In vitro effect of Chrysosporium indicum and Chrysosporium keratinophylum on Toxocara canis eggs

The degree of antagonism exercised by fungi on geohelminth development varies according to the morphological alterations caused by different fungal species. Saprophytic fungi may exert ovicidal or ovistatic effects. The aim of this study was to apply scanning electron microscopy (SEM) to observe the action of two soil saprophytic species of Chrysosporium (C. indicum and C. keratinophylum) on Toxocara canis eggs. The fungal strains to be tested were incubated for 28 days at 28°C in 2% water agar with a suspension of unembryonated T. canis eggs. A suspension of T. canis eggs in 2% water agar was used as control group. The assay was done in triplicate for each fungus and the control group. SEM observations were performed on the 4th, 7th, 14th, 21st, and 28th day after inoculation. The effect of the fungi on eggs was evaluated in accordance with the alterations observed on the surface and the changes in the normal characteristics of the eggs. Hyphae around the eggs, appresoria penetrating the shell and changes in the typical egg membrane were observed in this assay. Type 3 effect (alterations that occur both in the embryo and the shell, and hyphal penetration of the eggs) was the prevalent effect. SEM allowed us to observe clearly the morphological alterations in T. canis eggs due to the effect of C. indicum and C. keratinophylum. Both saprophytic species of Chrysosporium alter the egg structure and alterations increase as exposure increases.

The Dynamic Genome and Transcriptome of the Human Fungal Pathogen Blastomyces and Close Relative Emmonsia

Three closely related thermally dimorphic pathogens are causal agents of major fungal diseases affecting humans in the Americas: blastomycosis, histoplasmosis and paracoccidioidomycosis. Here we report the genome sequence and analysis of four strains of the etiological agent of blastomycosis, Blastomyces, and two species of the related genus Emmonsia, typically pathogens of small mammals. Compared to related species, Blastomyces genomes are highly expanded, with long, often sharply demarcated tracts of low GC-content sequence. These GC-poor isochore-like regions are enriched for gypsy elements, are variable in total size between isolates, and are least expanded in the avirulent B. dermatitidis strain ER-3 as compared with the virulent B. gilchristii strain SLH14081. The lack of similar regions in related species suggests these isochore-like regions originated recently in the ancestor of the Blastomyces lineage. While gene content is highly conserved between Blastomyces and related fungi, we identified changes in copy number of genes potentially involved in host interaction, including proteases and characterized antigens. In addition, we studied gene expression changes of B. dermatitidis during the interaction of the infectious yeast form with macrophages and in a mouse model. Both experiments highlight a strong antioxidant defense response in Blastomyces, and upregulation of dioxygenases in vivo suggests that dioxide produced by antioxidants may be further utilized for amino acid metabolism. We identify a number of functional categories upregulated exclusively in vivo, such as secreted proteins, zinc acquisition proteins, and cysteine and tryptophan metabolism, which may include critical virulence factors missed before in in vitro studies. Across the dimorphic fungi, loss of certain zinc acquisition genes and differences in amino acid metabolism suggest unique adaptations of Blastomyces to its host environment. These results reveal the dynamics of genome evolution and of factors contributing to virulence in Blastomyces.

Dimorphic fungal pathogens including Blastomyces are the cause of major fungal diseases in North and South America. The genus Emmonsia includes species infecting small mammals as well as a newly emerging pathogenic species recently reported in HIV-positive patients in South Africa. Here, we synthesize both genome sequencing of four isolates of Blastomyces and two species of Emmonsia as well as deep sequencing of Blastomyces RNA to draw major new insights into the evolution of this group and the pathogen response to infection. We investigate the trajectory of genome evolution of this group, characterizing the phylogenetic relationships of these species, a remarkable genome expansion that formed large isochore-like regions of low GC content in Blastomyces, and variation of gene content, related to host interaction, among the dimorphic fungal pathogens. Using RNA-Seq, we profile the response of Blastomyces to macrophage and mouse pulmonary infection, identifying key pathways and novel virulence factors. The identification of key fungal genes involved in adaptation to the host suggests targets for further study and therapeutic intervention in Blastomyces and related dimorphic fungal pathogens.

A dimorphic fungus causing disseminated infection in South Africa

BACKGROUND

The genus emmonsia contains three species that are associated with human disease. Emmonsia crescens and Emmonsia parva are the agents that cause adiaspiromycosis, and one human case of Emmonsia pasteuriana infection has been described. We report a fungal pathogen within the genus emmonsia that is most closely related to E. pasteuriana in human immunodeficiency virus (HIV)-infected adults in South Africa.

METHODS

Between July 2008 and July 2011, we conducted enhanced surveillance to identify the cause of systemic, dimorphic fungal infections in patients presenting to Groote Schuur Hospital and other hospitals affiliated with the University of Cape Town, Cape Town, South Africa. DNA sequencing was used to identify pathogenic fungi.

RESULTS

A total of 24 cases of dimorphic fungal infection were diagnosed, 13 of which were caused by an emmonsia species. All 13 patients were HIV-infected, with a median CD4+ T-cell count of 16 cells per cubic millimeter (interquartile range, 10 to 44), and all had evidence of disseminated fungal disease. Three patients died soon after presentation, but the others had a good response to a variety of antifungal agents and antiretroviral therapy. Phylogenetic analysis of five genes (LSU, ITS1-2, and the genes encoding actin, β-tubulin, and intein PRP8) revealed that this fungus belongs in the genus emmonsia and is most closely related to E. pasteuriana.

CONCLUSIONS

The findings suggest that these isolates of an emmonsia species represent a new species of dimorphic fungus that is pathogenic to humans. The species appears to be an important cause of infections in Cape Town.

Pathogenicity of the Chrysosporium anamorph of Nannizziopsis vriesii for veiled chameleons (Chamaeleo calyptratus)

Veiled chameleons (Chamaeleo calyptratus) were experimentally challenged with the fungus Chrysosporium anamorph of Nannizziopsis vriesii (CANV). Chameleons were exposed to conidia in their captive environment, or were inoculated by direct application of a conidial suspension inoculum on intact and on abraded skin. The CANV induced lesions in all experimental groups and was recovered from infected animals, fulfilling Koch's postulates and confirming that it may act as a primary fungal pathogen in this species of reptile. A breach in cutaneous integrity, as simulated by mild scarification, increased the risk of infection but was not required for the CANV to express pathogenicity. Initial hyphae proliferation occurred in the outer epidermal stratum corneum, with subsequent invasion of the deeper epidermal strata and dermis. A spectrum of lesions was observed ranging from liquefactive necrosis of the epidermis to granulomatous inflammation in the dermis. CANV dermatomycosis appears to be contagious and can readily spread within a reptile collection, either directly through contact with infective arthroconidia or indirectly via fomites. Dense tufts of arthroconidiating hyphae were demonstrated histologically on the skin surface of many animals that developed dermatomycosis, and these arthroconidia may act as infective propagules involved in the transfer of disease between reptiles.

Emmonsia crescensinfection 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.

Yeast tissue phase of Emmonsia pasteuriana inoculated in golden hamster by intratesticular way

The scope of our study was to present an experimental model reproducing the dimorphic yeast-like population (as for Histoplasma capsulatum, Blastomyces dermatitidis) similar to that observed in the cutaneous biopsy of an Italian woman who had never traveled abroad, being intravenous drug user and HIV positive for 10 years, finally infected with the new dimorphic fungus Emmonsia pasteuriana. Experimental inoculation was unsuccessful by intraperitoneal (i.p.) and intravenous (i.v.) ways in a mouse and in a guinea-pig model inoculated by cutaneous or subcutaneous routes, reason for that we chose the golden hamster, highly sensitive to dimorphic fungi as agents of systemic mycoses as histoplasmosis, blastomycosis, sporotrichosis, penicilliosis marneffei, paracoccidioidomycosis when the inoculation was done by intraperitoneal route. We inoculated young golden hamsters by i.p. and intratesticular ways. Only by this last route we reproduced an orchiepididymitis with necrosis, haemorrhages and a polymorphic yeast-like population similar to the polymorphism observed in the cutaneous biopsy of the patient. The intratesticular affinity of E. pasteuriana provided an interesting model for this infection.

Disseminated infection due to Chrysosporium zonatum in a patient with chronic granulomatous disease and review of non-Aspergillus fungal infections in patients with this disease

We report the first case of Chrysosporium zonatum infection in a 15-year-old male with chronic granulomatous disease who developed a lobar pneumonia and tibia osteomyelitis while on prophylaxis with gamma interferon. The fungus was isolated from sputum and affected bone, and hyphae were observed in the bone by histopathology. Therapy with amphotericin B eradicated the osteomyelitis and pneumonia, but pneumonia recurred in association with pericarditis and pleuritis during therapy with itraconazole. These manifestations subsided, and no recurrences occurred with liposomal amphotericin B therapy. Infections caused by Chrysosporium species are very rare, and C. zonatum has not previously been reported to cause mycosis in humans. This species, the anamorph of the heterothallic ascomycete Uncinocarpus orissi (family Onygenaceae), is distinguished by its thermotolerance, by colonies which darken from yellowish white to buff, and by club-shaped terminal aleurioconidia borne at the ends of short, typically curved stalks. The case isolate produced fertile ascomata in mating tests with representative isolates. The median (range) MICs for our isolate as well as those for two other human isolates and a nonhuman isolate determined by the National Committee for Clinical Laboratory Standards method adapted for moulds were </=0.06 microg/ml (</=0.06 to 0.25 microg/ml) for amphotericin B, 0. 687 microg/ml (0.25 to 2 microg/ml) for itraconazole, >128 microg/ml (>128 microg/ml) for flucytosine, and 48 microg/ml (32 to >128 microg/ml) for fluconazole.

Chrysosporium tropicum as a probable cause of mycosis of poultry in India

Chrysosporium tropicum was isolated from comb lesions in two different breeds of chickens in India and subcultures were shown to be pathogenic when inoculated onto prepared skin of guinea pigs. This report provides additional evidence to consider Ch. tropicum as a pathogenic fungus and a probable cause of a dermatomycosis in chickens.

Pathogenicity of some Chrysosporium species isolated in France

In order to appreciate the pathogenicity of several geophilic Chrysosporium species (including Anixiopsis stercoraria, Chrysosporium keratinophilum, C. tropicum, C. pannorum, C. state Arthroderma curreyi, C. state of A. multifidum, and C. state of A. tuberculatum), the authors have realized two series of experimental infestations. Inoculation of these fungi on the back of guinea pigs produced rare erythematous scaling lesions which spontaneously disappeared 3-5 weeks later. No real hair invasion was observed. In white mice, eight weeks after intraperitoneal inoculation, granulomas with necrotic center were observed in the peritoneal tissue with C. keratinophilum, C. tropicum, C. state of A. curreyi and C. state A. tuberculatum. Conidia were often intact in necrotic centers and retrocultures were positive. With C. state of A. curreyi, spherical spores associated with rare budding cells were noted. The pathogenic role of these keratinophilic fungi is uncertain. However, their ability to remain viable for several weeks in skin and peritoneal tissue indicates that they could become pathogen in certain circumstances.

[Different behavior of 22 strains of Emmonsia Cifferi and Montemartini 1959, a monilial fungus, in the lungs of laboratory mice in comparison with their parasitic morphology in vitro]

The 22 strains of Emmonsia Ciferri & Montemartini 1959, inoculated intranasally to laboratory mice are not equally virulent. One month after the inoculation, 15 of the strains had produced adiaspores 120 t9 190 micrometer in diameter in the lung. Another strain produced adiaspores measuring 44 micrometer and 2 others measuring 20 micrometer or 10 micrometer. The remaining 4 strains did not develop in the lung tissue. Four thermophilic strains, which in vitro have adiaspores measuring 8 to 15 micrometer, had adiaspores reaching 120-180 micrometer in vivo. Neither budding nor endosporulation could be observed in any adiaspore.

Mutants of Emmonsia crescens--their pathogenicity and size of adiaspores in vivo

The pathogenicity of seven morphological mutants of Emmonsia crescens was tested by means of intraperitoneal inoculation in mice. All mutants caused adiaspiromycosis. Adiaspores were isolated from granulomas after 2 months and their diameters were determined. Adiaspores from granulomas caused by five mutants (M-5, M-6, M-8, M-9 and M-16) were significantly smaller than adiaspores from granulomas caused by the wild strain, from which the mutants were derived. Two mutants (M-6 and M-9) produced adiaspores of the smallest diameter (130.5 and 119.9 mum) with the lowest variance of values, differing thus most from the original wild strain with adiaspores of 230.4 mum in diameter. A positive correlation was found between the size of the adiaspore in vivo and growth rate of the mycelial stage of Emmonsia crescens in vitro. The mutation characterized by the decreased growth rate of the mycelial stage is phenotypically manifested in the adiasporic stage of the life cycle of Emmonsia crescens, i.e. by the smaller average size of adiaspores in granulomas.

[Comparative sensitivity of several laboratory animals to infection by nasal instillation of the saprophytic phase of Emmonsia crescens Emmons & Jellison, 1960: frequency and intensity of parasitism, histological reactions]

Comparative observations were made on the development of Emmonsia crescens in the lungs of laboratory rats and mice, golden hamsters and guinea pigs after a nasal instillation of a heavy suspension of the saprophytic phase of the fungus. 95% of 80 experimental rats were found to be parasited against 80% of 200 inoculated mice, while only 30% of 70 hamsters and all of 4 guinea pigs showed an infection. The lungs of the mice, rats and guinea pigs were frequently more heavily infected than those of the hamsters. In addition, the adiaspores obtained from the mice and rats had, on average, a diameter double those from the hamsters and their walls were thicker. Thus, the laboratory mice and rats were shown to be better hosts of E. crescens than were golden hamsters.