| Congresso Brasileiro de Microbiologia 2023 | Resumo: 648-1 | ||||
Resumo:INTRODUCTION Candida auris has recently drawn attention by its wide expression of virulence factors and resistance to clinically used antifungals, contributing to the high number of nosocomial infections. Few literature reports have explored the environmental microbiological control of this organism and its possible interactions with environmental hosts. One way to understand it is through the study of C. auris interaction with Acanthamoeba castellanii (Ac), which could trigger a fungal response to predation and enhanced expression of virulence factors required for the infection in superior hosts. Exploring this phenomenon could lid to understanding the environmental adaptation of this pathogen, microbiological control and new health surveillance strategies.
METHODOLOGY. The kinetics of the direct interaction between Ac and C. auris (MMC1, resistant and MMC2, susceptible phenotype) was explored in different proportions (10 pathogens: 1 Acanthamoeba 5:1; 2:1; 1:1) and intervals (up to 3 h) and analyzed by flow cytometry. Fungal viability (growth curves and CFU) was assessed to check the direct and indirect impact of Ac on C. auris, by co-incubating the fungus with the amoeba or its by-products, respectively, as conditioned supernatant or extracellular vesicles (EVs). Recovered C. auris from the distinct incubation conditions were evaluated regarding their adaptation to stress (oxidative, osmotic, high temperature and pH extremes) and sensitivity to antifungals (polyenes and azoles). Additionally, the virulence of C. auris recovered from Ac or grown in the presence/absence of Ac EVs and their products was compared in survival Galleria mellonella models.
RESULTS: MMC1 and MMC2 strains demonstrated distinct association rates with Ac, depending on factors such as time and multiplicity of infection (MOI). Both phenotypes reproduced within Ac, maintaining their viability even under predation. Upon recovery from Ac, the Ca MMC1 strain showed greater tolerance to oxidative and osmotic stress; however, it is noteworthy that the MMC2 strain showed greater tolerance both to oxidative and osmotic stress and higher temperatures, such as 37 and 42oC. Regarding drug susceptibility, analysis performed with the MMC1 strain confirmed its extreme resistance, with a minimum inhibitory concentration (MIC) of Amphotericin B 32 µg/mL, while the group exposed to Ac displayed a greater sensitivity (4 µg/mL). As for the MMC2 strain, incubation with Ac was able to induce resistance (from 0.25 g/mL in control to 1 g/mL upon interaction with Ac). C. auris passage through Ac was accompanied by an increase in biofilm formation capacity and in ergosterol levels by both strains. Furthermore, MMC1 and MMC2 strains displayed enhanced siderophores production. Lastly, the MMC1 strain recovered from Ac displayed a lower mortality rate of G. mellonella when compared to control, indicating a possible attenuation in virulence, while for the MMC2 strain there was a reversal of the phenotype.
CONCLUSIONS: The MMC2 strain, therefore more susceptible to predation, would be more prone to selective pressure, adaptation to stress and modification of its susceptibility to antifungal agents and virulence. Therefore, these possible phenotypic changes, caused by the contact with Ac and adaptation to stress, indicate the urgent need for the microbiological control strategies of emerging pathogens and their environmental hosts, as a possible pillar in the concept of One Health. Palavras-chave: Candida auris, Acanthamoeba castellanii, ADAPTATION TO STRESS, VIRULENCE Agência de fomento:FAPERJ projects (E-26/202.696/2018) and the National Council for Scientific and Technological Development (CNPq scholarship 309736/2021-8) | |||||