The main test used to diagnose listeriosis is routine bacterial culture of a sterile-site specimen, especially blood culture or cerebrospinal fluid culture when infection is suspected. Stool testing is not recommended for diagnosing listeriosis specifically, and some references also list PCR of blood or cultures from placenta/amniotic fluid in certain situations.

What that means

  • Blood culture is the most common test when listeriosis is suspected in a sick patient.
  • CSF culture is used if there are signs of meningitis or brain infection.
  • Stool tests may help look for other causes of gastrointestinal illness, but they do not confirm listeriosis.

In one line

If a doctor is trying to diagnose listeriosis, they usually look for Listeria in blood or another normally sterile body fluid by culture.