Evaluación de cambios fenotípicos en cepas de Salmonella Infantis tras la adquisición de resistencia al bacteriófago 35fd

Abstract

Salmonella enterica serotype Infantis (SI) is a zoonotic pathogen of global relevance, mainly associated with poultry products. This microorganism presents a remarkable resistance to third generation antibiotics, key drugs in the treatment of bacterial infections. Its ability to develop resistance has led to its expansion and replacement of other more prevalent serotypes worldwide, a phenomenon facilitated by the presence of a megaplasmid. Although alternatives have been explored against this pathogen, such as the use of bacteriophages, the high mutation rate of the bacteria can induce resistance to lysis mediated by these phages, which complicates their disinfection. Investigating the interaction with phages and their evolution is crucial for the development of disinfection protocols against SI. In the present project, phenotypic changes (growth curves, presence of the megaplasmid and resistance to different antibiotics) were evaluated in three different strains of SI exposed to the bacteriophage Felix35fd. Two mutant strains were obtained: GC2 and PO2, where the increase of resistance towards antibiotics up to 8 times their initial concentration and the importance of the megaplasmid for their survival stand out. Keywords: Salmonella Infantis, bacteriophage 35fd, resistance, megaplasmid, antibiotics.