Cat favus caused by Microsporum incurvatum comb. nov.: the clinical and histopathological features and molecular phylogeny

Dermatophytes and skin dermatophytoses in Southeast Asia-First epidemiological survey from Cambodia

BACKGROUND

Dermatomycoses count to the most frequent dermatoses in Cambodia.

OBJECTIVES

The aim of this survey was to investigate the occurrence of dermatophytes in this Southeast Asian country.

METHODS

From June 2017 to July 2018, skin scrapings were taken from 67 patients with superficial dermatophytosis for mycological diagnostics. Identification of dermatophytes was confirmed by sequencing of the 'internal transcribed spacer'-(ITS) region of the rDNA, and the gene of the Translation Elongation Factor (TEF)-1α.

RESULTS

Patients were suffering from tinea corporis and tinea inguinalis/cruris 42/67 (63%), tinea capitis/faciei 14/67 (21%), tinea corporis/capitis/faciei 6/67 (9%), tinea manuum/pedis 2/67 (3%), tinea pedis 2/67 (3%) and tinea manuum 1/67 (1%). Both, by culture and/or PCR, a dermatophyte was detected in 52 (78%) out of 67 samples. Culture positive were 42 (81%) of 52, PCR positive were 50 (96%). The following dermatophytes were found: Trichophyton (T.) rubrum, 36/52 strains (69%, 29 by culture), T. mentagrophytes/T. interdigitale (TM/TI) 9/52 (17%, six by culture) and Microsporum (M.) canis 5/52 strains (10%, by culture). One strain of Nannizzia (N.) incurvata 1/52 (2%) and N. nana 1/52 (2%) was isolated. Based on sequencing, we demonstrated that two T. mentagrophytes strains out of the nine TM/TI represented the new ITS genotype XXV Cambodia. We found one T. mentagrophytes strain genotype VIII (now, reclassified as T. indotineae). This isolate was terbinafine resistant, and it exhibited the amino acid substitution Phe397Leu in the squalene epoxidase. Three strains of T. interdigitale genotype II* were isolated.

CONCLUSION

This is the first survey on epidemiology of dermatophytes in Cambodia. Currently, T. rubrum represents the most frequent species in Cambodia. One Indian strain genotype VIII T. mentagrophytes was found. A highlight was the first description of the new T. mentagrophytes genotype XXV Cambodia.

Nannizzia species causing dermatophytosis in cats and dogs: First report of Nannizzia incurvata as an etiological agent in Brazil

Dermatophytosis is a superficial cutaneous infection, most commonly caused by fungal species such as Microsporum canis, Nannizzia gypsea (Microsporum gypseum), and Trichophyton mentagrophytes in dogs and cats. The zoonotic potential of these species is concerning, as companion animals are increasingly close to their owners. Therefore, the objectives of the study were to evaluate the current prevalence of Nannizzia-causing canine and feline dermatophytosis in Curitiba and Metropolitan Region, as well as perform phenotypic and phylogenetic characterizations of these isolates. Thus, 241 skin and fur samples from 163 dogs and 78 cats were analyzed from 2020 to 2021. The samples were obtained from animals of three sources: Veterinary Hospital of the Federal University of Paraná, animal shelters, and private clinics. The diagnosis was performed through phenotypic characterization and sequencing ITS rDNA region. Among 97 positive samples for dermatophytes, Nannizzia was identified in 14 (14.4%) samples, while other dermatophyte genera were found in the remaining 83 (85.6%) samples. Among the canine samples, nine (90%) were N. gypsea, and one (10%) was N. incurvata. Whereas in feline samples, three (75%) were N. gypsea, and one (25%) was N. incurvata. It was concluded that among 97 animals infected with dermatophytes, dogs (24.4%; 10/41) were significantly more affected by Nannizzia than cats (7.1%; 4/56) (P < .05). According to molecular analyses, the ITS rDNA region provided satisfactory results for species-level identification of Nannizzia, confirming the first report of N. incurvata as an etiological agent of canine and feline dermatophytosis in Brazil.

Epidemiology and Aetiology of Tinea Capitis in Wuhan and Its Surrounding Areas from 2011 Till the Present: A Single-Center Retrospective Study

Tinea capitis is still common in Wuhan, and there exists significant difference in its pathogen spectrum between this area and other parts of China. In the present study, we aimed to clarify the epidemiological characteristics of tinea capitis and changes of pathogen spectrum in Wuhan and its surrounding areas from 2011 to 2022, and further to present potential risk factors focusing on some major etiological agents. Briefly, a retrospective single-center survey was performed on 778 patients with tinea capitis from 2011 to 2022 in Wuhan, China. The isolated pathogens were identified to species level by morphological examination or by ITS sequencing. The data were collected and statistically analyzed by Fisher's exact test and Bonferroni method. Among all enrolled patients, the most common pathogen was Trichophyton violaceum in both child (310, 46.34%) and adult tinea capitis (71, 65.14%). There existed significant difference in pathogen spectrum between child and adult tinea capitis. Furthermore, black-dot type represented the most common type of tinea capitis for both children (303, 45.29%) and adults (71, 65.14%). Notably, the number of cases caused by Microsporum canis consecutively exceeded that caused by Trichophyton violaceum in children from Jan, 2020 to Jun, 2022. Additionally, we suggested a series of potential factors that might increase the risks of acquiring tinea capitis by focusing on several major agents. Considering the different risk factors related to specific pathogen, it was meaningful to adjust the measures against the spreading of tinea capitis according to the changes of pathogen distribution within recent years.

Nannizzia incurvata as a rare cause of favus and tinea corporis in Cambodia and Vietnam

Nannizzia (N.) incurvata (formerly Microsporum incurvatum) represents a geophilic dermatophyte which has been previously classified as belonging to the species complex of N. gypsea (formerly Microsporum gypseum). A 42-year-old Vietnamese female from Saxony, Germany, suffered from tinea corporis of the right buttock after she returned from a 2-week-visit to her homeland Vietnam. From skin scrapings of lesions, N. incurvata grew on Sabouraud's dextrose agar. Treatment by ciclopirox olamine cream twice daily for 4 weeks was successful. A 6-year-old Cambodian boy living near river Mekong with contact history to chicken, dogs and cattle suffered from tinea faciei and capitis. Symptoms of the favus-like tinea capitis and tinea faciei were erythema and scaly patches with areas of alopecia. N. incurvata grew on Sabouraud's dextrose agar. The boy was treated with oral terbinafine 125 mg daily, topical miconazole cream and ketoconazole shampoo. The symptoms healed within 4 weeks of treatment. Cultivation of the samples revealed growth of N. incurvata. For confirmation of species identification, the isolates were subject to sequencing of ITS (internal transcribed spacer) region of the rDNA, and addition of the "translation elongation factor 1 α" (TEF 1 α) gene. Sequencing of the ITS region showed 100% accordance with the sequence of N. incurvata deposited at the NCBI database under the accession number MF415405. N. incurvata is a rare, or might be underdiagnosed geophilic dermatophyte described in Sri Lanka and Vietnam until now. This is the first isolation of N. incurvata in Cambodia, and the first description of favus in a child due to this dermatophyte.

PRP8 intein in dermatophytes: Evolution and species identification

Dermatophytes are keratinophilic fungi belonging to the family Arthrodermataceae. Despite having a monophyletic origin, its systematics has always been complex and controversial. Sequencing of nuclear ribosomal ITS and D1/D2 rDNA has been proposed as an efficient tool for identifying species in this group of fungi, while multilocus analyses have been used for phylogenetic species recognition. However, the search for new markers, with sequence and size variation, which enable species identification in only one polymerase chain reaction (PCR) step, is very attractive. Inteins seems to fulfill these characteristics. They are self-splicing genetic elements present within housekeeping coding genes, such as PRP8, that codify the most important protein of the spliceosome. The PRP8 intein has been described for Microsporum canis in databases but has not been studied in dermatophytes in any other published work. Thus, our aim was to determine the potential of this intervening element for establishing phylogenetic relationships among dermatophytes and for identifying species. It was found that all studied species have a full-length PRP8 intein with a Homing Endonuclease belonging to the family LAGLIDADG. Phylogenetic analyses were consistent with other previous phylogenies, confirming Epidermophyton floccosum in the same clade of the Arthroderma gypseum complex, Microsporum audouinii close to M. canis, differentiating A. gypseum from Arthroderma incurvatum, and in addition, better defining the Trichophyton interdigitale and Trichophyton rubrum species grouping. Length polymorphism in the HE region enables identification of the most relevant Microsporum species by a simple PCR-electrophoresis assay. Intein PRP8 within dermatophytes is a powerful additional tool for identifying and systematizing dermatophytes.

Morpho-Molecular Characterization of Soil Inhabitant Dermatophytes from Ahvaz, Southwest of Iran, a High Occurrence of Microsporum fulvum

Occurrence and diversity of dermatophyte mycoflora in 298 soil samples from Ahvaz, Southwest of Iran was investigated by using the hair-baiting technique. The samples were collected during spring (n = 210) and autumn (n = 88) of 2015, and the fungal isolates were identified based on the macro- and micro-morphology of colonies and with further ITS-rDNA RFLP and sequencing. Totally, 60 soil samples (20.1%) were positive for dermatophyte growth whose pH varied from 7.0 to 7.9. The highest (26.6%) and the lowest (14.3%) recovery rates were from the animal resorts and the streets soils samples, respectively. Seasonally, 16.7% of the spring samples and 28.4% of the autumn samples were positive. Based on molecular identification, three species of two genera were identified viz. M. fulvum (n = 57), M. canis (n = 2) and zoophilic Trichophyton interdigitale (n = 1). As a specific goal in the study, differentiation of the species in Microsporum gypseum complex was established by measuring the mean length and width of macroconidia in some strains of M. gypseum, M. fulvum and M. incurvatum. Mean size for macroconidia length and width in three species showed that M. gypseum and M. incurvatum can morphologically be differentiated from M. fulvum but not from each other. M. fulvum was the most abundant species isolated from the soils of Ahvaz; however, to comprehensively specify the distribution pattern of geophilic dermatophytes in the soils of this city further investigations are needed. Identification based on micro-morphometric is not effective for species distinction in M. gypseum complex, while molecular procedures based on sequencing of certain DNA regions are the most reliable and applicable strategies for this purpose.

Dermatophytosis due to Microsporum incurvatum: Notification and Identification of a Neglected Pathogenic Species

A 4-year-old Iranian boy developed erythematous, itchy and annular lesion on his face. Microscopic examination of the scraped samples with 10 % potassium hydroxide (KOH) revealed fungal septate hyphae and arthroconidia. The etiological agent was found to be Microsporum gypseum in mycological examinations. Amplification and restriction digestion of the internal transcribed spacers (ITS) of rDNA was not helpful for identification, but in ITS sequencing the isolate showed 98 % homology to Microsporum incurvatum strain CBS 172.64. Empirical treatment of the patient with griseofulvin for 4 weeks was successful. Other than our isolate, the ITS1 sequences of 38 strains from related species were retrieved from GenBank and phylogenetic tree using maximum likelihood method was constructed. The case isolate clustered apart from other strains of M. incurvatum. Pairwise comparison of ITS1 showed intraspecies variations of 0-13 nucleotides among M. incurvatum strains and an extensive interspecies variation of 33-80 bp and remarkable interspecies size polymorphism between the three sister species in the M. gypseum complex. The high level of ITS1 intraspecific variation is suitable for species identification rather than phylogeographic analysis of M. gypseum complex.