If blood cultures fail to recover Brucella, which other culture site may yield the organism?

If blood cultures fail to recover Brucella, which other culture site may yield the organism?

• A. Blood
• B. Urine
• C. Bone marrow
• D. Cerebrospinal fluid

Answer: (C)

Brucella is an intracellular pathogen that localizes in the reticuloendothelial system, especially the bone marrow. When bacteremia is intermittent or at low levels, blood cultures can fail to grow the organism, but the bone marrow often harbors a higher bacterial load. Culturing bone marrow aspirate therefore increases the chance of recovery and confirms the diagnosis. Urine and CSF can yield the organism in certain situations (urine variably; CSF mainly in neurobrucellosis), but they are less reliable than bone marrow for routine detection when blood cultures are negative.

Brucella is an intracellular pathogen that localizes in the reticuloendothelial system, especially the bone marrow. When bacteremia is intermittent or at low levels, blood cultures can fail to grow the organism, but the bone marrow often harbors a higher bacterial load. Culturing bone marrow aspirate therefore increases the chance of recovery and confirms the diagnosis. Urine and CSF can yield the organism in certain situations (urine variably; CSF mainly in neurobrucellosis), but they are less reliable than bone marrow for routine detection when blood cultures are negative.