Serotypes and the Importance of Serotyping Salmonella

Salmonella have many different serotypes. Some serotypes are only found in one kind of animal or in a single place. Others are found in many different animals and all over the world. Some can cause especially severe illnesses when they infect people; while others cause milder illnesses.

Some groups of people, such as older adults, people with weakened immune systems, and children under five years old have a higher risk for Salmonella infection. Infections in these groups can be more severe, resulting in long-term health consequences or death.¹

More than 2,500 serotypes have been described for Salmonella; but, because they are rare, scientists know very little about most of them. Less than 100 serotypes account for most human infections. What we learn about the more common serotypes can help us better understand illness and the natural history of all the Salmonella strains.

Since the 1960s, public health scientists in the US have used serotyping to help find Salmonella outbreaks and track them to their sources. Laboratory experts serotype the Salmonella from infected people. When cases with one serotype increase, they suspect an outbreak and disease detectives start their investigation .

Serotyping has been the core of public health monitoring of Salmonella infections for over 50 years. Now, scientists use DNA testing to further divide each serotype into more subtypes and to detect more outbreaks. With the next generation of sequencing technology, advancements continue as the laboratory can find information about the species, serovar, and subtype of bacteria in just one test. Currently, at least two scientists must generate these three important pieces of information using three separate tests or more.²