Salmonella in humans and other animals

Salmonella enterica is a Gram-negative enteric pathogen that is responsible for over 120 million cases of infection world-wide. The species can be divided in six subspecies, and comprise over 2,000 serovars. The vast majority of Salmonella serovars can colonize a variety of hosts, including farm animals (chicken, cattle, pigs) that often transmit the infection to humans. A few serovars, however, are restricted to the human host, thus only colonize and infect humans. The first group of serovars are termed “non-typhoidal” Salmonella strains and primarily cause gastroenteritis in healthy individuals, although they may cause bacteremia in children, elderly, and immunocompromised patients. The second group of serovars are termed “typhoidal” Salmonella and cause typhoid fever, a disease characterized by fever and general malaise, and constipation more often than diarrhea. In my talk, I will give a broad overview of some mechanisms of pathogenicity employed by non-typhoidal and/or typhoidal Salmonella, with a focus on the following topics: 1) the mechanisms by which non-typhoidal Salmonella causes gastroenteritis; 2) the importance of host immunity in keeping non-typhoidal Salmonella localized to the gut; 3) why typhoidal Salmonella does not cause inflammatory diarrhea; 4) specific virulence mechanisms of typhoidal Salmonella; 5) mechanisms of typhoidal Salmonella host restrictions.