Epidemiology and pathogenic characterization of species of the genus Aeromonas

Identifier:  TDX:2935

Handle: https://hdl.handle.net/20.500.11797/TDX2935

Authors:  Fernández Bravo, Ana

Abstract:
The genus Aeromonas includes more than 32 species, some of which are distributed in the environment and are considered to be indigenous to aquatic systems. The main objective of this thesis was to contribute to a better knowledge of the epidemiology and pathogenicity of this genus. In this work we have investigated the presence of Aeromonas in different water sources demonstrating the method of skimmed milk flocculation used for virus detection, it seems to be a good method for the detection of these bacteria. In addition, the analysis of A. salmonicida, a species classically associated with fish diseases using an in vivo model, confirmed that this species can infect mammals with different levels of pathogenicity. Considering the increase of infections by Aeromonas in recent years, different collaborations with university hospitals have been carried out to investigated different cases . It was also shown that the use of MALDI-TOF for the identification of Aeromonas spp isolated from clinical cases and fish was not precise due to the deficiencies in the database. The use of genomes, their comparison and the development of new bioinformatic tools, proved to be useful to understand the potential function of A. lusitana and A. salmonicida in the environment. In this doctoral thesis the metallochaperone HypA previously described with role in tolerance to stomach acid in other pathogens was characterized and in the defense of Aeromonas against macrophages. In addition, the role of the ExoA toxin and the type VI secretion system (T6SS) in mixed infections that progress in a necrotizing fasciitis have been demonstrated, using several mutant strains. Finally, a study of the defense of human monocytes against Aeromonas was performed. The results showed a species-specific immune response, that was higher in the most prevalent clinical species.