M. Clark, MD