Ecology of aspergillosis: insights into the pathogenic potency of Aspergillus fumigatus and some other Aspergillus species

Abstract

SummaryFungi of the genus Aspergillus are widespread in the environment. Some Aspergillus species, most commonly Aspergillus fumigatus, may lead to a variety of allergic reactions and life‐threatening systemic infections in humans. Invasive aspergillosis occurs primarily in patients with severe immunodeficiency, and has dramatically increased in recent years. There are several factors at play that contribute to aspergillosis, including both fungus and host‐related factors such as strain virulence and host pulmonary structure/immune status, respectively. The environmental tenacity of Aspergilllus, its dominance in diverse microbial communities/habitats, and its ability to navigate the ecophysiological and biophysical challenges of host infection are attributable, in large part, to a robust stress‐tolerance biology and exceptional capacity to generate cell‐available energy. Aspects of its stress metabolism, ecology, interactions with diverse animal hosts, clinical presentations and treatment regimens have been well‐studied over the past years. Here, we synthesize these findings in relation to the way in which some Aspergillus species have become successful opportunistic pathogens of human‐ and other animal hosts. We focus on the biophysical capabilities of Aspergillus pathogens, key aspects of their ecophysiology and the flexibility to undergo a sexual cycle or form cryptic species. Additionally, recent advances in diagnosis of the disease are discussed as well as implications in relation to questions that have yet to be resolved.

Salpingopharyngeal fistula as a treatment for guttural pouch mycosis in seven horses

“…It is speculated by the authors that a salpingopharyngeal fistula would negatively affect fungal growth. While there is no direct evidence to support that premise at this time, Aspergillus fumigatus grows well at 37°C and is best adapted to microenvironments of the body that are often characterised by low nutrient and oxygen availability . These factors may be consistent with the microenvironment of the guttural pouch prior to fistulation.…”

Characterization of Aspergillus fumigatus Isolates from Air and Surfaces of the International Space Station

“…As such, stress tolerance may play a more dominant role in the ability of A. fumigatus to colonize harsh niches. Given that the stress response pathways of A. fumigatus are unarguably involved in this organism’s environmental ubiquity and its leading position as an opportunistic pathogen (18, 45, 46), it is still unclear how existing genetic heterogeneity plays a role in stress tolerance. While limited in scope, we found no enhanced ability of the ISS strains over Af293 and CEA10 to tolerate a diversity of chemical stresses (Fig.…”

“…Globally encountered in soil and air, A. fumigatus is well adapted to colonizing diverse environments through its metabolic diversity, broad stress and thermal tolerances, and easily dispersed conidia (18–20). Likely underlying the ubiquity and pathogenic capacity of A. fumigatus is a great degree of genetic diversity observed among strains from diverse environmental and clinical sources (21–23).…”

Comparative Evaluation of in Vitro Virulence of Mould Isolates from Clinical Cases and from Air Samples and Their Mortality Rates in Galleria mellonella Larvae

“…Virülansları düşük olduğu için, dermatofitler dışındaki küf mantarlarının infeksiyon oluşturabilmeleri konak faktörlerine bağlıdır. Küf mantarlarının sahip olduğu virü-lans faktörleri hücre dışı enzimleri, bazı toksinleri, melanin üretimleri, siderofor içermeleri, hücre duvarındaki antijenik yapılar, konidyaları-nın şekli, solunum hücrelerine girebilme özellik-leri ve konak faktörlerine gösterdikleri dirençtir (1)(2)(3) . Küf mantarlarının in vitro virülans özelliklerinin irdelendiği sınırlı sayıda çalışma bulunmaktadır.…”

“…Ancak, enfeksiyon etkeni küfler daha çok Aspergillus cinsi ve Mucoromycotina üyeleridir (4) . Havadan izole edilen bir Aspergillus kökeni ile enfeksiyon etkeni olan bir başka Aspergillus kökeni arasın-daki virülans farkının araştırıldığı az sayıda yayın bulunmaktadır (1) . Mantarların virülans faktörleri genellikle maya mantarları ve en çok da Candida cinsi ile çalışılmıştır (5) .…”