Dermatophytoses affect about 25% of the world population, and the filamentous fungus Trichophyton rubrum is the main causative agent of this group of diseases. Dermatomycoses are caused by pathogenic fungi that generally trigger superficial infections and that feed on keratinized substrates such as skin, hair, and nails. However, there are an increasing number of reports describing dermatophytes that invade deep layers such as the dermis and hypodermis and that can cause deep infections in diabetic and immunocompromised patients, as well as in individuals with immunodeficiency. Despite the high incidence and importance of dermatophytes in clinical mycology, the diagnosis of this type of infection is not always accurate. The conventional methods most commonly used for mycological diagnosis are based on the identification of microbiological and biochemical features. However, in view of the limitations of these conventional methods, molecular diagnostic techniques are increasingly being used because of their higher sensitivity, specificity and rapidity and have become more accessible. The most widely used molecular techniques are conventional PCR, quantitative PCR, multiplex PCR, nested, PCR, PCR-RFLP, and PCR-ELISA. Another promising technique for the identification of microorganisms is the analysis of protein profiles by MALDI-TOF MS. Molecular techniques are promising but it is necessary to improve the quality and availability of the information in genomic and proteomic databases in order to streamline the use of bioinformatics in the identification of dermatophytes of clinical interest.

Contamination of preharvest and stored peanuts (Arachis hypogaea L.) by aflatoxigenic strains of Aspergillus flavus is an important economical and food safety problem in many tropical and subtropical areas of the world. The present investigation reports the antifungal activity of a halitoxins/amphitoxins enriched extract obtained from the sponge Amphimedon sp. (HAEEAsp), and of batzelladine L isolated from the sponge Monanchora arbuscula on Aspergillus flavus isolated from stored peanuts. A PCR system directed against the ITS region and aflatoxin biosynthetic pathway genes of A. flavus was applied for identification of aflatoxin producing strains. The HAEEAsp extract and batzelladine L showed minimal inhibitory concentration (MIC) in the range between 1.9 to 15.6 µg/mL and between 1.9 to 7.8 µg/mL, respectively. The minimal fungicide concentration (MFC) of HAEEAsp extract and batzelladine L was in the range between 3.9 to 31.3 µg/mL and 3.9 to 15.6 µg/mL, respectively. These results indicate that these marine alkaloids may be further explored for the development of potential lead compounds active against aflatoxigenic fungi.

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Background: Trichophyton rubrum is the most common aetiological agent of human dermatophytoses. These infections mainly occur in keratinised layers such as skin, hair and nails because the fungus uses keratin as a nutrient source. Fluconazole and amphotericin are antifungal agents most commonly used to treat dermatophytoses and acts on cell membrane ergosterol. Despite the clinical importance of T rubrum, the mechanisms underlying the fungal-host relationship have not yet been clarified. Tandem repeats (TRs) are short DNA sequences that are involved in a variety of adaptive functions, including the process of fungal infection. It is known that the larger the number of TRs in the genome, the greater the capacity of cell-cell junction and surface adhesion, especially when these repeats are present in regions encoding cell surface proteins. Objectives: To identify in silico T rubrum genes containing TR patterns and to analyse the modulation of these genes in culture medium containing keratin (a model simulating skin infection) and antifungal drugs. Methods: The Dermatophyte Tandem Repeats Database (DTRDB) and the FaaPred tool were used to identify four T rubrum genes containing TR patterns. Quantitative real-time (RT) PCR was used to evaluate the gene expression during the growth of T rubrum on keratin and in the presence of fluconazole, amphotericin B and Congo red (acts in the cell wall).Results: The expression of these genes was found to be induced in culture medium containing keratin. In addition, these genes were induced in the presence of antifungal agents, especially fluconazole, indicating an adaptive response to the stress caused by this drug. Conclusion:The results suggest an important role of genes containing TRs in the fungal-host interaction and in the susceptibility to inhibitory compounds, indicating these sequences as new potential targets for the development of antifungal agents. K E Y W O R D S adhesin, cell wall proteins, fluconazole, fungal infection, gene expression | 611 de ABReU et Al.

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