Subtyping Options for Microsporum canis Using Microsatellites and MLST: A Case Study from Southern Italy

Microsporum canis is considered one of the most common zoophilic dermatophyte species causing infections in animals and humans worldwide. However, molecular epidemiological studies on this dermatophyte are still rare. In this study, we aimed to analyse the population structure and relationships between M. canis strains (n = 66) collected in southern Italy and those isolated from symptomatic and asymptomatic animals (cats, dogs and rabbits) and humans. For subtyping purposes, using multilocus sequence typing (MLST) and multilocus microsatellite typing (MLMT), we first used a limited set of strains to screen for variability. No intraspecies variability was detected in six out of the eight reference genes tested and only the ITS and IGS regions showed two and three sequence genotypes, respectively, resulting in five MLST genotypes. All of eight genes were, however, useful for discrimination among M. canis, M. audouinii and M. ferrugineum. In total, eighteen microsatellite genotypes (A–R) were recognized using MLMT based on six loci, allowing a subdivision of strains into two clusters based on the Bayesian iterative algorithm. Six MLMT genotypes were from multiple host species, while 12 genotypes were found only in one host. There were no statistically significant differences between clusters in terms of host spectrum and the presence or absence of lesions. Our results confirmed that the MLST approach is not useful for detailed subtyping and examining the population structure of M. canis, while microsatellite analysis is a powerful tool for conducting surveillance studies and gaining insight into the epidemiology of infections due to this pathogen.

Epidemiology of Dermatophytes Isolated from Clinical Samples in a Hospital in Eastern Saudi Arabia: A 20-Year Survey

Background Dermatophytes are group of fungi that cause superficial infections via enzymes that degrade keratin in human skin. Several factors, including climate, gender, age, lifestyle, human migration, cultural habits, and socioeconomic status influence the prevalence of dermatophyte infections. We analyzed the prevalence of dermatophyte isolates in a hospital in Eastern Saudi Arabia from 2000 to 2019. Methods The data on fungal cultures were obtained from the Laboratory Information System of the Mycology Laboratories at Johns Hopkins Aramco Healthcare, and were used for the analysis. Fungal isolates were examined microscopically for the presence of specialized hyphal structures and conidia. The Vitek® MS microbial identification system (biomerieux) was used if the culture type was not identified microscopically. Results Among the 10,021 samples analyzed, 3040 (30.33%) were positive for fungi and only 398 (3.97%) were dermatophytes. Microsporum species was the most common dermatophyte accounting for 50.5% (n = 201) followed by trichophyton with 36.9% (n = 147). The most common positive samples were scrapping (251, 63%) and hair (68, 17%). Culture positivity relative to the age groups revealed a cluster of positive dermatophyte species in children < 10 years of age with 215 (54%) of all cases and among 10–19 years of age with 60 (15) of the cases (p < 0.001). Microsporum species were the prevalent dermatophytes in patients < 10 years of age, while Epidermophyton species were the most frequent dermatophyte species in age groups 10–19, 20–29, and 30–39 years. However, Trichophyton species were the most frequent dermatophyte species in individuals 70–79 years. The percentage of Microsporum and Trichophyton species decreased significantly over time (p < 0.001). In addition, there was a significant seasonal variation in relation to Trichophyton species. A comparison between the most frequent species showed that there was no difference in relation to gender, but there was a difference in relation to the specimen type and age group. Conclusion Dermatophytosis was common among children and adolescent with the most common samples were scrapping and hair. There was a significant reduction in Microsporum and Trichophyton species over time.

Molecular Characterisation and Phylogenetic Analysis of Dermatophytic Fungi Isolated from Tinea Capitis in Northwest Nigeria Using Sequence of the 28S rRNA

The detection and identification of fungal DNA from clinical samples is one of the fundamental approaches in biomedicine. The incidence, distribution, and control of dermatophytes has progress significantly and the use of phylogenetic species concepts based on rRNA regions have enhanced the taxonomy of dermatophyte species; however, the use of 28S rDNA genes has certain limitations. This gene has been used in dermatophyte taxonomy with limited enumeration; we appraised the sequence disparity within and among groups of the species, the gene ranking in identification, phylogenetic analysis, and taxonomy of 32 strains of eight dermatophyte species. In this study, a set of primers was adopted to amplify the target followed by a partial sequencing of the rDNA. The utilization of a pairwise nucleotide differentiation, an affinity was observed among eight dermatophyte species, with disparity among species ranging from 0 to 197 base pair (bp). Intra-species bp differences were found within strains of Trichophyton eriotrephon, Trichophyton bullosum, Trichophyton simii (Trichophyton genus), Microsporum audouinii, and Trichophyton tonsurans (Microsporum and Trichophyton genus, respectively); however, only some strains of Trichophyton eriotrephon were found to be invariant having three genotypes. Trichophyton tonsurans exhibited most intra-species variability. The characterization and construction of a phylogenetic tree of 28S rDNA gene on dermatophyte species provide a bedrock of an additional finding of connections between species. However, 28S rRNA capture provides a novel method of effective and sensitive detection of dermatophytes lodged in human skin scale. We report for the first time the emergence of T. eriotrephon, T. bullosum, T. simii, T. benhamiae, and Ctenomyces serratus dermatophytes from Tinea capitis in Nigeria.

Dermatophytes: role of host genetics in the development of illness

Because dermatophytes and their hosts are so different, infection susceptibility is most likely the consequence of changes on both sides, as well as reciprocal adaptation. In addition, some studies have revealed a role for host genetics in the development of illness, including possible Mendelian inheritance patterns for dermatophytosis tendency. This paper emphasizes the complexity of the genetic link between dermatophytes and their natural and accidental hosts. According to a literature study, different ideas and methodologies may lead to different interpretations of this connection. Selecting an appropriate model for analysis and reasoning is a critical step in better understanding these disorders. A significant portion of the research is focused on the host's genetic and immunological response to dermatophyte infection. Future studies will require a broader exploration of the dermatophyte genome in combination with analysis of large phenotypically well-characterized populations of various dermatophyte species in order to identify the main factors mediating infection risk that can be targeted to disrupt host–pathogen interactions and used in therapies. As a result, both conceptually and practically, extensive study on the interactions between dermatophytes and their specific hosts, which comprise intricate molecular pathways, is critical. However, it is undeniable that genetic predisposition plays a crucial role in the susceptibility to dermatophyte infection.

Inhibition of Dermatophyte Fungi by Australian Jarrah Honey

Superficial dermatophyte infections, commonly known as tineas, are the most prevalent fungal ailment and are increasing in incidence, leading to an interest in alternative treatments. Many floral honeys possess antimicrobial activity due to high sugar, low pH, and the production of hydrogen peroxide (H2O2) from the activity of the bee-derived enzyme glucose oxidase. Australian jarrah (Eucalyptus marginata) honey produces particularly high levels of H2O2 and has been found to be potently antifungal. This study characterized the activity of jarrah honey on fungal dermatophyte species. Jarrah honey inhibited dermatophytes with minimum inhibitory concentrations (MICs) of 1.5–3.5% (w/v), which increased to ≥25% (w/v) when catalase was added. Microscopic analysis found jarrah honey inhibited the germination of Trichophyton rubrum conidia and scanning electron microscopy of mature T. rubrum hyphae after honey treatment revealed bulging and collapsed regions. When treated hyphae were stained using REDOX fluorophores these did not detect any internal oxidative stress, suggesting jarrah honey acts largely on the hyphal surface. Although H2O2 appears critical for the antifungal activity of jarrah honey and its action on fungal cells, these effects persisted when H2O2 was eliminated and could not be replicated using synthetic honey spiked with H2O2, indicating jarrah honey contains agents that augment antifungal activity.

Kerion celsi due to Microsporum audouinii: a severe form in an immunocompetent girl

A 9-year-old girl presented a large inflammatory cup-shaped scalp lesion with alopecia surrounded by pustules, dander, and suppuration associated with an occipital inflammatory lymphadenopathy for 1 month. Wood’s light exam was positive as well as KOH mount showing ectothrix type hair involvement. Hair and pus culture on Sabouraud dextrose agar (SDA) added with chloramphenicol and supplemented with cycloheximide isolated a dermatophyte species identified as Microsporum audouinii according to the colonies features. Species identification was confirmed by matrix-assisted laser desorption-ionization–time of flight mass spectrometry (MALDI–TOF MS) and the patient was treated for kerion celsi with terbinafine tablets 125 mg per day associated with a ketoconazole-based shampoo. The evolution was favorable, with hair regrowth after 2 months.

Evaluation of Dermatophyte Test Medium and Sabouraud Dextrose Agar for Isolation of Dermatophyte Species

Background and Objective: Dermatophyte infections require laboratory diagnosis before treatment is started. Although direct microscopy is routinely performed but culture of dermatophytes is the gold standard. However, it takes about 4 weeks for species identification on primary media. Our aim was to compare dermatophyte test medium (DTM) as a screening medium for the isolation of dermatophytes in comparison with sabouraud dextrose agar (SDA). Methods: It was a comparative study carried out at the Department of Microbiology of Post Graduate Medical Institute, Lahore over a period of nine months. Samples were collected from one hundred patients with clinically suspected dermatophytoses after taking informed written consent. The samples were examined microscopically and then inoculated on two types of culture media, one Sabouraud dextrose agar (SDA) with added chloramphenicol, gentacin and cycloheximide and other dermatophyte test medium (DTM) with added chlortetracycline, gentacin and cyclohexamide. Results: Fungal growth was observed in fifty-six samples on culture. Out of the fifty-six positive on cultures, nineteen were that of dermatophytes. Out of n = 100 patients, ten were positive on SDA while n = 14 dermatophyte species were able to grow on DTM. A significantly higher positivity (P ³ 0.05) for isolating dermatophytes was observed by DTM as compared to SDA. DTM was able to isolate (71%) of the dermatophytes in first 10 days. Isolation rate of dermatophyte species was higher (73.68%) on DTM as compared to SDA which was 52.6%. Conclusion: Authors recommend the use of dermatophyte test medium for the primary isolation and identification of dermatophyte species to be more effective and time saving.

Evaluation of anti-dermatophytic activity of medicinal plants derived products

<p class="abstract"><strong>Background: </strong>Dermatophytes are a group of closely related fungi which are able to invade the keratinized tissue skin, hair and nail. In this study different medicinal plants like <em>Melaleuca alternifolia, Zingiber officinale, Allium sativum, Azadirachta indica, Citrus limonum, Curcuma longa, Cocos nucifera</em> were used as antifungal agent against different dermatophyte species.</p><p class="abstract"><strong>Methods: </strong>A hospital-based study consisting of 320 patients clinically diagnosed having dermatophytic infection who reported to the Dermatology outpatient department (OPD), Adesh medical college, Bathinda was conducted for the period of 2 years. Socio-demographic and clinical information was collected and sample was taken from the edge of infected area which was then collected in 2 ml of Eppendorf. Extracts of medicinal plants were then explored against dermatophyte. The data was evaluated using appropriate statistical method.</p><p class="abstract"><strong>Results: </strong>All dermatophyte species were found sensitive for <em>Melaleuca alternifolia, Zingiber officinale and Allium sativum</em>. These medicinal plants showed very good results as antifungal against dermatophytes while <em>Azadirachta indica </em>and <em>Citrus limonum </em>were moderate sensitive and <em>Curcuma longa </em>and <em>Cocos nucifera </em>did not show any zone of inhibition around the well.</p><p class="abstract"><strong>Conclusions: </strong>This research provides a scientific validation for the use of these medicinal plants in the treatment of dermatophytic infection and could be used in future for dermatophytic infection and other skin infection.</p>

In-Vitro Activity of Nano Fluconazole and Conventional Flucon-azole against Clinically Important Dermatophytes

Background: Dermatophytosis is one of the most common fungal infections in humans. Antifungals such as fluconazole are effectively used for treating dermatophytosis; however, drug resistance was observed in many cases. Therefore, a newer treatment strategy is essential. Methods: This study (Conducted in the Laboratory of the School of Public Health, Tehran University of Medical Sciences, Tehran, Iran in 2018) evaluated the antifungal susceptibility of nano fluconazole compared to conventional fluconazole on dermatophyte isolates using CLSI M38-A2guidelines. Dermatophyte species isolated from clinical cases of dermatophytosis were identified using PCR sequencing techniques. Zeta potential and size of the nano particles containing fluconazole were measured; scanning electron microscope (SEM) was used to determine nano particle structure. Results: The size of liposomal fluconazole obtained was 88.9 12.14 nm with –20.12 3.8 mV for zeta potential. The encapsulation rate for fluconazole was 75.1 4.2%. MIC50 for the three tested species was 32, 16, and 8 μg/ml for Trichophyton interdigitale, T. rubrum, and Epidermophyton floccosum isolates, respectively. The corresponding values for nano fluconazole were 8 μg/ml for the three tested species. Conclusion: MIC value for nano-fluconazole was lower than conventional fluconazole in all dermatophytes species tested; therefore, nano-fluconazole could inhibit the growth of dermatophytes better than fluconazole at a lower concentration of the drug.