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.

Nannizzia genus affected significantly more dogs (24.4%) than cats (7.1%) (P < .05). The ITS rDNA exhibited higher accuracy for identifying dermatophytes compared to phenotypic diagnosis, allowing the confirmation of the first reports of N. incurvata as an etiological agent of dermatophytosis in dogs and cats in Brazil.

Antimicrobial activity of topical dyes used in clinical veterinary ophthalmology.

OBJECTIVE: To evaluate in vitro the antibacterial effects of fluorescein, rose bengal, and lissamine green topical ophthalmic dyes against selected Gram-positive and Gram-negative bacteria, and to evaluate whether preserved or preservative-free fluorescein solutions are able to inhibit or potentiate bacterial growth. PROCEDURES: Susceptibility testing was performed using the Kirby-Bauer disk diffusion method plated with clinical ocular isolates of Staphylococcus aureus, Staphylococcus pseudintermedius, Streptococcus spp., Escherichia coli, and Pseudomonas aeruginosa. Bacterial growth inhibition was evaluated 24 hours following the addition of commercially available fluorescein, rose bengal, and lissamine green sterile strips. Antimicrobial effectiveness testing was performed by inoculation of compounded 1% dye solutions, both with and without preservatives (fluorescein and lissamine contained thiomersal, and rose bengal contained nipagin and nepazol), with the five previously mentioned bacteria. Growth was evaluated at days 7, 14, and 28. RESULTS: All dyes showed antibacterial activity against Gram-positive organisms. Preservative-free compounded 1% fluorescein solution inhibited growth of Gram-positive organisms but not of Gram-negative organisms. Preservative-free rose bengal and lissamine green inhibited growth of both types of organisms. CONCLUSIONS: Preferably, ocular surface samples for antimicrobial culture should be taken prior to the administration of topical dyes, due to their potential antibacterial activity, particularly if undiluted strips are applied directly or commercial fluorescein solutions are used and not immediately rinsed. Ophthalmic dye solutions containing preservative are safe from bacterial growth for up to 28 days if properly handled and stored. The use of preservative-free fluorescein solutions should be avoided and preservative-free rose bengal and lissamine green should be handled carefully.

Human adaptation and diversification in the Microsporum canis complex.

The Microsporum canis complex consists of one zoophilic species, M. canis, and two anthropophilic species, M. audouinii and M. ferrugineum. These species are the most widespread zoonotic pathogens causing dermatophytosis in cats and humans worldwide. To clarify the evolutionary relationship between the three species and explore the potential host shift process, this study used phylogenetic analysis, population structure analysis, multispecies coalescent analyses, determination of MAT idiomorph distribution, sexual crosses, and macromorphology and physicochemical features to address the above questions. The complex of Microsporum canis, M. audouinii and M. ferrugineum comprises 12 genotypes. MAT1-1 was present only in M. canis, while the anthropophilic entities contained MAT1-2. The pseudocleistothecia were yielded by the mating behaviour of M. canis and M. audouinii. Growth rates and lipase, keratinolysis and urea hydrolytic capacities of zoophilic M. canis isolates were all higher than those of anthropophilic strains; DNase activity of M. ferrugineum exceeded that of M. canis. The optimum growth temperature was 28 °C, but 22 °C favoured the development of macroconidia. Molecular data, physicochemical properties and phenotypes suggest the adaptation of zoophilic M. canis to anthropophilic M. ferrugineum, with M. audouinii in an intermediate position.