The spectrum of opportunistic filamentous fungi present in the CBS culture collection

The mould collection of the Centraalbureau voor Schimmelcultures, Baarn, The Netherlands, was screened for isolates originating from warm-blooded animals. The range of species indicates that distribution of clinically relevant, pathogenic or opportunistic strains over the fungal kingdom is non-random. Some opportunistic fungi possess adaptations to life under hostile environmental conditions, enabling them to survive inside the human body. Presence of melanin or carotene seems to be an important virulence factor. Opportunistic fungi which sporulate in submersion are able to disseminate or cause severe local mycoses when the aspecific immune system of the host is impaired. Mycoses caused by a few dimorphic fungi, mostly in their natural ecological niche living in association with vertebrates, are promoted by specific immune deficiencies.     

Accumulation of gliotoxin, a cytotoxic mycotoxin from Aspergillus fumigatus, in blue mussel (Mytilus edulis).

A strain of Aspergillus fumigatus has been isolated from sediments of a mussel bed. When cultured in hyper saline conditions (with sea-water), it produces a cytotoxic and immunosuppressive toxin, gliotoxin, which is excreted in an exudate. In order to know if this toxin could represent a risk for shellfish consumers, an experiment of bioaccumulation of gliotoxin in mussel has been carried out. After 6 days of contamination, toxin was accumulated in the meat of the mussels, at a level up to 2.9 microg/mg of extract weight, with a mode of contamination different to the classical digestive process described for a majority of marine toxins, but similar to the contamination mode of domoic acid.     

Keratinolytic fungi in sewage sludge applied to devastated urban soil. A preliminary experiment

The qualitative and quantitative (q/q) changes of keratinolytic fungi in soil mixtures with added sewage sludge were examined during a preliminary reclamation experiment. Sludge before land application was characterized by the weak growth of keratinolytic fungi. In devastated urban soil, abundant fungal growth was observed. Over a 19‐month reclamation period, decreasing frequency of Chrysosporium concurrent with the enrichment of the mixture with the geophilic dermatophytes Arthroderma quadrifidum and A. uncinatum were clearly seen. The results are discussed with respect to possible ecological factors influencing the occurrence of keratinolytic fungi in the materials examined. The public health risk associated with the application of sewage sludge for reclamation is also discussed.     

Monoclonal antibodies to fungi of significance to the quality of foods and feeds

Monoclonal antibodies (MAbs) were raised against Penicillium aurantiogriseum var. melanoconidium. Cross‐reactivity studies were carried out against 12 ‘field’ and 27 ‘storage’ fungi. Two MAbs (MAbs 32 and 37) reacted with all of the fungi tested and a third (MAb 38) with 38 out of the 39 fungi (although weakly with some). Monoclonal antibodies 32 and 37, but not MAb 38, were found to react to a degree with ‘clean’ barley. Enzyme‐linked immunosorbent assay (ELISA) using MAb 38 and extracts of barley inoculated with the homologous antigen showed a clear relationship between absorbance and amount of fungal growth. It is suggested that these MAbs could be used in a broad‐spectrum assay to detect fungi of significance to the quality of foods and feeds.     

Autonomously replicating plasmids carrying theAMA1 region inPenicillium chrysogenum

Plasmid vectors containing theAMA1 sequence transformed with high efficiency and replicated autonomously inPenicillium chrysogenum. The efficiency of transformation ofP. chrysogenum was related to the length of theAMA1 fragment used for constructing the different autonomously replicating plasmids. One of the two palindromic inverted repeats ofAMA1 (the 2.2-kbSalI-HindIII fragment) is sufficient to confer autonomous replication and a high transformation efficiency. Deletion of the 0.6-kb central fragment located between the inverted repeats did not affect either the ability of the plasmids to replicate autonomously or the efficiency of transformation, but did alter the mitotic stability and the plasmid copy number. Deletion of any fragment of the 2.2-kb repeat caused the loss of the ability to replicate autonomously and reduced the transformation efficiency. Most of the transformants retained the original plasmid configuration, as multimers and without reorganization, after several rounds of autonomous replication. TheAMA1 region works as an origin of replication inP. chrysogenum andA. nidulans but not apparently inAcremonium chrysogenum.     

The molecular immunology of human susceptibility to fungal diseases: lessons from single gene defects of immunity

Introduction: Fungal diseases are a threat to human health. Therapies targeting the fungus continue to lead to disappointing results. Strategies targeting the host response represent unexplored opportunities for innovative treatments. To do so rationally requires the identification and neat delineation of critical mechanistic pathways that underpin human antifungal immunity. The study of humans with single-gene defects of the immune system, i.e. inborn errors of immunity (IEIs), provides a foundation for these paradigms.

Areas covered: A systematic literature search in PubMed, Scopus, and abstracts of international congresses was performed to review the history of genetic resistance/susceptibility to fungi and identify IEIs associated with fungal diseases. Immunologic mechanisms from relevant IEIs were integrated with current definitions and understandings of mycoses to establish a framework to map out critical immunobiological pathways of human antifungal immunity.

Expert opinion: Specific immune responses non-redundantly govern susceptibility to their corresponding mycoses. Defining these molecular pathways will guide the development of host-directed immunotherapies that precisely target distinct fungal diseases. These findings will pave the way for novel strategies in the treatment of these devastating infections.     

Dustborne and airborne fungal propagules represent a different spectrum of fungi with differing relations to home characteristics

BACKGROUND: Exposure to fungi is often assessed by culturing floor dust or air samples. Our objective was to evaluate the relationships between dustborne and airborne fungi and to identify factors that modify these relationships. METHODS: From November 1994 to September 1996 sequential duplicate 45-l air samples were collected in bedrooms of 496 homes in the Boston area, using a Burkard culture plate sampler. After air sampling, bedroom floors were sampled with a vacuum cleaner that was modified to collect dust in a cellulose extraction thimble. Dust was sieved, and the fine dust was dilution-plated onto DG-18 media. RESULTS: Concentrations of total culturable fungi per gram of bedroom-floor dust were correlated weakly, but significantly, with those of indoor air (r = 0.13, P < 0.05). Concentrations of some individual taxa in the dust and indoor air were also weakly associated. Adjusting for the concentrations of fungi in outdoor air, dustborne fungal concentrations were positively associated with those in indoor air for the taxa Cladosporium and Penicillium, but not for total fungi. The indoor air fungal levels were often predicted by different covariates to those predicting fungal levels in dust. The type of housing (house or apartment) and the presence of carpeting were often predictive factors for dust fungi. In contrast, outdoor fungal levels were often predictive of the indoor air fungal levels. CONCLUSIONS: Because our data do not indicate a strong overall relationship between culturable fungi in dust and indoor air, the results from these two methods (dust and air sampling) likely represent different types of potential fungal exposures to residents. It may be essential to collect both air and dust samples, as well as information on housing characteristics, as indicators for fungal exposure.     

Confirmed Cases of Ophidiomycosis in Museum Specimens from as Early as 1945, United States

Ophidiomycosis represents a conservation threat to wild snake populations. The disease was reported in North America early in the 21st century, but the history of ophidiomycosis has not been investigated. We examined museum specimens and confirmed cases of ophidiomycosis >50 years before the disease’s reported emergence.