How do you diagnose Salmonella infection

Diagnosis of Salmonella infection is undertaken by

a) Isolation of Salmonella -

Salmonella isolated using blood culture, organisms are isolated from blood stream at all stages of infection
Salmonella species are isolated mostly from 2nd week and 3rd week from stool and urine samples respectively.
Faeces and Urine are centrifuged and the deposits are enriched in Selenine F broth followed by inoculation in to Selective media Deoxycholate Citrate Agar (DCA)
The colonies are tested for presence of Salmonella #$#O#$# and #$#H#$# antigens by slide agglutination test, followed by biochemical testing.

b) Widal test : -

Widal test is done to detect Salmonella antibodies in the blood of infected person. Specific O and H antibodies of Salmonella are detected in blood.
Detection of Vi antibodies in the serum is diagnostic for Salmonella chronic carriers.
Fourfold increase in antibody level is used for confirming Salmonella infection.