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Aetiology and Laboratory Diagnosis
Published in Raimo E Suhonen, Rodney P R Dawber, David H Ellis, Fungal Infections of the Skin, Hair and Nails, 2020
Raimo E Suhonen, Rodney P R Dawber, David H Ellis
Trichophyton tonsurans is an anthropophilic fungus with a worldwide distribution that causes inflammatory or chronic non-inflammatory finely scaling lesions of skin, nails and scalp. Invaded hairs show an endothrix infection and do not fluoresce under Wood’s ultraviolet light. Key features include microscopic morphology, culture characteristics, endothrix invasion of hairs and partial thiamine requirement (Figure 1.9(a) and (b)).
Geriatric hair and scalp disorders
Published in Robert A. Norman, Geriatric Dermatology, 2020
In North America Trichophyton tonsurans is becoming the most common causative agent of tinea capitis, followed by Microsporum canis. Microsporum audouinii, formerly the most common cause of tinea capitis in the United States, typically occurred in prepubertal children and cleared spontaneously in postpubertal adolescence. Tinea capitis caused by Trichophyton tonsurans may persist into adulthood and may affect multiple generations. In Europe Trichophyton violaceum and Microsporum canis have replaced Trichophyton schoenleinii as the most frequent etiologic agents.
Dermatophytosis
Published in Mahmoud A. Ghannoum, John R. Perfect, Antifungal Therapy, 2019
Mahmoud A. Ghannoum, Iman Salem, Nancy Isham
Trichophyton rubrum is the most prevalent pathogen and most common etiologic agent in the United States for most dermatophytic infections except tinea capitis and fingernail onychomycosis. A recent epidemiological study in the United States from 1999 to 2002 reported increasing incidence of T. rubrum in onychomycosis, tinea corporis, tinea cruris, tinea manuum, and tinea pedis [6]. Trichophyton tonsurans and Candida albicans, on the other hand, were the predominant species for tinea capitis and fingernail onychomycosis, respectively. The primary etiologic agents for the various dermatophytic infections are listed in Table 15.1.
Inhibitory effect of proteinase K against dermatophyte biofilms: an alternative for increasing the antifungal effects of terbinafine and griseofulvin
Published in Biofouling, 2022
Raimunda Sâmia Nogueira Brilhante, Raissa Geovanna Pereira Lopes, Lara de Aguiar, Jonathas Sales de Oliveira, Géssica dos Santos Araújo, Germana Costa Paixão, Waldemiro de Aquino Pereira-Neto, Rosemayre Souza Freire, João Victor Serra Nunes, Renan Pereira de Lima, Flávia Almeida Santos, José Júlio Costa Sidrim, Marcos Fábio Gadelha Rocha
Fourteen dermatophyte strains were used (three M. canis, five T. tonsurans, four Trichophyton mentagrophytes, one Trichophyton rubrum and one E. floccosum). These strains were obtained from the culture collection of the Specialized Medical Mycology Center of the Federal University of Ceará, Brazil (Table 1). Initially, the strains were grown on 2% Sabouraud dextrose agar supplemented with 0.1% chloramphenicol (Difco-Dickinson, Detroit, MI, USA), and incubated at 28 °C for 7–15 days. Then, these strains were identified through morphological features of the colonies and micromorphological features under optical light microscopy, using lactophenol blue cotton. Finally, the strains were seeded on potato dextrose agar (Difco-Dickinson) and maintained at 28 °C (Brilhante et al. 2018b). The strains Candida krusei ATCC 6258, Trichophyton tonsurans ATCC 28942 and Trichophyton mentagrophytes CEMM-05-06-115 were used as controls in the antifungal susceptibility assay (Brilhante et al. 2018b, 2021; Castelo-Branco et al. 2020).
Nanotechnological interventions in dermatophytosis: from oral to topical, a fresh perspective
Published in Expert Opinion on Drug Delivery, 2019
Riya Bangia, Gajanand Sharma, Sunil Dogra, Om Prakash Katare
There are around 40 species of dermatophytes that can affect humans. The most prevalent ones are Trichophyton rubrum, Trichophyton tonsurans, and Microsporum canis [3–5]. The dermatophytes are categorized into three genera, namely, Trichophyton, Microsporum, and Epidermophyton [6]. The dermatophytes evolve according to the geographical locations and socioeconomic conditions [7]. Around 100 years ago, Epidermophyton floccosum, Trichophyton schoenleinii, and Microsporum audouinii constituted the major group of pathogens causing superficial fungal diseases, whereas their number decreased significantly since the mid-twentieth century and are nowadays restricted to some less-developed nations. However, frequency of some other pathogens, including T. rubrum, T. tonsurans, Trichophyton interdigitale, and M. canis, rose steadily and became the major species across the globe. In some regions of Europe, Asia, and Africa, other dermatophytes, including Trichophyton verrucosum, Trichophyton violaceum, and M. ferrugineum, are majorly endemic [8]. As per the current scenario, T. rubrum is the major pathogen responsible for skin and nail fungal infections worldwide, while T. violaceum (Eastern Europe, Africa, and Asia), M. canis (most regions of Europe and Asia), and T. tonsurans (the United Kingdom and North/South America) for tinea capitis [8–15].
Understanding the genetic basis of immune responses to fungal infection
Published in Expert Review of Anti-infective Therapy, 2022
Samuel M. Gonçalves, Cristina Cunha, Agostinho Carvalho
By resorting to arrays that contain millions of genetic variants, the comparison of patient and matched control genomes through genome-wide association studies (GWAS) has driven the initial unbiased efforts to identify variants associated with fungal infection. The first example was provided by a study in which the genome of children with either frequent or occasional infection with Trichophyton tonsurans was sequenced, with several genes involved in leukocyte function, remodeling of extracellular matrix and wound repair, and cutaneous permeability being found to account for over 60% of the variability in infection rates [86]. Another GWAS based on the use of the Immunochip SNP array identified three new susceptibility loci for candidemia, namely CD58, late cornified envelope 4A (LCE4A)-C1orf68, and T cell activation RhoGTPase activating protein (TAGAP) [87]. Functional analysis of the implicated genes and variants using in vitro and mouse models of infection confirmed their role in antifungal effector functions, including cytokine production and inhibition of fungal germination. Of note, these markers overlapped with other immune-mediated diseases besides candidemia, suggesting that the genetic architecture of autoimmune diseases in modern human populations may have been evolutionarily driven by exposure to pathogens. More recently, a GWAS of volunteers from the 23andMe database identified significant associations between yeast infection and variants downstream of protein kinase C eta type (PRKCH), and within desmoglein 1 (DSG1) and C14orf177 [88]. Although African populations are underrepresented in studies of genetic susceptibility, a GWAS of cryptococcosis in HIV patients of African descent identified several loci upstream of the macrophage colony-stimulating factor (CSF1) that were significantly associated with susceptibility to cryptococcosis [89].