We report on a case of phaeohyphomycosis caused by Alternaria infectoria in a renal transplant recipient with pulmonary infiltrates and multiple skin lesions. Diagnosis was based on microscopy and culture of the skin lesions. Treatment consisted of a combination of surgical excision and systemic antifungal therapy, first with itraconazole and subsequently with liposomal amphotericin B, for 39 days. At a 20-month follow-up visit, no recurrence of the skin lesions or the pulmonary infiltrates had occurred.
Dermatophytes are fungi capable of invading keratinized tissues and are responsible for the most common fungal infection worldwide: dermatophytosis. Identification of these organisms to the species level is often necessary for the correct treatment of these infections, and is always recommended from an epidemiological point of view. Since the identification of dermatophytes is sometimes problematic, we assessed whether Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) could provide a useful tool to identify dermatophytes of the Trichophyton mentagrophytes complex. A reference database was constructed with 17 strains of six different species belonging to this complex. A total of 54 dermatophyte strains of the Belgian co-ordinated collections of micro-organisms, Scientific Institute of Public Health, Brussels, Belgium (BCCM™/IHEM) collection were used to challenge this database; 89% of the tested strains (not used as reference strains in the database) could readily be identified. When incorrect identifications were encountered, the confusion was always between phylogenetically closely related taxa which indicates that observations made by MALDI-TOF MS correlate with phylogenetic data. To assess this observation, a dendrogram outlining the similarities between the obtained spectra was constructed. Strikingly, the relationships found in this dendrogram were highly similar to the ones observed in the phylogenetic tree recently reported by Beguin and co-workers. In conclusion, MALDI-TOF MS is a fast and reliable tool for the identification of dermatophytes, since it can even discriminate between the closely related species of the T. mentagrophytes complex. Moreover, our data indicate that the data obtained by MALDI-TOF MS correlate with phylogenetic data.
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.
Trichophyton quinckeanum, known as the causative agent of mouse favus, has been a subject of controversy since its discovery, 125 years ago. The purpose of this study was to examine the phylogenetic relationships between this fungus and related taxa. To achieve this objective, the ITS rDNA region, as well as actin and β-tubulin gene regions of various isolates were sequenced. Bayesian inference and maximum likelihood analyses were conducted with T. rubrum as outgroup. Our study showed that strains identified as T. quinckeanum and others identified as T. schoenleinii are part of the complex T. mentagrophytes, and that their genotype cannot be confused with any other dermatophytes. Furthermore, this study demonstrates that the choice of the neotype of T. mentagrophytes was inappropriate. The beta-tubulin topology also revealed that isolates of T. interdigitale form a genetically distinct population from the type strains of Arthroderma vanbreuseghemii. Therefore, contrary to what is generally accepted, the anthropophilic species T. interdigitale cannot be considered as the anamorph associated with the latter.
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