Merck Manual

Please confirm that you are a health care professional

honeypot link

Overview of Salmonella Infections


Larry M. Bush

, MD, FACP, Charles E. Schmidt College of Medicine, Florida Atlantic University;

Maria T. Vazquez-Pertejo

, MD, FACP, Wellington Regional Medical Center

Last full review/revision Feb 2020| Content last modified Feb 2020
Click here for Patient Education

The genus Salmonella is divided into 2 species, S. enterica and S. bongori, which include > 2400 known serotypes. Some of these serotypes are named. In such cases, common usage sometimes shortens the scientific name to include only the genus and serotype; for example, S. enterica, subspecies enterica, serotype Typhi is shortened to Salmonella Typhi.

Salmonella may also be divided into 3 groups based on how well the organism is adapted to human hosts:

  • Those highly adapted to humans and having no nonhuman hosts: This group includes S. Typhi and S. Paratyphi types A, B (also called S. Schottmülleri), and C (also called S. Hirschfeldii), which are pathogenic only in humans and commonly cause enteric (typhoid) fever.

  • Those adapted to nonhuman hosts or causing disease almost exclusively in animals. Some strains within this group—S. Dublin (cattle), S. Arizonae (reptiles), and S. Choleraesuis (swine)—also cause disease in humans.

  • Those with a broad host range: This group includes > 2000 serotypes (eg, S. Enteritidis, S. Typhimurium) that cause salmonella gastroenteritis and account for 85% of all Salmonella infections in the US.

Click here for Patient Education
NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
Professionals also read

Test your knowledge

Toxoplasmosis is infection with Toxoplasma gondii. The only known hosts of this organism are domestic cats and their relatives. Infection with T. gondii in humans can occur in various ways. Which of the following is the most common mode of infection in humans? 
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest