During the last few years, the number of cases of Trichophyton verrucosum isolation from humans suffering from mycoses has been constantly increasing, which is correlated with the presence of an increasing number of outdoor breeding farms. Farmers and their families as well as veterinarians and technicians involved in handling the animals are at a higher risk of infection. One of the most important aims of mycological diagnostics is epidemiological analysis. Typically, the history of the disease is not sufficient to indicate reliably and eliminate the outbreak of infection. PCR fingerprinting methods are a useful tool in this type of analysis, which is presented in this study. The main aim is to present diagnostic and epidemiological analyses of dermatophyte isolates from llamas and their breeder. In two llamas, round alopecia sites or ca. 2‐cm excoriations covered with thickened scaling epidermis were noticed at the border of the head and neck with a distinct tendency towards hair loss. Tinea unguium was noticed in a nail of the breeder's right hand. Direct analysis of the material from the clinical lesions revealed the presence of arthrospores. The macro‐ and micromorphology of the isolates were homogeneous and characteristic for T. verrucosum. The identification analysis based on the ITS sequences confirmed the previous morphological diagnostic examination. The MP‐PCR and MSP‐PCR analysis indicated high invariability of the genomes of the strains isolated from the human and animals. The epidemiological research has indicated an identical source of dermatophyte infection in the breeder and the lamas. To sum up, the number of pets and farm animals is increasing and dermatologists should always be informed about possible dermatophyte transmission sources. The possibility of transmission of zoophilic dermatophytes from humans to animals is a suggestion for further analysis; therefore, this type of transmission should be considered in dermatological studies.

Background Dermatomycoses are the most common fungal infections in the world affecting a significant part of the human and animal population. The majority of zoophilic infections in humans are caused by Trichophyton mentagrophytes. Currently, the first-line drug for both oral and topical therapy is terbinafine. However, an increasing number of cases that are difficult to be cured with this drug have been noted in Europe and Asia. Resistance to terbinafine and other allylamines is very rare and usually correlated with point mutations in the squalene epoxidase gene resulting in single amino acid substitutions in the enzyme, which is crucial in the ergosterol synthesis pathway. Purpose Here, we report terbinafine-resistant T. mentagrophytes isolates among which one was an etiological factor of tinea capitis in a man and three were obtained from asymptomatic foxes in Poland. Methods We used the CLSI protocol to determine antifungal susceptibility profiles of naftifine, amphotericin B, griseofulvin, ketoconazole, miconazole, itraconazole, voriconazole, and ciclopirox. Moreover, the squalene epoxidase gene of the terbinafine-resistant strains was sequenced and analysed. Results In the genomes of all four resistant strains exhibiting elevated MICs to terbinafine (16 to 32 µg/ml), single-point mutations leading to Leu393Phe substitution in the squalene epoxidase enzyme were revealed. Among the other tested substances, a MIC50 value of 1 µg/ml was shown only for griseofulvin. Conclusion Finally, our study revealed that the terbinafine resistance phenomenon might not be acquired by exposure to the drug but can be intrinsic. This is evidenced by the description of the terbinafine-resistant strains isolated from the asymptomatic animals.

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Dermatophytoses are skin diseases related to the infection of surface layers of skin and other keratinised structures such as hair and nails, caused by fungi referred to as dermatophytes. The scientific literature provides descriptions of over 50 dermatophytic species classified in the Trichophyton, Epidermophyton, Nannizzia, Arthroderma, Lophophyton, and Paraphyton genera. Dermatophytes are regarded as pathogens; they are not a component of skin microbiota and their occurrence in animals and humans cannot be considered natural. The review of the scientific literature regarding the occurrence and prevalence of dermatomycoses in companion animals revealed significant differences in the prevalence of the infections. Two main factors are most frequently assumed to have the greatest epidemiological importance, i.e. the animal origin and the type of infection. In this aspect, interesting data are provided by investigations of the fungal microbiota present in cat and dog fur. Interestingly, an anthropophilic species Trichophyton rubrum was found to be one of the species of dermatophytes colonising the skin of animals that did not present symptoms of infection. Is the carrier state of this species important in the epidemiology of human infections? Additionally, animal breeders and veterinarians claim that only certain breeds of dogs and cats manifest high sensitivity to dermatophyte infections. The pathomechanism of dermatophyte infections has not yet been fully elucidated; however, three main stages can be distinguished: adhesion of arthrospores to corneocytes, their germination and development of mycelium, and fungal penetration into keratinised tissues. Importantly, the dermatophyte life cycle ends before the appearance of the first symptoms of the infection, which may pose an epidemiological threat. Dermatophyte virulence factors include various exoenzymes, mainly keratinase, protease, lipase, phospho lipase, gelatinase, and DNase as well as toxins causing haemolysis responsible for nutrient supply to pathogens and persistence in the stratum corneum of the host. Clinical symptoms of the infection are external manifestations of the dermatophyte virulence factors.

The major problems in determining the causative factors of the high prevalence of dermatophytoses include the lack of a well-standardized antifungal susceptibility testing method, the low consistency of in vitro and clinical minimal inhibitory concentration values, the high genomic diversity of the population, and the unclear mechanism of pathogenicity. These factors are of particular importance when the disease is recalcitrant and relapses. Herein, we identified and characterized Trichophyton mentagrophytes isolates obtained from therapy-resistant cases in humans and animals. We used genomic diversity analysis of 17 human and 27 animal clinical isolates with the MP-PCR technique, determined their phenotypic enzymatic activity and host range, and performed antifungal susceptibility testing to currently available antifungal drugs from various chemical groups. Genomic diversity values of 35.3% and 33.3% were obtained for clinical isolates from humans and animals, respectively, yet without any relationship to the host species or antifungal drug to which resistance in therapy was revealed. The highest activity of keratinase enzymes was recorded for fox, guinea pig, and human hairs. These hosts can be considered as the main species in the host range of these isolates. A phenyl morpholine derivative, i.e. amorolfine, exhibited superior activity against strains obtained from both humans and animals with the lowest MIC50. Interestingly, high compliance of terbinafine in vitro resistance with clinical problems in the treatment with this substance was shown as well. The high resistance of dermatophytes to drugs is the main cause of the recalcitrance of the infection, whereas the other features of the fungus are less important.