Globally, Campylobacter is the most common cause of bacterial gastroenteritis in humans. Outbreaks of campylobacteriosis have been reported in Sweden in the recent years, despite measures being applied by the poultry industry. Our purpose is to investigate Campylobacter strains from Swedish outbreaks and identify factors that allow these strains to spread and persist in the production chain. Phenotypic characteristics will be defined and compared to non-outbreak strains and coupled to genotypic characteristics to investigate what is behind their success to cause outbreaks in humans. We will investigate tolerance and adaption mechanisms against various stress factors, e.g. dehydration, oxygen and freezing, and the ability to cause infection in human epithelial cells. The findings will contribute scientific knowledge on why certain strains are more likely to cause outbreaks and form recommendations for prevention of Campylobacter in the broiler chicken production.