Which specimens are appropriate for testing to confirm exposure to Bacillus anthracis?

• A. Urine only
• B. Blood or pleural fluid
• C. Saliva only
• D. Cerebrospinal fluid only

Answer: (B)

Testing for exposure to Bacillus anthracis relies on specimens that are most likely to yield the organism or its DNA during acute infection. Blood is a primary target because anthrax commonly spread through the bloodstream, so blood cultures or PCR on blood can confirm infection. Pleural fluid is also valuable, especially in inhalational anthrax, where pleural involvement is common and the organism can be detected directly in the pleural space.

Urine and saliva are not reliable or routinely used for confirmation because the organism is not consistently detected in those fluids. Cerebrospinal fluid would only be tested if there are signs of meningitis, and it is not the general specimen for confirming exposure. Therefore, the best-confirmation specimens are blood or pleural fluid.