In suspected brucellosis, the optimal specimen to be collected for the isolation of the etiologic agent is

• A. Urine
• B. Cerebrospinal fluid
• C. Nasopharyngeal exudates
• D. Blood

Answer: (D)

During acute brucellosis, Brucella bacteria circulate in the blood, so a blood culture is the most reliable way to recover the organism for isolation. This bacteremia makes blood the first-line specimen for culture-based diagnosis, as it captures the organism when it is present in the circulating bloodstream. Other specimens—urine, CSF, or nasopharyngeal material—tend to yield the organism less reliably or only in specific, less consistent clinical scenarios. While bone marrow can have a higher yield, it requires an invasive procedure and is not routinely preferred. Therefore, blood is the optimal specimen for isolating the etiologic agent in suspected brucellosis.