Pathogenicity &amp; virulence of <i>Histoplasma capsulatum</i> - A multifaceted organism adapted to intracellular environments

Valdez, Alessandro F.; Miranda, Daniel Zamith; Guimarães, Allan J.; Nimrichter, Leonardo; Nosanchuk, Joshua D.

doi:10.1080/21505594.2022.2137987

Cited by 20 publications

(20 citation statements)

References 183 publications

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“…Once in the alveoli, H. capsulatum evades the soluble pattern-recognition receptors, collectins (surfactant protein A and surfactant protein D), and rapid internalization into macrophages. Yeasts can be internalized by other phagocytes, including dendritic cells, neutrophils, and natural killer cells, but are incapable of surviving within them [ 11 ].…”

Section: Pathogenesismentioning

confidence: 99%

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Pulmonary Histoplasmosis: A Clinical Update

Barros

Wheat²,

Hage

2023

JoF

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Histoplasma capsulatum, the etiological agent for histoplasmosis, is a dimorphic fungus that grows as a mold in the environment and as a yeast in human tissues. The areas of highest endemicity lie within the Mississippi and Ohio River Valleys of North America and parts of Central and South America. The most common clinical presentations include pulmonary histoplasmosis, which can resemble community-acquired pneumonia, tuberculosis, sarcoidosis, or malignancy; however, certain patients can develop mediastinal involvement or progression to disseminated disease. Understanding the epidemiology, pathology, clinical presentation, and diagnostic testing performance is pivotal for a successful diagnosis. While most immunocompetent patients with mild acute or subacute pulmonary histoplasmosis should receive therapy, all immunocompromised patients and those with chronic pulmonary disease or progressive disseminated disease should also receive therapy. Liposomal amphotericin B is the agent of choice for severe or disseminated disease, and itraconazole is recommended in milder cases or as “step-down” therapy after initial improvement with amphotericin B. In this review, we discuss the current epidemiology, pathology, diagnosis, clinical presentations, and management of pulmonary histoplasmosis.

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Section: Pathogenesismentioning

confidence: 99%

“…In addition, the H antigen is a beta-glucosidase that remodels the yeast cell wall and is involved in nutrient acquisition [ 13 ]. Altogether, the Hsp60-CR3 engagement, while avoiding dectin-1, leads to yeast internalization without triggering pro-inflammatory cascades [ 11 ].…”

Section: Pathogenesismentioning

confidence: 99%

Pulmonary Histoplasmosis: A Clinical Update

Barros

Wheat²,

Hage

2023

JoF

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“…To infect and cause disease in healthy humans, true pathogenic fungi should meet four basic criteria: (i) growth at elevated human body temperatures, (ii) bypassing around or penetrating through surface host barriers, (iii) secretion of lytic enzymes for acquiring nutrients from the host tissues, and (iv) evasion or resistance to the host's immune defense systems. The fungi that infect previous healthy humans represent a small group, many more invasive fungal infections now occurring in patients with underlying serious illnesses [15,17].…”

Section: Figurementioning

confidence: 99%

“…The fungus is characterized as a primary pathogen because of its ability to cause infection both in previous healthy individuals and immunocompromised hosts and systemic for its tendency to involve deep viscera after dissemination from the lungs [17,41].…”

Section: Characteristics Of H Capsulatummentioning

confidence: 99%

“…In 95% of immunocompetent individuals, the infection with H. capsulatum evolves usually benign and asymptomatic. Histoplasmosis is life-threatening particularly in immunocompromised patients, clinical manifestations, and the prognosis of the disease depending on the size inoculum and virulence of the infecting strain [17]. Since the beginning of HIV pandemic in 1980s, histoplasmosis has also been considered an AIDS-defining illness starting with 1987 [43][44][45].…”

Section: Characteristics Of H Capsulatummentioning

confidence: 99%

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Epidemiology of Histoplasmosis

Efrim¹,

Dumea²,

Cernat³

2023

Infectious Diseases

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More prevalent than initially considered, histoplasmosis is primarily a non-contagious disease of the reticuloendothelial system, producing a broad spectrum of clinical manifestations, ranging from asymptomatic or self-limited infection, in immunocompetent patients to life-threatening, disseminated disease in immunocompromised ones. The causative agent is H. capsulatum, a thermally dimorphic, intracellular fungus, discovered in 1906, by the pathologist Samuel Darling, when examined tissues from a young man whose death was mistakenly attributed to miliary tuberculosis. Since then, histoplasmosis was described on six continents, with high and low endemicity areas. H. capsulatum is a soil-based fungus, commonly associated with river valleys in the temperate zone, and with the presence of bird and bat guano. Infection occurs when saprophytic spores are inhaled and change to the pathogenic yeast in the lungs, where H. capsulatum overcomes many obstacles to cause host injuries. Depending on geographic distribution, morphology, and clinical symptoms, three varieties have been historically recognized, two of them (var. capsulatum and var. duboisii) being pathogen to humans, and the third (var. farciminosum) has predominantly been described as an equine pathogen. In endemic areas, patients with AIDS or people who receive immunosuppressive therapies should be counseled to avoid high-risk activities; otherwise, precautionary measures should be taken.

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