The role of toxin-antitoxin systems

 

We study in detail the bacterium Salmonella. It is a gram negative bacterium, human pathogen and responsible of 155000 deaths worldwide in 2012. The most route of human infection by Salmonella is the food chain. For this reason the study of antibiotic resistance in Salmonella is a crucial issue. Moreover it needs to understand the mechanisms of antibiotic resistance spread in Salmonella, in particular Toxin-Antitoxin systems (TAs). Up to now 14 different TAs in Salmonella are known, of which only two are present to plasmid level and, thus, involved in post-segregation killing useful to spread of antibiotic resistance genes (ARGs). Our goals, to be achieved through a tight cooperation with the IZSVe of Padua, are i) to understand the role of TAs in diffusion in Salmonella strains by screening study using microbiological techniques and ii) to study the fitness cost of each genic element (TAs-ARG) during the human cell infection by molecular techniques.

The understanding of the epidemiology of ARGs and of AR selection systems like TAs, together with a deeper knowledge of the relations among phylotyping and accessory genes is of primary importance in order to reduce salmonellosis in clinical settings. We focus on the epidemiology of AR and TAs positive Salmonella enterica strains isolated from different sources and on the understanding of the mechanisms of AR gene transfer mediated by TAs. We are evaluating the role of TAs within the processes driving an infection in the intestinal human cells by Salmonella spp.

Photo courtesy of IZSVe. LINK