Emergência e susceptibilidade de leveduras em aves silvestres da Bahia

Abstract

DEEGAN, K. R. Emergence and susceptibility of yeasts in wild birds of Bahia. 2024. 188p. Tese (Doutora em Ciência Animal nos Trópicos) - Escola de Medicina Veterinária e Zootecnia – Universidade Federal da Bahia, 2024. Strengthening of relationships between humans and wild animals, invasion of wild areas, animal trafficking and presence of wild birds in urban and peri-urban environments contribute to increased risk of new zoonoses emergence. Study of wild microbiota is important for control and prevention of future health problems, for environmental conservation and for the discovery of new agents and resistance mechanisms. Bioprospecting of more effective and less toxic drugs for the host has been one of the major challenges in the development of antifungals. In this context, essential oils are a promising source of volatile secondary metabolites with antimicrobial activity. Given the importance of detecting and monitoring the occurrence of emerging and resistant yeasts in wild animals, this study aimed to identify, characterize and determine the susceptibility of yeasts in samples from free-ranging and captive wild animals. A systematic review was conducted to determine the frequency and spatial distribution of fungi detected in samples from wild birds. The molecular identification of yeasts was conducted by Sanger sequencing of the ITS1- 5.8S-ITS2 and D1-D2 regions. Protease production was determined by albumin degradation, and phospholipase production was evaluated with egg yolk agar medium. Cymbopogon densiflorus essential oil inflorescences were analyzed by GC-MS. The in vitro susceptibility of the isolates was evaluated against antifungals and C. densiflorus essential oil, using the broth microdilution method. Passerines, Psittaciformes and Accipitriformes were the bird orders with the greatest diversity of species sampled for fungal detection. Fungi of the species Candida albicans, Candida parapsilosis, Candida famata (currently Debaryomyces hansenii) and Aspergillus fumigatus were reported in the largest number of publications. Brazil stands out among the countries, with the highest number of publications and the greatest diversity of bird species sampled. The present study processed 68 samples of 55 free-living and captive wild birds of the species Anodorhynchus leari, Amazona aestiva and Amazona amazonica, in the municipalities of Canudos, Glória, Jeremoabo and Salvador, between August 2019 and April 2023. A total of 73 yeasts were sequenced, highlighting the species Debaryomyces hansenii, Candida parapsilosis, Lodderomyces xii elongisporus and Candida tropicalis as the most common, all reported as emerging yeasts, agents of fungemia in humans. Remarkably high phospholipase and protease activity was detected in 41.54% (27/65) and 24.24% (16/66) of the isolates, respectively. The susceptibility of 20 isolates was determined using the broth microdilution technique. 95% of the isolates were classified as resistant to at least one of the antifungal drugs, with 40% resistant to the three agents evaluated. The essential oil was able to inhibit the growth of all tested yeasts with MIC100 values between 0.004% and 0.125% (v/v) and fungicidal activity in 90% of the isolates. Compounds detected in highest concentration in C. densiflorus essential oil were: 2-Cyclohexen-1- ol, 3-methyl-6-(1-methylethenyl); D-Limonene; trans-p-mentha1(7),8-dien-2-ol; cis-p mentha-1(7),8-dien-2-ol; (-)-cis-Isopiperitenol and D-Carvone. Presence of monoterpenes in C. densiflorus may justify the antifungal activity observed in this study. Wild birds harbor emerging and opportunistic yeasts, with high expression of virulence factors and resistance to antifungals and are also a source of dissemination of new agents. Detecting emerging and multi-resistant species in wildlife is an essential tool to prevent the emergence of new pathogens in humans and domestic animals.