Dermatophytes isolated from asymptomatic dogs in Adana, Turkey: A preliminary study

The inhibitory effects of zinc oxide nanoparticles on clinical isolates of Microsporum canis in dogs and cats

INTRODUCTION

Microsporum canis is the most common dermatophyte infecting pets and their owners, and its long duration of treatment and increasing rate of drug resistance have caused the attention of researchers to be directed towards the use of nanoparticles and new alternatives for treatment. This study investigated the antifungal effects of zinc oxide (ZnO) nanoparticles on clinical isolates of M. canis in dogs and cats and subtilisin 1 (SUB1) gene expression.

MATERIALS AND METHODS

Zinc oxide nanoparticles were prepared using the wet chemical method at a concentration of 4000 ppm. Its antifungal potential was evaluated at concentrations of 62.5-4000 ppm by disk diffusion and microdilution methods against 10 isolates of M. canis. The effect of this product on SUB1 gene expression was investigated by quantitative real-time PCR method.

RESULTS

The results of the disk diffusion test showed that the highest inhibitory diameter was at the highest concentration of ZnO nanoparticles (34 mm), and the inhibitory zone was observed in dilutions up to 250 ppm. The minimum inhibitory concentration (MIC) of ZnO nanoparticles was between 250 and 500 ppm, and the minimum fungicidal concentration was between 500 and 1000 ppm. There was a significant reduction in SUB1 gene expression in sub-MIC concentration (125-250 ppm) (p < 0.05).

CONCLUSION

This study showed that ZnO nanoparticles have a concentration-dependent inhibitory effect on M. canis. Moreover, ZnO nanoparticles could decrease the expression of SUB1, an enzyme involved in fungi adhesion to the epidermis. Nevertheless, more studies must be done in the future to determine the possible side effects and safety of ZnO nanoparticles along with their efficacy in vivo.

An epidemiological study of animals dermatomycoses in Iran

OBJECTIVE

To determine the fungal species isolated from skin lesions of different animals suspected of having dermatomycoses and their prevalence in different regions of Iran.

MATERIALS AND METHODS

A total of 1011 animals (292 dogs, 229 cats, 168 horses, 100 camels, 98 cows, 60 squirrels, 37 birds, 15 sheep, 6 goats, 5 rabbits and 1 fox) suspected of having dermatomycoses were examined. The samples were obtained by plucking the hairs and feathers with forceps around the affected area and scraping the epidermal scales with a sterile scalpel blade. All collected samples were analyzed by direct microscopy and culture. Laboratory identification of the fungal isolates was based on their colonial, microscopic and biochemical characteristics.

RESULTS

Fungal agents were recovered from 553 (54.7%) animals suspected of having dermatomycoses. Of 553 confirmed cases, 255 (49.7%) were positive for dermatophytosis, 251 (45.4%) for Malassezia dermatitis, 14 (2.5%) for candidiasis, 12 (2.2%) for aspergillosis and 1 (0.2%) for zygomycosis. Cats (36.3%) were the most prevalent infected animals, followed by camels (13.4%), dogs (12.8%), horses (12.5%), cows (12.3%), squirrels (5.4%), birds (3.6%), sheep (2%), goats (1.1%), rabbits (0.4%) and fox (0.2%). Microsporum canis (M. canis) was the most frequent fungus isolated from dogs and fox, Malassezia pachydermatis (M. pachydermatis) from cats, horses and squirrels, Trichophyton verrucosum (T. verrucosum) from cows and camels, T. mentagrophytes var. mentagrophytes from sheep, goats and rabbits, and Aspergillus fumigatus (A. fumigatus) from birds.

CONCLUSION

The results suggested that periodic screening of animals suspected of having dermatomycoses and necessary treatments could help in the management of their public health problem.

Detection of seasonal asymptomatic dermatophytes in Van cats

The Van cat is a domestic landrace found in the Van province of eastern Turkey. In this study, we aimed to determine the seasonal carriage of dermatophytes in Van cats without clinical lesions. A total of 264 hair specimens were collected from clinically healthy cats in and around the Van Province. Of these samples, 30.3% were obtained in spring, 30.6% in summer, 16.6% in autumn, and 22.3% in winter; 45.1% of samples were from male cats and the rest from female ones. Of the studied cats, 118 were younger than 1 year, 78 were 1-3 years old, and 68 were older than 3 years. The specimens were subjected to direct microscopic examination with 15% potassium hydroxide and cultured on Sabouraud dextrose agar and dermatophyte test medium supplemented with cycloheximide and chloramphenicol. Dermatophyte identification was carried out based on macroscopic and microscopic colony morphology, urease activities, in vitro hair perforation test, growth at 37°C, and pigmentation on corn meal agar. Dermatophytes were isolated from 19 (7.1%) of the 264 specimens examined. The most frequently isolated fungi were Trichophyton terrestre (4.1%), followed by Microsporum gypseum (1.1%), M. nanum (1.1%), and T. mentagrophytes (0.7%), and these fungi may represent a health risk for humans in contact with clinically healthy Van cats. M. canis was not isolated from any of the specimens. Our results show no significant (p>0.05) association between carriage of dermatophytes and the gender of cats. The carriage rate of dermatophytes was high in spring and winter, and the only possible risk factor for infection was age of the animal.

Dermatophytoses in domesticated animals

Dermatophytes are among the most frequent causes of ringworm infections in domesticated animals. They are known to serve as reservoirs of the zoophilic dermatophytes and these infections have important zoonotic implication. In Nigeria and probably West Africa, there are not many studies on the incidence of dermatophytosis in domesticated animals. In the current study, 538 domesticated animals with clinically suggestive lesions were investigated for dermatophytes. Identification of dermatophyte species was performed by macro- and micro morphological examination of colonies and by biochemical methods. In the cases of isolates that had atypical morphology and/or biochemical test results, the rDNA internal transcribed spacer region 2 (ITS 2) sequencing was performed. Out of this number, 214 (39.8%) were found to be colonized by a variety of ten species of dermatophytes. M. canis was the most frequently isolated species (37.4%), followed by T. mentagrophytes (22.9%) and T. verrucosum (15.9%). M. persicolor and T. gallinae were jointly the least species isolated with a frequency of 0.55% respectively. The recovery of dermatophyte isolates previously shown to be common etiological agents of dermatophytosis especially from children in the same region suggests that animal to human transmission may be common. Possible implications and recommendations are discussed.