Campylobacter jejuni strains isolated in Brazil have important virulence related genes and survive to different stress conditions

Campylobacter jejuni has been reported as the leading bacterial pathogen that causes foodborne gastroenteritis in humans in many countries. This study aimed to assess the survival of 46 C. jejuni strains isolated from food (14), humans (18), and animals (14) in Brazil from 1996–2016 under different stress conditions, evaluate their invasion and survival capacity in Caco-2 cells and U-937 macrophages and determine virulence using the Galleria mellonella model for 23 selected strains. Furthermore, this study aimed to analyze the frequency of virulence related genes using WGS data. All 46 C. jejuni studied survived to acid stress with survival rates ranging from 29 to 100%. All studied strains survived to incubation in BHI with a final concentration of 7.5% NaCl with survival rates ranging from 3 to 100%. All strains showed growth in the temperatures analyzed with survival rates ranging from 5 to 100% at 4ºC and from 50 to 100% at 37ºC. Only two strains survived after 1 h of incubation under oxidative stress. All strains studied showed the ability to invade Caco-2 cells and to survive in U-937 macrophages. Regarding virulence in G. mellonella, 64% of strains presented virulence equal to or greater than the reference strain. The majority of the virulence genes detected was related to different stress conditions, adhesion, motility, and invasion. In conclusion, the pathogenic potential of the C. jejuni strains studied was highlighted and the results obtained may suggest that more rigorous control measures of this pathogen in food, especially poultry products are needed.