Tinea capitis Dermatophytes: Susceptibility to Antifungal Drugs Tested in vitro and in vivo

Mock, M.; Monod, M.; Baudraz‐Rosselet, F.; Panizzon, Renato G.

doi:10.1159/000018032

Cited by 66 publications

(60 citation statements)

References 14 publications

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“…In terms of molecular approach, genotyping of dermatophyte strains has a number of potential epidemiological and clinical applications. As fungal species causing dermatophytosis can only be identified in 2-3 weeks after a positive culture, a rapid PCR method should be helpful in defining prevention and therapeutic strategies (Fernandez-Torres et al, 2003;Kardjeva et al, 2006;Mock et al, 1998). The T. mentagrophytes MnSOD and ITS genes were targeted in order to improve the laboratory identification of dermatophytes.…”

Section: Discussionmentioning

confidence: 99%

Phylogenetic analysis of Trichophyton mentagrophytes human and animal isolates based on MnSOD and ITS sequence comparison

et al. 2007

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Dermatophytes are keratinophilic fungi able to infect keratinized tissues of human or animal origin. Among them, Trichophyton mentagrophytes is known to be a species complex composed of several species or variants, which occur in both human and animals. Since the T. mentagrophytes complex includes both anthropophilic and zoophilic pathogens, accurate molecular identification is a critical issue for comprehensive understanding of the clinical and epidemiological implications of the genetic heterogeneity of this complex. Here, 41 T. mentagrophytes isolates from either human patients (14 isolates) or animals (27 isolates) with dermatophytosis were prospectively isolated by culture and identified on morphological bases at the University Hospital Centres of Lille and Poitiers, and the Veterinary School of Alfort, respectively. The isolates were differentiated by DNA sequencing of the variable internal transcribed spacer (ITS) regions flanking the 5.8S rDNA, and of the housekeeping gene encoding the manganese-containing superoxide dismutase (MnSOD), an enzyme which is involved in defence against oxidative stress and has previously provided interesting insight into both fungal taxonomy and phylogeny. ITS1-ITS2 regions and MnSOD sequences successfully differentiate between members of the T. mentagrophytes complex and the related species Trichophyton rubrum. Whatever the phylogenetic marker used, members of this complex were classified into two major clades exhibiting a similar topology, with a higher variability when the ITS marker was used. Relationships between ITS/MnSOD sequences and host origin, clinical pattern and phenotypic characteristics (macroscopic and microscopic morphologies) were analysed.

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Section: Discussionmentioning

confidence: 99%

Phylogenetic analysis of Trichophyton mentagrophytes human and animal isolates based on MnSOD and ITS sequence comparison

et al. 2007

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“…Here, we have used two inocula measured spectrophotometrically, which allowed us to obtain suspensions with no particularly significant dispersion in the number of particles. (3,15,24), but their results have showed great variability. This is likely due to the lack of standardization of different parameters that can influence MICs determination, such as inoculum (14), length and temperature of incubation (7,20,21), and endpoint criteria (9).…”

Section: Discussionmentioning

confidence: 99%

Collaborative Evaluation of Optimal Antifungal Susceptibility Testing Conditions for Dermatophytes

et al. 2002

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A multicenter study was conducted to define the most suitable testing conditions for antifungal susceptibility of dermatophytes. Broth microdilution MICs of clotrimazole, itraconazole, and terbinafine were determined in three centers against 60 strains of dermatophytes. The effects of inoculum density (ca. 10 3 and 10 4 CFU/ml), incubation time (3, 7, and 14 days), endpoint criteria for MIC determination (complete [MIC-0] and prominent [MIC-2] growth inhibition), and incubation temperature (28 and 37°C) on intra-and interlaboratory agreement were analyzed. The optimal testing conditions identified were an inoculum of 10 4 CFU/ml, a temperature of incubation of 28°C, an incubation period of 7 days, and MIC-0.Dermatophytes are a group of morphologically and physiologically related molds that cause well-defined infections in vertebrates. The incidence of dermatophytoses has increased over recent years, particularly in immunocompromised patients (29,30,32,33). The choice of the proper treatment is determined by the site and extent of the infection and the species involved, as well as by the efficacy, safety profile, and kinetics of the available drugs. For localized nonextensive lesions, topical therapies with clotrimazole (CLT) are generally used. For tinea unguium, scalp ringworm, extensive infections, or skin lesions with folliculitis, systemic antifungal treatment is necessary (1,4,23,26). Oral drugs such as itraconazole (ITC) and terbinafine (TRB) are the antifungal agents currently most used to treat severe infections (4, 23). Some novel compounds, such as UR-9825, posaconazole, voriconazole, or ravuconazole, also appear to be promising candidates for the treatment of dermatophytosis (2,10,28).In the in vitro method proposed by the National Committee for Clinical Laboratory Standards (NCCLS) for testing molds (25), the dermatophytes were not included. Therefore, it is necessary to develop a reproducible standardized method for these important fungi that would lead to protocols for proper treatment. In recent years, some authors, possibly encouraged by the development of the above-mentioned reference method, have published various articles wherein several species of dermatophytes have been tested (11,27,28,34). In these works, different adaptations or modifications of the NCCLS methods have been assayed, although other techniques have also been used (3,12,15). The results obtained have been clearly contradictory in some aspects, which makes evident the need for standardization and the development of reference methods. Recently, we evaluated the activity of 11 antifungal drugs against an important number of strains of dermatophytes (n ϭ 508) by using a microdilution method (10). In that study the testing conditions adopted were an inoculum size of 10 4 CFU/ml, a temperature and time of incubation of 28°C and 7 days, respectively, and the MIC endpoint determination was 50% growth inhibition for azoles and 100% for the rest. It is unknown whether varying the conditions would have changed the results significantly....

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“…The cultures were incubated at 30°C. Dermatophytes were identified after 14 to 21 days following macroscopic and microscopic examinations (9,10,15). When necessary, the determination of Microsporum canis was confirmed after inoculation on lactritmel agar, where the fungus produces a large amount of characteristic, spindle-shaped macroconidia (10).…”

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confidence: 99%

“…At present, in clinical laboratories, a fungal species causing an infection can only be identified after growing in culture for 2 to 3 weeks. Rapid identification by PCR is particularly helpful in cases of tinea capitis, where the knowledge of the exact species of dermatophyte in clinical samples is needed before prescribing the appropriate treatment (10). The sequence of an unknown fungus isolated from dermatological samples can now be routinely compared with rDNA sequences from the EMBL GenBank database.…”

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confidence: 99%

Identification of Dermatophyte Species by 28S Ribosomal DNA Sequencing with a Commercial Kit

et al. 2003

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We have shown that dermatophyte species can be easily identified on the basis of a DNA sequence encoding a part of the large-subunit (LSU) rRNA (28S rRNA) by using the MicroSeq D2 LSU rRNA Fungal Sequencing Kit. Two taxa causing distinct dermatophytoses were clearly distinguished among isolates of the Trichophyton mentagrophytes species complex.Dermatophytes are the main cause of superficial mycoses (9,15,16). These fungi have the capacity to invade keratinized tissue of humans or animals to produce infections that are generally restricted to the corneocytes of the skin, hair, and nails. Among the approximately 10 species isolated in Europe, Trichophyton rubrum and T. mentagrophytes are the most commonly observed, with frequencies varying from 27 to 74% and from 17 to 41%, respectively (13).Dermatophytes are usually identified on the basis of macroscopic appearance, together with microscopic examination of cultures. Important characteristics are the rate of growth, the shape and texture of the culture on solid media, color, diffusion of pigments into agar, and sporulation. However, identification of dermatophytes often remains difficult or uncertain because there are variations from one isolate to another. Recent advances in molecular biology and progress in technology have allowed the development of new techniques for species determination and strain typing in microbiology. The molecular approach used to identify fungi is often based on sequence analysis of the ribosomal DNA (rDNA) and in particular on the internal transcribed spacer (ITS). The polymorphism of the ITS1 and ITS2 regions flanking the DNA sequence encoding the 5.8S rRNA was previously shown to be suitable for the identification of clinically important yeasts (1), Aspergillus sp. (8),and dermatophyte species (3-5). In contrast, the gene coding for the small-subunit rRNA (18S rRNA) did not discriminate sufficiently between dermatophyte species (7).The MicroSeq D2 large-subunit (LSU) rRNA Fungal Sequencing Kit (Applied Biosystems, Rotkreuz, Switzerland) was recently developed to identify fungal species after amplification of a partial sequence of the DNA encoding the LSU rRNA (28S rDNA). The sequence of a given fungus can then be compared for identification with the rDNA sequences of the MicroSeq D2 Fungal database, which includes more than 500 validated sequences from different fungal species but not from dermatophytes. In the present study, we tested the MicroSeq D2 LSU rRNA Fungal Sequencing Kit by using it to identify dermatophyte species from patients referred to the mycological laboratory of the Department of Dermatology at the University Hospital in Lausanne, Switzerland (Table 1). Neotypes of different species and other reference strains (Table 2) were used for comparison of DNA sequences. This study allows the extension of the MicroSeq D2 Fungal database to the determination of dermatophytes.Isolates. Skin and nail scrapings and hair fragments were collected from patients with suspected mycoses. Routinely, one part of each sample was examine...

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Tinea capitis Dermatophytes: Susceptibility to Antifungal Drugs Tested in vitro and in vivo

Cited by 66 publications

References 14 publications

Phylogenetic analysis of Trichophyton mentagrophytes human and animal isolates based on MnSOD and ITS sequence comparison

Phylogenetic analysis of Trichophyton mentagrophytes human and animal isolates based on MnSOD and ITS sequence comparison

Collaborative Evaluation of Optimal Antifungal Susceptibility Testing Conditions for Dermatophytes

Identification of Dermatophyte Species by 28S Ribosomal DNA Sequencing with a Commercial Kit

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