Adiaspore development and morphological characteristics in a mouse adiaspiromycosis model.

Lesions of adiaspiromycosis, a respiratory disease affecting wild animals, have been found mainly in dead mammals and free-living mammals captured for surveillance. No report has described an investigation of adiaspore formation progress in the lung. After establishing an experimental mouse model of intratracheal adiaspiromycosis infection with the causative agent Emmonsia crescens, we observed adiaspore development. The spores grew and reached a plateau of growth at 70 days post-infection. The median adiaspore diameter showed a plateau of around 40 µm. The characteristic three-layer cell-wall structure of adiaspores was observed in the lung at 70 days post-infection. We examined infection with a few spores, which revealed that adiaspores in the mouse lung progressed from intratracheal infection of at least 400 spores. Moreover, we developed adiaspores in vitro by culture in fetal bovine serum. Although most spores broke, some large spores were intact. They reached about 50 µm diameter. Thick cell walls and dense granules were found as common points between in vitro adiaspores and in vivo adiaspores. These models are expected to be useful for additional investigations of E. crescens adiaspores and adiaspiromycosis.

Disseminated cutaneous chrysosporium infection.

Cutaneous chrysosporium infection is extremely rare and underdiagnosed. We present an immunocompromised patient who presented with recurrent cutaneous abscesses. Histopathology of the abscess showed thick-walled conidia and septate fungal hyphae within the subcutis and fungal culture grew Chrysosporium species.

Snake fungal disease: an emerging threat to wild snakes.

Since 2006, there has been a marked increase in the number of reports of severe and often fatal fungal skin infections in wild snakes in the eastern USA. The emerging condition, referred to as snake fungal disease (SFD), was initially documented in rattlesnakes, where the infections were believed to pose a risk to the viability of affected populations. The disease is caused by Ophidiomyces ophiodiicola, a fungus recently split from a complex of fungi long referred to as the Chrysosporium anamorph of Nannizziopsis vriesii (CANV). Here we review the current state of knowledge about O. ophiodiicola and SFD. In addition, we provide original findings which demonstrate that O. ophiodiicola is widely distributed in eastern North America, has a broad host range, is the predominant cause of fungal skin infections in wild snakes and often causes mild infections in snakes emerging from hibernation. This new information, together with what is already available in the scientific literature, advances our knowledge of the cause, pathogenesis and ecology of SFD. However, additional research is necessary to elucidate the factors driving the emergence of this disease and develop strategies to mitigate its impacts.This article is part of the themed issue 'Tackling emerging fungal threats to animal health, food security and ecosystem resilience'.

Intracellular colonization of Rhododendron and Vaccinium roots by Cenococcum geophilum, Geomyces pannorum and Meliniomyces variabilis.

Four in vitro experiments were set up to verify the colonization potential of ectomycorrhizal (EcM) Cenococcum geophilum FR. (strain CGE-4), saprotrophic Geomyces pannorum (LINK) SIGLER & CARMICHAEL (GPA-1) and a frequent root-associated, potentially ericoid mycorrhiza (ErM)-forming Meliniomyces variabilis Hambleton & Sigler (MVA-1) in roots of Rhododendron and Vaccinium. A typical ErM fungus, Rhizoscyphus ericae (Read) Zhuang & Korf (RER-1), was included for comparison. All fungal strains intracellularly colonized rooted Vaccinium microcuttings: GPA-1 occasionally produced hyphal loops similar to ErM, MVA-1 and RER-1 exhibited a typical ErM colonization pattern. CGE-4 hyphae grew vigorously on and around newly formed roots and rarely penetrated turgescent rhizodermal cells forming intracellular loose loops. Rooting of Rhododendron sp. microcuttings was not promoted by any fungal strain except CGE-4, which also promoted the most vigorous growth of Rhododendron ponticum L. seedlings. The widespread EcM fungus C. geophilum has a potential to colonize non-EcM roots and support their development which may influence overall growth of ericaceous plants. As shown for G. pannorum, structures resembling ErM may be formed by fungi that are to date not regarded as ericoid mycorrhizal.

Emmonsia crescens infection in a British water vole (Arvicola terrestris).

Emmonsia crescens, a dimorphic fungus of the order Onygenales, is primarily a pathogen of lower animals and rarely humans. Inhaled conidia of E. crescens fail to germinate in the lungs, and instead simply enlarge in lung tissue to become giant adiaspores. We present here the case of fatal Emmonsia crescens infection in a wild-caught British water vole (Arvicola terrestris). Histopathological examination of the animal, which died in captivity, revealed a multifocally extensive granulomatous reaction containing oval adiaspores scattered irregularly throughout the lungs. Mycological examination of fungus cultured from lung tissue and PCR amplification and sequencing of rDNA gene fragments of the cultured organism confirmed the diagnosis of massive infection by E. crescens.

Role of Chrysosporium keratinophillum in the parasitic evolution of dermatophytes.

Anti-dermatophytic activity of Chrysosporium keratinophillum against species of the genera Trichophyton, Microsporum and Epidermophyton floccosum was tested in vitro. When C. keratinophillum and different species of dermatophytes were inoculated on Sabouraud's dextrose agar plates 2 cm apart, no antagonistic effect of C. keratinophillum on the mycelial growth of dermatophytes was observed. However, conidia production was not observed on the hyphae of Trichophyton rubrum, Trichophyton tonsurans and E. floccosum grown near C. keratinophillum. The secretory substances released by C. keratinophillum inhibited the growth of T. rubrum, T. tonsurans, Trichophyton mentagrophytes var. interdigitale and E. floccosum at a concentration of 2,000 microg ml(-1) when tested by broth dilution technique. No inhibition of the growth was observed for Microsporum gypseum and Microsporum nanum. The anti-fungal activity of secretory substances released by C. keratinophillum was recorded to be heat stable. Results of the present study suggest that the anti-dermatophytic activity of the secretory substances of C. keratinophillum on T. rubrum, T. mentagrophytes var. interdigitale, T. tonsurans and E. floccosum may be responsible in part, for the absence of these dermatophyte species in soil. Considering the global prevalence of C. keratinophillum in soil one may speculate that the anti-dermatophytic activity of C. keratinophillum is one of the early events for the evolutionary divergence of saprophytic archi-dermatophytes to obligate parasitic dermatophyte species.

Chrysosporium chiropterorum sp. nov., isolated in France, resembling Chrysosporium state of Ajellomyces capsulatus (Histoplasma capsulatum).

A fungus isolated in France from the fur of a bat, which produces characterized large tuberculate conidia (aleurioconidia) similar to those produced by the mycelial form of Histoplasma capsulatum (Ajellomyces capsulatus) is described. Colonies are white at first, but then become rosy buff from the centre outwards. Sectoring, resulting in the appearance of patches or areas of dark green mycelium, occurs spontaneously. Single-celled conidia are formed on undifferentiated hyphae, and may be sessile, or borne laterally on short stalks or producing in an intercalary position as it is the case in the genus Chrysosporium. This fungus is clearly distinguishable from any described species and is described as Chrysosporium chiropterorum sp. nov. C. chiropterorum, like H. capsulatum, produces gelatinase, and is non-keratinolytic but strongly ureolytic. Both species are associated with bat dwellings. C. chiropterorum differs from H. capsulatum by faster growth, pink or green colonies, and failure to produce microconidia as well as lack of conversion to a yeast phase in vitro at 37 degrees C.

Did earthworms contribute to the parasitic evolution of dermatophytes?

The survival of dermatophyte species in the gut of four species of earthworms was studied by feeding the fungi to the earthworms. Recovery of the dermatophyte species in culture from the guts was only possible for Microsporum gypseum and Chrysosporium keratinophilum. In the light of these findings, we presume that earthworms could have influenced the parasitic evolution of certain dermatophytes.

Ajellomyces crescens sp. nov., taxonomy of Emmonsia spp., and relatedness with Blastomyces dermatitidis (teleomorph Ajellomyces dermatitidis).

Adiaspiromycosis is known primarily as a pulmonary infection of small burrowing mammals and rarely of humans, in which the tissue spore form consists of a large, globose, thick-walled, non-proliferating structure called an adiaspore. The causative agents have been placed in Emmonsia or Chrysosporium and treated as either two species or varieties. Emmonsia parva (= Chrysosporium parvum var. parvum) has been distinguished from E. crescens (= C parvum var. crescens) by differences in maximum growth temperature, size of adiaspores, host range and geographical distribution. Phenotypic similarities between Emmonsia spp. and Blastomyces dermatitidis and chance observation of Ajellomyces-type ascomatal hyphae led to the hypothesis that the teleomorph of Emmonsia spp. could occur in Ajellomyces. Isolates preliminarily identified as E. parva or E. crescens were examined by morphology and physiology and tested for compatibility in mating experiments. Ajellomyces crescens Sigler sp. nov. is described for the teleomorph of Emmonsia crescens based on compatibility among 12 of 22 strains, stellate gymnothecial ascomata composed of obtuse diamond-shaped cells, helically coiled appendages and small, globose, muriculate ascospores. The agents of adiaspiromycosis are here treated as species with adiaspore size and morphology and temperature of induction as their major defining features. The species differ also in cycloheximide tolerance and in their abilities to form a teleomorph. With evidence of a connection between Emmonsia crescens and a teleomorph in Ajellomyces, Emmonsia is favoured over Chrysosporium as the correct name for the agents of adiaspiromycosis. This finding also corroborates earlier suggestions of a close phylogenetic relationship between Emmonsia spp. and the dimorphic pathogens Blastomyces dermatitidis and Histoplasma capsulatum.

Influence of water activity and temperature on survival of and colony formation by heat-stressed Chrysosporium farinicola aleuriospores.

The ability of sublethally heat-stressed aleuriospores of Chrysosporium farinicola to form colonies on yeast extract-glucose agar (YGA) supplemented with sufficient glucose, sorbitol, glycerol, and NaCl to achieve reduced water activity (aw) in the range of 0.88 to 0.95 was determined. The effects of the aw of diluent and incubation temperature during recovery and colony formation were also investigated. Aleuriospores harvested from 14-day-old cultures grown at 25 degrees C were less resistant to heat inactivation compared with aleuriospores from 20-day-cultures. Increased populations of heat-stressed aleuriospores were recovered as the aw of YGA was decreased from 0.95 (glucose and glycerol) and 0.94 (sorbitol) to 0.89 and 0.88, respectively. In NaCl-supplemented YGA, populations recovered at an aw of 0.94 were greatly reduced compared with populations detected at an aw of 0.92; no colonies were formed on NaCl-supplemented YGA at an aw of 0.88. Tolerance to aw values above 0.88 to 0.89 as influenced by solute type was in the order of glucose greater than sorbitol greater than glycerol greater than NaCl. Incubation at 20 degrees generally resulted in an increase in recoverable aleuriospores compared with incubation at 25 degrees C or at 30 degrees C for 14 days followed by 20 degrees C for 10 days. The lethal effect of NaCl on heat-stressed aleuriospores was enhanced at 30 degrees C. The retention of viability of aleuriospores held in sucrose-peptone water diluent (aw, 0.936) for 20 min was essentially the same as that observed when aleuriospores were held in peptone water (aw, 0.997).(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of animal hibernation on the development of mycoses.

The development of adiaspiromycosis and trichophytosis depending upon the state of activity of red-cheeked squirrels is described. The conidia of Chrysosporium (Emmonsia) parvum var. crescens, are not transformed into adiaspores when injected into hibernating animals. During the hibernation period of four months, most of the conidia die. After awakening, the remaining viable conidia are transformed into adiaspores. During hibernation the squirrels, which had been infected with Trichophyton mentagrophytes var. granulosum, developed a symptom-free infection.

[Adiaspiromycosis--a little known lung disease]. / Ubersichtsarbeit.

Adiaspiromycosis produced by the fungus Emmonsia crescens is a pulmonary disease afflicting primarily small wild mammals. Man, too, may become an accidental link of the saproparatrophic circulation of the agent. Humans are infected--similarly to other mammals--by inhaling the elements of the saprophytic stage of the fungus living for long time periods in the soil substrates. After the infecting cells, aleuriospores, have invaded the host lungs, they are converted into the elements of the parasitic stage--adiaspores. These are surrounded by granulomatous tissue and reach up to 700 microns in diameter. In the circulation of the agent, the infected wild mammals play a role of reservoir hosts harbouring the parasitic stage of the fungus in nature for a relatively long time. In some cases these animals also enable spread of adiaspiromycosis from exoanthropic foci into human habitations. Clinical and experimental studies show that the result of an infection may be--in addition to its liquidation--an asymptomatic form of disease or a disseminated pulmonary process. In addition to as yet insufficiently proved proper action of fungus cells, a reduction in the functional pulmonary parenchyma plays a role in the pathogenesis of the pulmonary forms. An existence of extrapulmonary forms of adiaspiromycosis is not excluded. Serological methods have not been routinely used for diagnosis as yet: immune reaction of the organism has a character of antibody response and delayed hypersensitivity. Cell mediated immunity has not been studied as yet. Treatment of human disease is primarily a surgical one. The fungistatic drugs pimaricin or amphotericin B may be employed, corticosteroids may be indicated in individual cases. The efficacy of modern antifungal substances has not been established as yet.

Adiaspiromycosis.

We have then a disease that, for many years (since 1942), was known only to infect lower animals; after a sporadic encapsulated adiaspore was observed by Doby-Dubois in 1964 in a patient's lung, a widely disseminated, clinically symptomatic case was reported from Czechoslovakia, rapidly followed by three mildly disseminated cases, one from Russia and two from Guatemala, with innumerable granulomas similar to the patient of Kodousek et al. patient. Alert observers contributed descriptions of single adiaspores in arrested granulomas of the lung. The finding of presumed adiaspores in the lumen of an appendix seems unique. The reaction to the adiaspores is a tubercular granuloma, with fibroblast, (few) epithelioid, and giant cells representing the main component of the tissue response. Most observers agree on the absence of necrosis--one reason why the lesions do not calcify. The natural history of the disease seems to be self-limited, even if the extent of the involvement of the lung parenchyma determines the gravity of symptoms. The sudden flurry of reports makes it likely that cases previously had been mistaken for C. immitis or infestation by parasites.

Avirulence and decreased virulence in mutants of Emmonsia crescens, a causative agent of adiaspiromycosis.

Three mutants of Emmonsia crescens with altered morphology and pathogenicity for mice are described. The mutant M-1 is avirulent and does not form adiaspores of normal morphology on agar medium at 37 degree C. The mutants M-2 and M-12 have a considerably decreased virulence. The pathogenicity of E. crescens depends on the ability to differentiate adiaspores of perfect morphology. The loss of virulence and the decrease of virulence of mutants seem to be caused by the pleiotrophic effect of mutation of the genetic base, which regulates the differentiation of adiaspores. The conidia of the wild strain of E. crescens killed by UV-irradiation do not induce the formation of granulomas with adiaspores after i.p. inoculation into mice.