| Congresso Brasileiro de Microbiologia 2023 | Resumo: 1140-1 | ||||
Resumo:The multidrug-resistant fungal pathogens belonging to the Candida haemulonii complex and the phylogenetically related species Candida auris are well-known for causing infections that are difficult to treat due to their multidrug-resistance profile. Candida auris is even more worrisome due to its ability to cause outbreaks in healthcare settings. These emerging yeasts produce a wide range of virulence factors that facilitate the development of the infectious process. In recent years, the aggregative phenotype has been receiving attention, as it is mainly associated with defects in cellular division and its possible involvement in helping the fungus to escape from host immune responses. In the present study, we initially investigated the aggregation ability of clinical isolates belonging to the C. haemulonii species complex (C. haemulonii sensu stricto [n = 5], C. duobushaemulonii [n = 4] and C. haemulonii var. vulnera [n = 3]) and C. auris (n = 6). Subsequently, we evaluated the effects of physicochemical factors on the fungal aggregation competence. The results demonstrated that cell aggregation was a typically time-dependent event, in which almost all studied fungal isolates of both the C. haemulonii species complex and C. auris exhibited high aggregation after 2 h of incubation at 37°C (% aggregation > 40%). After prolonged periods of incubation, aggregation remained time-dependent, and except for one isolate, all the others exhibited aggregation around 80% after 5 h and 90% after 24 h. Interestingly, the fungal cells forming the aggregates remained viable after all aggregation periods. Microscopic analyses revealed that the members of the C. haemulonii species complex exhibited clusters of cells even after vigorous vortex mixing at the beginning of the experiment (time 0 h), and these aggregates became noticeably larger after the incubation period, indicating the occurrence of significant cell-to-cell interactions. Candida auris displayed smaller cluster of cells than the C. haemulonii complex isolates at time 0 h, but they also increased in size and number of cells per aggregate after incubation. The aggregation of all isolates was not impacted by pH, temperature, β-mercaptoethanol (a protein-denaturing agent) and EDTA (a chelator agent). Conversely, the broad-spectrum proteases, proteinase K and trypsin, and the anionic detergent sodium dodecyl sulfate significantly diminished the fungal aggregation. Collectively, our results demonstrated that the aggregation ability in these opportunistic yeast pathogens is time-dependent, and surface proteins and hydrophobic interactions seem to mediate cell aggregation, since the presence of proteases and anionic detergent affected the aggregation ability. However, further studies are necessary to better elucidate the molecular aspects of this phenomenon.
Development Agencies: Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação de Amparo à Pesquisa no Estado do Rio de Janeiro (FAPERJ), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES - Financial code 001). Ramos, L.S. was supported by FAPERJ #E-26/202.397/2019 and #E-26/202.398/2019. Palavras-chave: Candida haemulonii clade, cell-cell interaction, emerging yeasts, physicochemical conditions, virulence Agência de fomento:CAPES, CNPq, FAPERJ | |||||