Aims:  To find new antifungal agents among essential oils from Brazilian Croton species. Methods and Results:  Plant leaves were steam distilled and the obtained essential oils were analyzed by gas chromatography/mass spectroscopy. The main constituents were estragole and anethole for Croton zehntneri, methyl‐eugenol and bicyclogermacrene for Croton nepetaefolius and spathulenol and bicyclogermacrene for Croton argyrophylloides. The antifungal activity of essential oils was evaluated against Candida albicans, Candida tropicalis and Microsporum canis by the agar‐well diffusion method and the minimum inhibitory concentration (MIC) by the broth microdilution method. Essential oils of Croton species demonstrated better activity against M. canis. Among the three plants C. argyrophylloides showed the best results, with MIC ranging from 9 to 19 μg ml−1. The acute administration of the essential oil up to 3 g kg−1 by the oral route to mice was devoid of overt toxicity. Conclusions:  The studied essential oils are active in vitro against the dermatophyte M. canis and present relative lack of acute toxicity in vivo. Significance and Impact of the Study:  Because of its antifungal activity and low toxicity, the essential oils of studied Croton species are promising sources for new phytotherapeutic agents to treat dermatophytosis.

Cockatiels are the world's second most popular psittacine pet bird, but no data characterizing their gastrointestinal microbiota have been found. Thus, the aim of this work was to characterize the yeast gastrointestinal microbiota of cockatiels and to evaluate the relevance of cockatiels as carriers of potentially pathogenic yeasts. A total of 60 cockatiels, from 15 different premises, were assessed. A thorough clinical examination was performed with each bird, and samples were collected from oral cavity, crop and cloaca. The stools were collected from cages where the birds were kept. The isolates were identified according to morphological and biochemical characteristics. Yeasts were isolated from at least one anatomical site of 65 % of the birds and 64.3 % of the stool samples. The oral cavity (53.3 %) and the crop (58.3 %) were the anatomical sites with the highest prevalence and the highest number of yeast isolates. Overall, 120 yeast isolates, belonging to 13 species, were obtained. The most frequently isolated species were Candida albicans, with 39 (32.5 %) isolates, followed by Candida tropicalis (20 %), Trichosporon asteroides (12.5 %), Candida famata (10 %) and others. Mixed yeast colonies were isolated from 23.3 % of the birds and C. albicans was seldom found in association with other species (P,0.05). The results of this work demonstrated that cockatiels harbour potentially pathogenic yeasts throughout their gastrointestinal tract and in stools, and are prone to disseminating them in the environment.

Tyrosol is a quorum-sensing molecule of Candida albicans able to induce hyphal development in the early and intermediate stages of biofilm growth. In the present study, we evaluated the effect of high concentrations of exogenous tyrosol on planktonic cells and biofilms of C. albicans (n = 10) and C. tropicalis (n = 10), and investigated whether tyrosol could be synergic to antifungals that target cellular ergosterol. Antifungal susceptibility and drug interaction against planktonic cells were investigated by the broth microdilution method. Tyrosol was able to inhibit planktonic cells, with MIC values ranging from 2.5 to 5.0 mM for both species. Synergism was observed between tyrosol/amphotericin B (11/20 strains), tyrosol/itraconazole (18/20 strains) and tyrosol/fluconazole (18/20 strains). Exogenous tyrosol alone or combined with antifungals at both 10 × MIC and 50 × MIC were able to reduce biofilm of both Candida species. Mature biofilms were susceptible to tyrosol alone at 50 × MIC or combined with amphotericin at both 10 × MIC and 50 × MIC. On the other hand, tyrosol plus azoles at both 10 × MIC and 50 × MIC enhanced biofilm growth.

This study aimed at evaluating the in vitro antifungal susceptibility of Candida albicans isolates obtained during necropsy of a wild Brazilian porcupine and the mechanism of azole resistance. Initially, we investigated the in vitro susceptibility of the three isolates to amphotericin B, caspofungin, fluconazole, itraconazole, ketoconazole and voriconazole. Afterwards, three sub-inhibitory concentrations (47, 21 and 12 mg/l) of promethazine, an efflux pump inhibitor, were tested in combination with the antifungal drugs in order to evaluate the role of these pumps in the development of antifungal resistance. In addition, the three isolates were submitted to RAPD-PCR and M13-fingerprinting analyses. The minimum inhibitory concentrations (MICs) obtained with the isolates were 1, 0.03125, 250, 125, 8 and 250 mg/l for amphotericin B, caspofungin, fluconazole, itraconazole, ketoconazole and voriconazole, respectively, and the isolates were found to be resistant to all tested azoles. The addition of the three subinhibitory concentrations of promethazine resulted in statistically significant (P < 0.05) reductions in the MICs for all tested drugs, with decreases to azoles being statistically greater than those for amphotericin B and caspofungin (P < 0.05). The molecular analyses showed a genetic similarity among the three tested isolates, suggesting the occurrence of candidemia in the studied animal. These findings highlight the importance of monitoring antifungal susceptibility of Candida spp. from veterinary sources, especially as they may indicate the occurrence of primary azole resistance even in wild animals.

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