Developing collaborative works for faster progress on fungal respiratory infections in cystic fibrosis.

Cystic fibrosis (CF) is the major genetic inherited disease in Caucasian populations. The respiratory tract of CF patients displays a sticky viscous mucus, which allows for the entrapment of airborne bacteria and fungal spores and provides a suitable environment for growth of microorganisms, including numerous yeast and filamentous fungal species. As a consequence, respiratory infections are the major cause of morbidity and mortality in this clinical context. Although bacteria remain the most common agents of these infections, fungal respiratory infections have emerged as an important cause of disease. Therefore, the International Society for Human and Animal Mycology (ISHAM) has launched a working group on Fungal respiratory infections in Cystic Fibrosis (Fri-CF) in October 2006, which was subsequently approved by the European Confederation of Medical Mycology (ECMM). Meetings of this working group, comprising both clinicians and mycologists involved in the follow-up of CF patients, as well as basic scientists interested in the fungal species involved, provided the opportunity to initiate collaborative works aimed to improve our knowledge on these infections to assist clinicians in patient management. The current review highlights the outcomes of some of these collaborative works in clinical surveillance, pathogenesis and treatment, giving special emphasis to standardization of culture procedures, improvement of species identification methods including the development of nonculture-based diagnostic methods, microbiome studies and identification of new biological markers, and the description of genotyping studies aiming to differentiate transient carriage and chronic colonization of the airways. The review also reports on the breakthrough in sequencing the genomes of the main Scedosporium species as basis for a better understanding of the pathogenic mechanisms of these fungi, and discusses treatment options of infections caused by multidrug resistant microorganisms, such as Scedosporium and Lomentospora species and members of the Rasamsonia argillacea species complex.

The dermatophyte species Arthroderma benhamiae: intraspecies variability and mating behaviour.

Arthroderma benhamiae is a zoophilic dermatophyte belonging to the Trichophyton mentagrophytes species complex. Here, a population of A. benhamiae wild strains from the same geographical area (Switzerland) was studied by comparing their morphology, assessing their molecular variability using internal transcribed spacer (ITS) and 28S rRNA gene sequencing, and evaluating their interfertility. Sequencing of the ITS region and of part of the 28S rRNA gene revealed the existence of two infraspecific groups with markedly different colony phenotypes: white (group I) and yellow (group II), respectively. For all strains, the results of mating type identification by PCR, using HMG (high-mobility group) and α-box genes in the mating type locus as targets, were in total accordance with the results of mating type identification by strain confrontation experiments. White-phenotype strains were of mating type + (mt+) or mating type - (mt-), whilst yellow-phenotype strains were all mt-. White and yellow strains were found to produce fertile cleistothecia after mating with A. benhamiae reference tester strains, which belonged to a third group intermediate between groups I and II. However, no interfertility was observed between yellow strains and white strains of mt+. A significant result was that white strains of mt- were able to mate and produce fertile cleistothecia with the white A. benhamiae strain CBS 112371 (mt+), the genome of which has recently been sequenced and annotated. This finding should offer new tools for investigating the biology and genetics of dermatophytes using wild-type strains.

Molecular typing and antifungal susceptibility of Exophiala isolates from patients with cystic fibrosis.

The black yeast Exophiala dermatitidis is a frequent agent of colonization of the lungs of patients with cystic fibrosis (CF). A total of 71 clinical isolates of Exophiala from 13 patients were identified at the species level by sequencing the internal transcribed spacer (ITS) regions 1 and 2 of the rDNA genes and typed by random amplification of polymorphic DNA (RAPD), using two different primers, BG-2 and ERIC-1. In vitro susceptibility of these isolates to some systemic antifungal drugs was investigated using the CLSI method. Almost all the isolates were identified as E. dermatitidis, but long-term colonization with the closely related species E. phaeomuriformis was observed in one patient. No clustering was found according to the geographical origin of the isolates, the isolation date or the antifungal susceptibility. Variations were seen in the susceptibility of studied isolates to antifungals but most of them exhibited low susceptibility to amphotericin B and although some patients were successively colonized by two distinct genotypes, most of the isolates were distributed in patient-specific clusters. This phenomenon may be due to genomic variations of E. dermatitidis in the lung environment of CF patients. These results are typical of colonization of the airways of patients by a poorly distributed environmental fungus, which occupies particular reservoirs that need to be defined.

Characterization of new Alternaria alternata--specific rat monoclonal antibodies.

In this study, three different rat hybridoma cell lines secreting monoclonal antibodies (mAbs) recognizing the spores from Alternaria alternata, a plant pathogenic fungus, contaminant of food products and important cause of both allergic rhinitis and asthma, have been characterized. These three mAbs are all of IgM isotype. Two antibodies, A1 and F10, were cross-reactive antibodies recognizing spores from Alternaria, Cladosporium, Penicillium, Aspergillus and Stachybotrys genera, but not the yeasts Saccharomyces cerevisiae or Candida albicans. Competitive and sandwich assays demonstrated that these two mAbs were directed against the same or very close repetitive(s) epitope(s). A1-based sandwich ELISA efficiently detected this epitope in various mould (but not yeast)-soluble extracts prepared from strains grown in the laboratory. Moreover, this A1-based sandwich ELISA detected its cognate epitope in air and dust samples obtained from dwellings. The third antibody, E5, recognized only the spores of Alternaria and the phylogenetically very close Ulocladium botrytis. This E5 antibody is directed against a repetitive epitope found in Alternaria and Ulocladium laboratory extracts and can be used in a sandwich assay for the quantification of these moulds. Therefore, E5 antibody is a promising tool for the development of Alternaria-Ulocladium-specific immunoassays, while A1 and F10 could be interesting tools for the quantification of the total mould biomass.

Microsporum mirabile and its teleomorph Arthroderma mirabile, a new dermatophyte species in the M. cookei clade.

A novel dermatophyte species is described in the Microsporum cookei clade. It differs significantly from known taxa in the two molecular markers analyzed, i.e., ITS and partial ß-tubulin (BT2). Morphologically the species was characterized by smooth- or only slightly rough-walled conidia, but isolates rapidly became pleomorphic with sparse, smooth- and thick-walled macroconidia in addition to microconidia. A teleomorph was found after mating.

Case report: Infrapatellar bursitis caused by Prototheca wickerhamii.

A 54-year-old immunocompetent man presented with an infrapatellar bursitis caused by Prototheca wickerhamii. Because of clinical and microbiological relapse two weeks after bursectomy, six weekly injections of 5 mg of conventional amphotericin B were chosen for intrabursal treatment. Four months after completion of the treatment, the patient remains cured.

Comparative proteomic profiles of Aspergillus fumigatus and Aspergillus lentulus strains by surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS).

BACKGROUND: Surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS) was applied to analyze the protein profiles in both somatic and metabolic extracts of Aspergillus species. The study was carried out on some Aspergillus species within the Fumigati section (Aspergillus fumigatus wild-types and natural abnormally pigmented mutants, and Aspergillus lentulus). The aim was to validate whether mass spectrometry protein profiles can be used as specific signatures to discriminate different Aspergillus species or even mutants within the same species. RESULTS: The growth conditions and the SELDI-TOF parameters were determined to generate characteristic protein profiles of somatic and metabolic extracts of Aspergillus fumigatus strains using five different ProteinChips®, eight growth conditions combining two temperatures, two media and two oxygenation conditions. Nine strains were investigated: three wild-types and four natural abnormally pigmented mutant strains of A. fumigatus and two strains of A. lentulus. A total of 242 fungal extracts were prepared. The spectra obtained are protein signatures linked to the physiological states of fungal strains depending on culture conditions. The best resolutions were obtained using the chromatographic surfaces CM10, NP20 and H50 with fractions of fungi grown on modified Sabouraud medium at 37 °C in static condition. Under these conditions, the SELDI-TOF analysis allowed A. fumigatus and A. lentulus strains to be grouped into distinct clusters. CONCLUSIONS: SELDI-TOF analysis distinguishes A. fumigatus from A. lentulus strains and moreover, permits separate clusters of natural abnormally pigmented A. fumigatus strains to be obtained. In addition, this methodology allowed us to point out fungal components specifically produced by a wild-type strain or natural mutants. It offers attractive potential for further studies of the Aspergillus biology or pathogenesis.

Molecular analysis and mating behaviour of the Trichophyton mentagrophytes species complex.

Isolates of the Trichophyton mentagrophytes complex vary phenotypically. Whether the closely related zoophilic and anthropophilic anamorphs currently associated with Arthroderma vanbreuseghemii have to be considered as members of the same biological species remains an open question. In order to better delineate species in the T. mentagrophytes complex, we performed a mating analysis of freshly collected isolates from humans and animals with A. benhamiae and A. vanbreuseghemii reference strains, in comparison to internal transcribed spacer (ITS) and 28S rDNA sequencing. Mating experiments as well as ITS and 28S sequencing unambiguously allowed the distinction of A. benhamiae and A. vanbreuseghemii. We have also shown that all the isolates from tinea pedis and tinea unguium identified as T. interdigitale based on ITS sequences mated with A. vanbreuseghemii tester strains, but had lost their ability to give fertile cleistothecia. Therefore, T. interdigitale has to be considered as a humanized species derived from the sexual relative A. vanbreuseghemii.

Unusual Aspergillus species in patients with cystic fibrosis.

Poorly sporulating Aspergillus isolates from patients with cystic fibrosis (CF) are generally identified in routine procedures as Aspergillus spp. In this study, we identified and characterized 11 isolates belonging to two unusual Aspergillus species of the section Fumigati (A. lentulus and Neosartorya pseudofischeri) recovered from four different patients. Aspergillus lentulus was found occasionally during a 10-year follow-up study of one CF patient colonized by A. fumigatus. Neosartorya pseudofischeri was isolated from three patients followed in different European hospitals. This species was recovered from two sputum samples of one patient, and from four successive samples of the two other patients, suggesting that it may be responsible for chronic colonization. Both species were isolated together with A. fumigatus. Isolates from both species did not grow at 50°C, and DNA sequence analysis, together with further morphological observations permitted identification at the species level. Growth at different temperatures and antifungal susceptibility were also investigated. All the isolates of N. pseudofischeri exhibited a very low susceptibility to voriconazole (VRZ) whereas a very low susceptibility to VRZ and amphotericin B was seen with the A. lentulus isolates.

Exophiala (Wangiella) dermatitidis and cystic fibrosis - Prevalence and risk factors.

The objective of this prospective study was to assess the prevalence of Exophiala dermatitidis in respiratory secretions of patients with cystic fibrosis (CF) and to identify risk factors for its presence. The results of all cultures performed over a 2-year period in non lung-transplant patients in our CF clinic were included in the study. Samples consisted of sputum (whenever possible) or deep pharyngeal aspirate after a session of physiotherapy. Specimens were inoculated onto Sabouraud gentamicin-chloramphenicol agar (SGCA) medium (Becton-Dickinson) and incubated at 35°C for 2 days and then at ambient temperature (15-25°C) for 3 weeks. The whole study group included 154 patients (mean age ± SD: 18.5 y ± 11.69). E. dermatitidis was isolated from 58 specimens (2.8%) of nine patients (5.8%) out of total of 2065 cultures prepared during the study period. All E. dermatitidis culture-positive patients were pancreatic insufficient and ≥12 y of age. Almost all (8/9) were homozygous for the F508 del mutation. Aspergillus fumigatus colonization and genotype seemed to be predisposing factors. No other significant characteristic was identified in this group, either in terms of predominant bacterial pathogen or treatment. A distinct comparative study performed over 3 months in our laboratory revealed that the use of SGCA yielded identical isolation rates of E. dermatitidis as erythritol-chloramphenicol agar (ECA).

Fungalysin and dipeptidyl-peptidase gene transcription in Microsporum canis strains isolated from symptomatic and asymptomatic cats.

Microsporum canis is the main pathogenic fungus that causes a superficial cutaneous infection called dermatophytosis in domestic carnivores. In cats, M. canis causes symptomatic or asymptomatic infection. Recent conflicting data raise the question of whether the clinical status of the infected cat (symptomatic or asymptomatic) is directly correlated to the proteolytic activity of M. canis strains. Here, the transcription of fungalysin and dipeptidyl-peptidase genes (DPP) of M. canis was compared between four strains isolated from symptomatic and asymptomatic cats during the first steps of the infection process, namely in arthroconidia, during adherence of arthroconidia to corneocytes and during early invasion of the epidermis, using a new ex vivo model made of feline epidermis. There was no detectable transcription of the fungalysin genes in arthroconidia or during the first steps of the infection process for any of the tested strains, suggesting that these proteases play a role later in the infection process. Among DPP, the DPP IV gene was the most frequently transcribed both in arthroconidia and later during infection (adherence and invasion), but no significant differences were observed between M. canis strains isolated from symptomatic and asymptomatic cats. This study shows that the clinical aspect of M. canis feline dermatophytosis depends upon factors relating to the host rather than to the proteolytic activity of the infective fungal strain.

Melanin is an essential component for the integrity of the cell wall of Aspergillus fumigatus conidia.

BACKGROUND: Aspergillus fumigatus is the most common agent of invasive aspergillosis, a feared complication in severely immunocompromised patients. Despite the recent commercialisation of new antifungal drugs, the prognosis for this infection remains uncertain. Thus, there is a real need to discover new targets for therapy. Particular attention has been paid to the biochemical composition and organisation of the fungal cell wall, because it mediates the host-fungus interplay. Conidia, which are responsible for infections, have melanin as one of the cell wall components. Melanin has been established as an important virulence factor, protecting the fungus against the host's immune defences. We suggested that it might also have an indirect role in virulence, because it is required for correct assembly of the cell wall layers of the conidia. RESULTS: We used three A. fumigatus isolates which grew as white or brown powdery colonies, to demonstrate the role of melanin. Firstly, sequencing the genes responsible for biosynthesis of melanin (ALB1, AYG1, ARP1, ARP2, ABR1 and ABR2) showed point mutations (missense mutation, deletion or insertion) in the ALB1 gene for pigmentless isolates or in ARP2 for the brownish isolate. The isolates were then shown by scanning electron microscopy to produce numerous, typical conidial heads, except that the conidia were smooth-walled, as previously observed for laboratory mutants with mutations in the PKSP/ALB1 gene. Flow cytometry showed an increase in the fibronectin binding capacity of conidia from mutant isolates, together with a marked decrease in the binding of laminin to the conidial surface. A marked decrease in the electronegative charge of the conidia and cell surface hydrophobicity was also seen by microelectrophoresis and two-phase partitioning, respectively. Ultrastructural studies of mutant isolates detected considerable changes in the organisation of the conidial wall, with the loss of the outermost electron dense layer responsible for the ornamentations seen on the conidial surface in wild-type strains. Finally, analysis of the conidial surface of mutant isolates by atomic force microscopy demonstrated the absence of the outer cell wall rodlet layer which is composed of hydrophobins. CONCLUSION: These results suggest that, in addition to a protective role against the host's immune defences, melanin is also a structural component of the conidial wall that is required for correct assembly of the cell wall layers and the expression at the conidial surface of adhesins and other virulence factors.

Defense by volatiles in leaf-mining insect larvae.

The defense strategy of an insect toward natural enemies can include a trait that appears at first sight to contradict its defensive function. We explored phylogeny, chemistry, and defense efficiency of a peculiar group of hymenopteran sawfly larvae where this contradiction is obvious. Pseudodineurini larvae live in leaf mines that protect them from some enemies. Disturbed larvae also emit a clearly perceptible lemon-like odor produced by ventral glands, although the mine hampers the evaporation of the secretion. The mine could also lead to autointoxication of a larva by its own emitted volatiles. Citral was the major component in all Pseudodineurini species, and it efficiently repels ants. We conclude that full-grown larvae that leave their mine to pupate in the soil benefit from citral by avoiding attacks from ground-dwelling arthropods such as ants. In some species, we also detected biosynthetically related compounds, two 8-oxocitral diastereomers (i.e., (2E,6E)- and (2E,6Z)-2,6-dimethylocta-2,6-dienedial). Synthetic 8-oxocitral proved to be a potent fungicide, but not an ant repellent. The discrete distribution of 8-oxocitral was unrelated to species grouping in the phylogenetic tree. In contrast, we discovered that its presence was associated with species from humid and cold zones but absent in species favoring warm and dry environments. The former should be protected by 8-oxocitral when faced with a fungal infestation while crawling into the soil. Our work shows the importance of integrating knowledge about behavior, morphology, and life history stages for understanding the complex evolution of insects and especially their defense strategies.

Occurrence and relevance of filamentous fungi in respiratory secretions of patients with cystic fibrosis--a review.

The colonization of airways by filamentous fungi and the development of respiratory infections require some predisposing factors as encountered in patients with cystic fibrosis (CF). Indeed, the defective mucociliary clearance which characterizes the disease is associated with local immunological disorders. In addition, the prolonged therapy with antibiotics and the use of corticosteroid treatments also facilitate fungal growth. An important fungal biota has been described in respiratory secretions of patients suffering from CF. Aspergillus fumigatus, Scedosporium apiospermum and Aspergillus terreus for filamentous fungi and Candida albicans for yeasts are the main fungal species associated with CF. Although less common, several fungal species including Aspergillus flavus and Aspergillus nidulans may be isolated transiently from CF respiratory secretions, while others such as Exophiala dermatitidis and Scedosporium prolificans may chronically colonize the airways. Moreover, some of them like Penicillium emersonii and Acrophialophora fusispora are encountered in humans almost exclusively in the context of CF. As fungal complications in CF patients are essentially caused by filamentous fungi the present review will not include works related to yeasts. In CF patients, fungi may sometimes be responsible for deterioration of lung function, as occurs in allergic broncho-pulmonary aspergillosis (ABPA) which is the most common fungal disease in this context. Additionally, although the clinical relevance of the fungal airway colonization is still a matter of debate, filamentous fungi may contribute to the local inflammatory response, and therefore to the progressive deterioration of the lung function.

Microsatellite typing of Aspergillus fumigatus isolates recovered from deep organ samples of patients with invasive aspergillosis.

Microsatellite typing was used to analyze 41 Aspergillus fumigatus isolates from 9 patients with proven invasive aspergillosis hospitalized in 2 different centers. No strains were shared between patients. For 8 of 9 patients, a single genotype was found for the isolates recovered from all anatomic sites involved.

Manganese superoxide dismutase based phylogeny of pathogenic fungi.

Superoxide dismutases (SODs), which provide protection against oxidative stress, exhibit an essential role for fungal cell survival, especially during host invasion. Here, 20 partial SOD sequences from 19 pathogenic fungi were determined and aligned with 43 homologous fungal sequences from databases. All sequences encoded tetrameric manganese (Mn)-containing SODs showing predicted cytosolic or mitochondrial subcellular localization. Numerous fungi possessed both cytosolic and mitochondrial MnSODs in addition to the mainly cytosolic copper/zinc isozyme. Moreover, MnSOD sequence variability was higher than SSU rRNA and similar to ITS rRNA, suggesting MnSOD could be used to identify closely related fungal species. MnSOD- and SSU rRNA-based phylogenetic trees were constructed and compared. Despite a more complex topology of the MnSOD tree, due to several gene duplication events, all the classic fungal classes and orders were recovered. A salient point was the existence of two paralogous cytosolic and mitochondrial MnSODs in some Ascomycota. A hypothetical evolutionary scenario with an early gene duplication of the "mitochondrial" gene is proposed.

Disseminated Scedosporium apiospermum infection in a cystic fibrosis patient after double-lung transplantation.

Scedosporium apiospermum is a saprophytic ubiquitous filamentous fungus. It can cause a wide spectrum of diseases, from localized to invasive infections. S apiospermum has been described as one of the major fungal agents of chronic colonization of airways in cystic fibrosis (CF) patients. Invasive infections due to S apiospermum are only rarely reported in CF after lung transplantation. A 26-year-old woman with CF and chronic bronchial colonization by S apiospermum developed bilateral chorioretinitis and subcutaneous nodules 4 weeks after double-lung transplantation (LTx). Isolates of S apiospermum from sputum samples before and after LTx and from vitreal fluid were typed by random amplification of polymorphic DNA (RAPD). The patient was treated with voriconazole (VRC). The patient improved with VRC given orally for 6 months. Two days after VRC discontinuation, she developed sub-acute meningitis (isolation of S apiospermum from the cerebrospinal fluid). She was again given VRC, but died 23 days later from uncontrolled fungal infection. Molecular typing of clinical isolates of S apiospermum performed by RAPD demonstrated that all isolates belonged to the same genotype. S apiospermum is a frequent, but late colonizing fungal agent in CF patients. In the case of LTx, these patients can develop invasive infection due to the colonizing strain, as confirmed by molecular typing.

Susceptibility testing of sequential isolates of Aspergillus fumigatus recovered from treated patients.

Two-hundred sequential Aspergillus fumigatus isolates recovered from 26 immunocompromised patients with invasive aspergillosis or bronchial colonization were tested for their in vitro susceptibility to posaconazole, itraconazole, voriconazole, terbinafine and amphotericin B. Twenty-one patients were treated with amphotericin B and/or itraconazole. Antifungal susceptibilities of the isolates recovered before treatment were not significantly different from those of isolates recovered after the onset of antifungal therapy. The highest MICs were 0.125, 0.5, 0.5, 1 and 1 microg ml(-1) for posaconazole, itraconazole, voriconazole, terbinafine and amphotericin B, respectively. It is concluded that the emergence of resistance in A. fumigatus during antifungal therapy with amphotericin B or itraconazole is an uncommon phenomenon.