Salmonella bacteria is discovered in stool cultures. Although blood cultures are rarely positive, bacteremia does occur in 5% of adults with Salmonella gastroenteritis and can result in hematogenous spread to the heart (endocarditis), spleen, bone (osteomyelitis), and joints (reactive arthritis).
What tests can be done to determine whether a person has Salmonellosis?
The diagnosis of salmonellosis is confirmed by cultures of stool or blood. In other words, specimens of blood or feces are placed in nutrient broth or on agar and incubated for 2-3 days. After that time, a trained microbiologist can recognize Salmonella bacteria if present by its unique characteristics.
However, blood cultures are often not performed and in most cases the blood stream is not infected. In the stool, the laboratory is challenged to pick out Salmonella from many other similar bacteria that are normally present. In addition, many persons submit cultures after they have started antibiotics, which may make it even more difficult for a microbiology lab to grow Salmonella. So, the diagnosis of salmonellosis may be problematic and many mild cases are culture negative.