Candida tropicalis has been associated with invasive candidiasis, being the first or second most common non-Candida albicans Candida species isolated in humans with candidemia and candiduria, as well as being frequently isolated from healthy animals. This study aimed to characterize C. tropicalis isolates (n = 64) obtained from several animal species regarding antifungal susceptibility and production of virulence factors. The isolates were obtained from the microbiota of healthy animals (goats, n = 25; sheep, n = 6; psittacines, n = 14; rheas, n = 6; horses, n = 2; sirenians, n = 5; shrimp, n = 1), as well as from aquatic mammals found dead in the environment (cetaceans, n = 5). The isolates were subjected to in vitro susceptibility testing by broth microdilution according to the CLSI M27-A3 protocol against amphotericin B, caspofungin, itraconazole, and fluconazole. We also evaluated the virulence attributes, such as proteases and phospholipases, as well as biofilm formation. Resistance to itraconazole (n = 29) and fluconazole (n = 30) was detected among isolates from every source; resistance to both azoles was detected in 24 isolates, but none of them were resistant to amphotericin B and caspofungin. Protease production was detected in the majority of the isolates (n = 59), but phospholipase was produced by only a few of them (n = 6). The isolates showed different patterns in biofilm production, being considered strong producers (n = 41), moderate producers (n = 11), weak producers (n = 9) or non-producers (n = 3). In summary, C. tropicalis isolated from animals showed high rate of resistance to azoles, expressed virulence factors and therefore may represent a potential threat to human and animal health.

Respiratory infections are a common problem among equines and occur with variable rates of morbidity and mortality. Although some fungal species are considered primary agents of respiratory tract infections in several mammals, their relevance in respiratory diseases of equines is frequently neglected. In the present study, we performed an active search for Candida spp. in the nasal cavity of horses. The presence of Candida spp. was investigated through the use of nasal swabs that were streaked on culture media. These yeasts were identified through physiological testing and their in vitro antifungal susceptibility were also characterized. The analysis of the material from the nasal cavity of 97 randomly chosen horses resulted in the isolation of Candida spp. from 35 animals (36.08%), out of which 18 (32.14%) were C. famata, 14 (25%) C. parapsilosis, 12 (21.42%) Meyerozyma guilliermondii (C. guilliermondii), 11 (19.64%) C. tropicalis and 1 (1.78%) Wickerhamomyces anomalus (C. pelliculosa). The minimum inhibitory concentration (MIC) values ranged from 0.03125-1 μg/ml for amphotericin B; and from 0.03125-> 16 μg/ml and 0.125 to > 64 μg/ml for itraconazole and fluconazole, respectively. Resistance to fluconazole and itraconazole was observed among C. tropicalis (n = 3) and C. guilliermondii (n = 1). The data show a predominance of non-C. albicans Candida species in the nasal microbiota of healthy equines, including antifungal resistant isolates, reiterating the importance of monitoring fungal pathogens in these animals.

The results demonstrate that Candida from the ocular conjunctiva of horses can pose as a risk to animal health as they are capable of forming biofilms, which are commonly involved in fungal keratitis.

This was a cross-sectional study to investigate the antifungal susceptibility and production of virulence factors in strains of Candida isolated from the outlet and the lumen of the nasolacrimal duct of horses in the state of Ceará, Brazil. The samples were obtained from 103 horses. Sterile cotton swabs were used to collect the material from the outlet of the nasolacrimal duct and urethral probes, for the instillation of 2 ml of saline solution, were used to collect samples from the lumen of the nasolacrimal duct. A total of 77 Candida isolates were obtained, with C. famata, C. tropicalis, C. guilliermondii, and C. parapsilosis sensu lato as the most prevalent species. One isolate (C. glabrata) was resistant to caspofungin. One isolate was resistant only to fluconazole (C. parapsilosis sensu lato), 11 were resistant only to itraconazole (7 C. tropicalis, 2 C. guilliermondii, 1 C. famata, 1 C. parapsilosis sensu lato), while eight C. tropicalis showed resistance to both azoles. Overall, 28 isolates produced phospholipases and 12 produced proteases. These results highlight the importance of investigating the antifungal susceptibility and virulence trends of Candida spp. from the microbiota of the nasolacrimal duct of horses.