Dermatophytosis in companion animals: A review

Zoonoses and pet owners: A survey on risk perception in Northern Italy

Veterinary and human medicine are focused on the issue of emerging and re-emerging diseases, which are especially represented by zoonosis that could be a threat for public health. Zoonotic risk may come from pets: some canine and/or feline viral, bacterial, parasitic, protozoal or mycotic diseases can be transmitted directly to humans. There are several strategies to prevent the transmission of such zoonosis, and among them vaccination plays an important role. Through a survey carried out in Northern Italy aimed to collect information regarding owners' knowledge and perception of the zoonotic risks associated with three zoonoses (rabies, leptospirosis, and dermatophytosis), it was demonstrated that dog owners tend to adhere more consistently to their pets' vaccination schedules and are more receptive to changes in vaccination scheduling compared to cat owners. This study also suggests that cat owners predominantly visit veterinarians for vaccination purposes, whereas dog owners seek veterinary services for a variety of reasons. The survey highlighted the ongoing need to enhance owners' understanding of zoonoses affecting their pets and also the protective role of vaccines. Veterinarians should undertake the responsibility of educating, reassuring, and informing pet owners about the significance of vaccines for their pets and for public health.

Expression of fungal and host markers in models of dermatophytosis on mice and human epidermis

Increasing resistance of dermatophytes against antifungals creates global public health problems, rendering essential a better understanding of virulence mechanisms and factors determining host-specificity of dermatophytes. Since dermatophytes switch from a saprophytic to a parasitic lifestyle by reprogramming gene expression, reliable experimental models are needed to investigate the pathogenesis of dermatophytosis. Here, a relevant mouse model of Trichophyton benhamiae dermatophytosis was assessed, together with a model based on reconstructed human epidermis (RHE), allowing their respective validation regarding fungal gene expressed during infection. The use of a standardized inoculum induced a natural-like superficial infection in mice. The severity and persistence of lesions enabled the assessment of infection markers, including mouse-specific pro-inflammatory molecules and fungal genes previously reported as potential virulence factors. Upregulated expression of fungal genes, including those encoding subtilisins, in infected RHE revealed that dermatophytes deploy similar processes as those observed during in vivo infection. The RHE model was then used to compare infections by anthropophilic Trichophyton rubrum and zoophilic T. benhamiae. Therefore, these two models represent complementary analytical tools to study the pathogenesis of acute dermatophytoses. In addition, we have identified certain fungal markers of infection and highlighted the existence of different mechanisms deployed by zoophilic versus anthropophilic dermatophytes.

A New Overview of Sex Bias in Fungal Infections

Fungal infections often disproportionately affect males over females. Since the NIH mandated in 2016 that researchers test their hypotheses in both biological sexes, numerous other fungal infections/colonizations have been found to exhibit sex-specific patterns. These patterns have been observed in various species, including mice, drosophila, cats, and bats, suggesting significant implications for understanding these diseases and developing treatments. Despite the recognition of this sex bias, primary research explaining its underlying causes or mechanisms remains limited. Current evidence suggests that potential causes might be linked to sex hormones, genetic expression, and evolutionary behaviors. This review consolidates recent data on sex bias in fungal infections or colonizations among different species and proposes future research directions to address existing gaps. Thus, this review advances the comprehension of the intricate relationships between biological sex, fungal infections, and broader health implications.

Dermatophytosis in Companion Animals in Portugal: A Comprehensive Epidemiological Retrospective Study of 12 Years (2012-2023)

Dermatophytosis, commonly referred to as ringworm, is a common superficial fungal infection in companion animals and humans. Between 2012 and 2023, plucked hair and scraped scale samples from domestic dogs and cats with clinical suspicion of dermatophytosis were collected from 355 veterinary medical centres across mainland Portugal. A total of 4716 animal samples were inoculated onto DERM agar, incubated at 25 °C for up to 4 weeks, and periodically examined macro- and micro-scopically to observe and evaluate fungal growth. Of these, 271 samples were removed due to contaminant fungi. Of the 568 positive cultures, the highest number were from the North (48.1%; 95% CI: 44.0-52.2%) and Centre (32.4%; 95% CI: 28.7-36.4%) regions. Microsporum canis was the most frequently isolated species (63.9%), followed by Trichophyton spp. (20.3%) and Nannizia gypsea (formerly Microsporum gypseum) (8.1%). Felines exhibited a higher frequency (17.4%) compared with dogs (9.1%) (p < 0.001). In dogs, the Yorkshire Terrier, West Highland White Terrier, Miniature Pinscher, Dalmatian and Miniature Schnauzer demonstrated a significant predisposition to dermatophytosis (p < 0.05). In cats, the Persian and Scottish Fold breeds were significantly predisposed (p < 0.05). No significant differences were found between sexes (p > 0.05). These findings underscore dermatophytosis as an increasing public health concern due to its zoonotic and contagious nature, providing comprehensive insights into the epidemiology of dermatophytosis in Portugal.

The Fungal Secretory Peptide Micasin Induces Itch by Activating MRGPRX1/C11/A1 on Peripheral Neurons

Pruritus is the leading symptom of dermatophytosis. Microsporium canis is one of the predominant dermatophytes causing dermatophytosis. However, the pruritogenic agents and the related molecular mechanisms of the dermatophyte M canis remain poorly understood. In this study, the secretion of the dermatophyte M canis was found to dose-dependently evoke itch in mice. The fungal peptide micasin secreted from M canis was then identified to elicit mouse significant scratching and itching responses. The peptide micasin was further revealed to directly activate mouse dorsal root ganglia neurons to mediate the nonhistaminergic itch. Knockout and antagonistic experiments demonstrated that MRGPRX1/C11/A1 rather than MRGPRX2/b2 activated by micasin contributed to pruritus. The chimeras and single-amino acid variants of MRGPRX1 showed that 3 domains (extracellular loop 3, transmembrane helical domain 3, and transmembrane helical domain 6) and 4 hydrophobic residues (Y99, F237, L240, and W241) of MRGPRX1 played the key role in micasin-triggered MRGPRX1 activation. Our study sheds light on the dermatophytosis-associated pruritus and may provide potential therapeutic targets and strategies against pruritus caused by dermatophytes.

Itraconazole in human medicine and veterinary practice

Diagnosis and management of fungal infections are challenging in both animals and humans, especially in immunologically weakened hosts. Due to its broad spectrum and safety profile when compared to other antifungals, itraconazole (ITZ) has been widely used in the treatment and prophylaxis of fungal infections, both in human and veterinary medicine. The dose and duration of management depend on factors such as the type of fungal pathogen, the site of infection, sensitivity to ITZ, chronic stages of the disease, the health status of the hosts, pharmacological interactions with other medications and the therapeutic protocol used. In veterinary practice, ITZ doses generally vary between 3 mg/kg and 50 mg/kg, once or twice a day. In humans, doses usually vary between 100 and 400 mg/day. As human and veterinary fungal infections are increasingly associated, and ITZ is one of the main medications used, this review addresses relevant aspects related to the use of this drug in both clinics, including case reports and different clinical aspects available in the literature.

Antifungal activity of aminopyrrolnitrin against Trichophyton verrucosum in a guinea pig model of dermatophytosis

BACKGROUND

Dermatophytosis is a common and major public health concern worldwide. Despite the increasing availability of antifungal drugs, relapses and untreated cases of dermatophyte infections are reported. Therefore, novel antifungal agents are required. Aminopyrrolnitrin (APRN) shows promise for dermatophytosis treatment because of its antifungal activity.

OBJECTIVES

This study aimed to assess the antifungal properties of APRN against Trichophyton verrucosum (T. verrucosum), in both laboratory settings and a guinea pig model.

METHODS

The minimum inhibitory concentrations (MICs) of APRN and enilconazole against T. verrucosum were determined according to the CLSI M38 method. The skins of 16 male guinea pigs were infected with 1.0 × 108 conidia of T. verrucosum and the animals were grouped into sets of four: negative control group (NC) received normal saline; positive control group (PC) received 2 μg/mL of enilconazole; and APRN4 and APRN8 received 4 and 8 μg/mL of APRN, respectively. Clinical, mycological and histological efficacies were measured after 10 days.

RESULTS

The MIC90 of APRN and enilconazole against T. verrucosum was 4 and 2 μg/mL, respectively. The clinical scores of PC, APRN4, and APRN8 were significantly lower than those of NC. Clinical and mycological efficacies were higher for APRN8, APRN4 and PC. No fungi were observed in the skin tissues of APRN4 and APRN8, while fungi were observed in 50% of the PC.

CONCLUSION

APRN showed antifungal activity against T. verrucosum in vitro and in vivo and is a potential candidate for the treatment of dermatophytosis.

Comparative assessment of regulated methods and PCR in the diagnosis of trichophytosis in veterinary mycology

Background

There is an increase in the incidence of human and animal infectious skin diseases of fungal etiology in the world. The main source of infecting the population has become agricultural and stray animals.

Aim

The objective of this study was to examine the morphophysiological and microbiological characteristics of pathogenic fungi belonging to the species Trichophyton verrucosum. This species is known to cause diseases in both humans and livestock in Kazakhstan. In addition, the study aimed to assess the feasibility of using the polymerase chain reaction (PCR) method for detecting T. verrucosum. This assessment was conducted in comparison to the outcomes of conventional laboratory diagnostic tests commonly employed for trichophytosis.

Methods

The research focused on analyzing 141 samples of pathological material obtained from calves in Almaty, Turkestan, and Kyzylorda regions. These calves exhibited clinical symptoms of skin disease. The study aimed to identify the causative agent using various techniques, including microscopic examination, microbiological methods involving the isolation of pure cultures, and PCR.

Results

The detection of the causative agent of dermatophytosis using conventional methods was relatively low, 86% for the microscopic method, and 79% for the microbiological method with the isolation of the culture of the pathogen. Extraction and detection of the genetic material of the causative agent of the disease for PCR was carried out according to the method developed by the authors. The effectiveness of the PCR method was 97.9%, which is significantly higher (p < 0.05) compared with the diagnostic effectiveness of conventional methods. The PCR method using specific primers identified the causative agent in 98% of cases, which significantly (p < 0.05) exceeded the results obtained using conventional diagnostic methods. Accordingly, the PCR method had better sensitivity and specificity indicators.

Conclusion

The conducted study recommends the method of PCR diagnosis of dermatophytosis for fast and reliable confirmation of the diagnosis of dermatophytosis in humans and animals in Kazakhstan.

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.

Molecular study of feline dermatophytosis and Toll-like receptor 2 and 4 gene expression in their lesions

BACKGROUND

Pattern recognition receptors (PRRs) as the recognition of pathogenic fungal structures induce the secretion of cytokines by immune systems. Toll-like receptors (TLRs) 2 and 4 are the main PRRs that recognize fungal components.

AIM

The present study aimed to assess the presence of dermatophyte species in symptomatic cats in a region of Iran and to investigate the expression of TLR-2 and 4 in cat lesions with dermatophytosis.

METHODS

A total of 105 cats suspected of dermatophytosis with skin lesions were examined. Samples were analysed by direct microscopy using potassium hydroxide (20%) and culture on Mycobiotic agar. Dermatophytes strains were confirmed by the polymerase chain reaction (PCR) amplification and then sequencing of the Internal Transcribed Spacer rDNA region. Also, for pathology and real-time PCR studies, skin biopsies were taken by sterile single-use biopsy punch from active ringworm lesions.

RESULTS

Dermatophytes were found in 41 felines. Based on the sequencing of all strains, Microsporum canis (80.48%, p < 0.05), Microsporum gypseum (17.07%) and Trichophyton mentagrophytes (2.43%) were the dermatophytes isolated from cultures. Cats under 1 year (78.04%) revealed a statistically significantly higher prevalence of infection (p < 0.05). Gene expression by real-time PCR revealed the increased TLR-2 and 4 mRNA levels in skin biopsies of cats with dermatophytosis.

CONCLUSIONS

M. canis is the most prevalent dermatophyte species isolated from feline dermatophytosis lesions. Increased expression of TLR-2 and TLR-4 mRNAs in cat skin biopsies suggests that these receptors are involved in the immune response by recognizing dermatophytosis.

Antifungal activity of Gracilaria corticata methanol extract against Trichophyton mentagrophytes, Microsporum canis, and Microsporum gypseum on rat dermatophytosis models

Background and Purpose

Dermatophytosis is one of the most prevalent zoonotic diseases. Increased resistance of dermatophytosis-causing pathogens against antidermatophytic agents highlights the need for alternative medicine with higher efficiency and lower side effects. In the present study, the in vitro antifungal activities of different concentrations of Gracilaria corticata methanol extract against Trichophyton mentagrophytes, Microsporum canis, and Microsporum gypseum were assessed and their efficacy was evaluated in rat dermatophytosis models.

Materials and Methods

The broth microdilution and well diffusion methods were used to determine the in vitro antidermatophytic activity. The in vivo study was carried out using 40 dermatophytosis-infected adults male Wistar rats. The animals were divided into 4 groups (5% and 10% G. corticata ointment, terbinafine, and Vaseline) and treated with ointment until complete recovery. The percentage of wound closure was calculated for each group.

Results

The results revealed that G. corticata methanol extract was effective to varying extents against the tested dermatophytes. The highest inhibitory activity of G. corticata was found against T. mentagrophytes with minimum inhibitory concentration and minimum fungicidal concentration values of 4 and 9 µg mL-1, respectively. The in vivo experiment revealed that 10% G. corticata ointment significantly accelerated skin lesions reduction and completely cured M. gypseum, T. mentagrophytes, and M. canis infections after 19, 25, and 38 days, respectively.

Conclusion

The methanol extract of G. corticata exhibited significant antifungal activity in vitro and in vivo, suggesting that it could be used as an alternative to antidermatophytic therapy in a dose-dependent manner.

Development, preparation, and evaluation of a novel non-adjuvanted polyvalent dermatophytes vaccine

Ringworm is a worldwide distributed contagious disease infecting both man and animals that constitute an economic, zoonotic, and health problem concern all over the world. During the last decade, attention has been directed to vaccination as an ideal approach to the control of such diseases. In the present study, non-adjuvanted polyvalent vaccines were prepared from locally isolated hot and virulent dermatophyte species, namely Trichophyton verrucosum (T. verrucosum), Trichophyton mentagrophytes (T. mentagrophytes), and Microsporum canis (M. canis) were immunologically evaluated. The prepared vaccine evaluation was focused on the aspects of immunogenicity and protective efficacy using guinea pigs. Both in its living or inactivated forms, the vaccine-induced significant humoral and cell-mediated immune responses and achieve proper protection of guinea pigs against challenging infections with homologous and heterologous dermatophyte strains. On the other hand, investigations on dermatophyte exo-keratinases showed that it was better produced and more expressed in a mineral-based medium containing pure keratin (3 g/L) than in the same medium with human hair supplementation (2.6 g/L). The maximum dermatophyte productivity of exo-keratinases was found to be between 18 and 21 days post-incubation. Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), two fractions with molecular weights of 40 kDa (fraction I) and 28 kDa (fraction II) have been identified in the culture filtrate of the three involved dermatophyte species. Both fractions demonstrated keratinolytic activity. The specific activity of the isolated keratinases (number of Keratinase units (KU)/mg protein) was stronger in fraction I, where it reached 18.75, 15.38, and 14 KU/mg protein as compared to 12.9, 8.74, and 12 KU/mg protein in fraction II of T. verrucosum, T. mentagrophytes, and M. canis, respectively. The dermatophyte exo-keratinases proved to be immunogenic as they stimulated high keratinase-specific antibody titers and induced strong delayed skin hypersensitivity reactions in vaccinated animals. Anti-keratinase-specific IgG was detected in sera of guinea pigs immunized with the inactivated or living polyvalent dermatophyte vaccines by a homemade enzyme-linked immunosorbent assay (ELISA) using dermatophyte exo-keratinases as coating antigen. The intradermal injection of dermatophyte exo-keratinases induced specific delayed skin reactions in guinea pigs immunized with the inactivated or the living polyvalent dermatophyte vaccines. The intradermal injection of dermatophyte exo-keratinases in the control non-sensitized guinea pigs was associated with itching, swelling, and bloody scar formation, however, no skin indurations were formed. The development of those post-exo-keratinases injection reactions in the control non-sensitized apparently healthy guinea pigs group, suggests an exo-keratinases possible role in the pathogenesis of dermatophytosis.

First study on molecular epidemiology of dermatophytosis in cats, dogs, and their companions in the Kurdistan region of Iraq

Background and Aim

Dermatophytosis is a zoonotic infection of the hair, skin, or nails in animals and humans caused by dermatophytes fungi. This study aimed to estimate the prevalence of dermatophytosis and its associated factors in cats, dogs, and humans in the Kurdistan region of Iraq.

Materials and Methods

Skin scraping samples were taken from cats, dogs, and humans with or without skin lesions. In total, 271 samples were collected; 133 from cats, 94 from dogs, and 44 from humans. The collected samples were cultured on dermatophyte test media for fungal isolation and molecular identification.

Results

The prevalence of the disease was 44.36%, 40.43%, and 65.91% in cats, dogs, and humans, respectively. Microsporum canis, the most frequently isolated dermatophyte, occurred in 94.92% of cats, 92.11% of dogs, and 100.0% of humans whereas, Trichophyton mentagrophytes was only isolated from 5.08% of cats to 7.89% of dogs. Animals and humans at younger ages were more susceptible to the infection. Males were more susceptible than females among animals, while the reverse was true in humans. Housed cats were at higher risk of dermatophytosis than outdoor-reared cats, whereas outdoor-reared dogs were at higher risk of dermatophytosis than indoor-reared dogs. The affected skin in animals and humans is significantly associated with higher prevalence rates of the disease. Contact with infected cats and dogs was associated with increased infection rates in humans. Patients with a history of coronavirus disease 2019 (COVID-19) were found to be at higher risk of dermatophytosis than those with no history of COVID-19.

Conclusion

Awareness should be raised among people about the zoonotic aspect of the disease, especially among those with COVID-19, to avoid contact with cats and dogs, who are at risk of the disease.

Fungal Flora in Asymptomatic Pet Guinea Pigs and Rabbits

Fungal skin diseases are well-recognized diseases with public health implications. The study provides a comprehensive overview and aims to determine the rate of positive fungal cultures to identify the most common fungal species in guinea pigs and rabbits and to determine the rate of asymptomatic carriers in healthy pet animals. This knowledge is essential for understanding disease transmission dynamics and epidemiological situation problems. A total of 167 animals (64 rabbits and 103 guinea pigs) were investigated in this study. The fungi of the genus Penicillium, Rhizopus, Mucor, Cladosporium, and Aspergillus were the most common in the examined animals, and they were isolated from 162 (97%) of the animals enrolled. No fungal growth was observed in 5 animals. In 15 cases (8.98%), we found pathogenic zoonotic dermatophytes (Trichophyton mentagrophytes), which caused several health problems in two humans in contact with affected animals. This study presents the prevalence of fungal flora in pet guinea pigs and rabbits in Slovakia.

Methylene blue-mediated antimicrobial photodynamic therapy for canine dermatophytosis caused by Microsporum canis: A successful case report with 6 months follow-up

Dermatophytosis is a superficial skin infection that widely effects companion animals. Miscrosporum canis is one of the most prevalent species isolated from dogs and cats, and because of the serious zoonotic potential, short-term treatment regimens are preferred to prevent the spread of disease either by direct contact or through contamination of the environment. Antimicrobial photodynamic therapy (APDT) has emerged as a promising strategy able to kill effectively a wide range of pathogens in a short period with minimal morbidity . In this case report, a 7-year-old male dog was diagnosed with dermatophytosis caused by M. canis. Methylene blue-mediated antimicrobial photodynamic therapy (MB-APDT) was applied over the lesions in two sessions with an interval of 7 days. The dog successfully healed, achieving a complete clinical cure after 21 days, without reports of recurrence after a follow-up period of 6 months. Therefore, MB-APDT could be a potential ally of small animal clinicians to treat superficial fungal diseases and should be further explored in Veterinary Medicine.