Emerging and reemerging fungal infections

Abstract

Fungal infections throughout the world appear to be increasing. This may in part be due to the increase in the population of patients that are susceptible to otherwise rare fungal infections resulting from the use of immune modulating procedures such as hematopoietic stem cell transplants and drugs like tissue necrosis factor antagonists. Histoplasma capsulatum, an endemic fungus throughout North and South America, is reemerging among HIV+ patients in Central and South America and among patients taking tissue necrosis factor antagonists and other biologics in North America. Fusarium species, a relatively rare fungal infection, is reemerging worldwide in the immunocompromised populations, especially those who are neutropenic like hematopoietic stem cell transplant recipients. A new yeast species is currently emerging worldwide: Candida auris, unknown just a decade ago. It is causing large healthcare-associated outbreaks on four continents and is spreading throughout the world through patient travel. In this review the epidemiology, pathology, detection and treatment of these three emerging and reemerging fungi will be discussed.

Keywords: Candida auris; Fungi; Fusarium; Histoplasma.

Fig. 1.

Case of disseminated histoplasmosis in skin and bone marrow. A: Skin with mononuclear inflammatory infiltrate in the upper dermis (hematoxylin and eosin stain, original magnification 100×). B: Higher magnification (250×) of hematoxylin and eosin stain showing macrophages filled up with Histoplasma. C: Grocott methenamine silver stain highlighting the Histoplasma inside the macrophages from the bone marrow biopsy (original magnification 250×). D: Macrophage with multiple Histoplasma from the bone marrow aspirate (Giemsa stain, original magnification 250×).

Fig. 2.

Case of disseminated fusariosis. A: Gram stain of blood culture showing abundant hyphae (original magnification 250×). B: Skin with petechial hemorrhages in the upper dermis (hematoxylin and eosin stain, original magnification 25×). C: Higher magnification (250×) of hematoxylin and eosin stain showing single hyaline hyphae with one septum inside a blood vessel in the upper dermis. D. Grocott methenamine silver stain highlighting abundant septated hyphae in the sinus debridement specimen from the same patient.