Which specimen types can be used for cryptococcal antigen testing?

Which specimen types can be used for cryptococcal antigen testing?

• A. Urine
• B. CSF or serum
• C. Saliva
• D. Blood culture

Answer: (B)

Cryptococcal antigen testing detects the capsular polysaccharide of Cryptococcus in body fluids, and it is validated for use in CSF and serum. These two specimens reliably contain detectable antigen when cryptococcal infection is present—CSF especially for cryptococcal meningitis, and serum for systemic or screening purposes in at-risk patients. Urine and saliva are not standard matrices because antigen levels in these fluids are inconsistent and the tests aren’t validated for them, leading to unreliable results. Blood culture is a culture method, not an antigen test, so it isn’t used for CrAg detection. Therefore, the best specimen types are CSF or serum.

Cryptococcal antigen testing detects the capsular polysaccharide of Cryptococcus in body fluids, and it is validated for use in CSF and serum. These two specimens reliably contain detectable antigen when cryptococcal infection is present—CSF especially for cryptococcal meningitis, and serum for systemic or screening purposes in at-risk patients. Urine and saliva are not standard matrices because antigen levels in these fluids are inconsistent and the tests aren’t validated for them, leading to unreliable results. Blood culture is a culture method, not an antigen test, so it isn’t used for CrAg detection. Therefore, the best specimen types are CSF or serum.