Salmonella

Salmonella is a motile, non-sporeforming, Gramnegative, rod-shaped bacterium in the family Enterobacteriaceae and the tribe Salmonellae. Non-motile variants include S. Gallinarum and S. Pullorum.

Typhoid fever

Genus Salmonella

• The genus Salmonella is divided into two species that can cause illness in humans:
•  S. enterica
•  S. bongori Salmonella enterica, which is of the greatest public health concern, is comprised of six subspecies:

1.  S. enterica subsp. enterica (I)
2.  S. enterica subsp. salamae (II)
3.  S. enterica subsp. arizonae (IIIa)
4.  S. enterica subsp. diarizonae (IIIb)
5.  S. enterica subsp. houtenae (IV)
6.  S. enterica subsp. indica (VI)

• Salmonella is further subdivided into serotypes, based on the Kaufmann-White typing scheme first published in 1934, which differentiates Salmonella strains by their surface and flagellar antigenic properties.
• Salmonella spp. are commonly referred to by their serotype names.

Diseases caused by salmonella

• Most types of Salmonella cause an illness called salmonellosis, which is the focus of this website.
• Some other types of Salmonella cause typhoid fever or paratyphoid fever.

Symptoms

• Most people with Salmonella infection have diarrhea, fever, and stomach cramps.
• Symptoms usually begin six hours to six days after infection and last four to seven days. However, some people do not develop symptoms for several weeks after infection and others experience symptoms for several weeks.
• Salmonella strains sometimes cause infection in urine, blood, bones, joints, or the nervous system (spinal fluid and brain), and can cause severe disease.
• Salmonella are a diverse group of bacteria.
• Scientists classify Salmonella into serotypes (types) by identifying structures on the bacteria’s surfaces. Although more than 2,500 serotypes have been described, fewer than 100 are known to cause human infections.

Diagnosis

Salmonella infection is diagnosed when a laboratory test detects Salmonella bacteria in a person’s stool (poop), body tissue, or fluids.

How is infection treated?

Most people recover from Salmonella infection within four to seven days without antibiotics. People who are sick with a Salmonella infection should drink extra fluids as long as diarrhea lasts.

Salmonella typhimurium

Antibiotic treatment is recommended for:

• People with severe illness
• People with a weakened immune system, such as from HIV infection or chemotherapy treatment
• Adults older than 50 who have medical problems, such as heart disease
• Infants (children younger than 12 months).
• Adults age 65 or older

Complications

• Most people with diarrhea caused by Salmonella recover completely, although some people’s bowel habits (frequency and consistency of poop) may not return to normal for a few months.
• Some people with Salmonella infection develop pain in their joints, called reactive arthritis, after the infection has ended. Reactive arthritis can last for months or years and can be difficult to treat. Some people with reactive arthritis develop irritation of the eyes and pain when urinating.

How do people get infected?

Salmonella live in the intestines of people and animals. People can get Salmonella infection from a variety of sources, including

• Eating contaminated food or drinking contaminated water
• Touching infected animals, their feces, or their environment

Risk factors

• Children under 5 years old are the most likely to get a Salmonella infection.
• Infants (children younger than 12 months) who are not breast fed are more likely to get a Salmonella infection.
• Infants, adults aged 65 and older, and people with a weakened immune system are the most likely to have severe infections.
• People taking certain medicines (for example, stomach acid reducers) are at increased risk of infection.

Antibiotic resistance and Salmonella?

• Resistance to essential antibiotics is increasing in Salmonella, which can limit treatment options for people with severe infections. 
• One way to slow down the development of antibiotic resistance is by appropriate use of antibiotics.

Salmonella Resources
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