Which test would you order to screen for bloodstream infection?

• A. Sodium
• B. Blood Cultures
• C. Creatinine
• D. Glucose

Answer: (B)

Detecting a bloodstream infection relies on directly identifying viable organisms in the blood, which is accomplished by blood cultures. By drawing blood and placing it in culture media, any bacteria or fungi present can grow, allowing you to identify the organism and, if needed, perform antibiotic susceptibility testing. This makes blood cultures the most informative test for bacteremia or sepsis, because they provide direct evidence of infection in the bloodstream.

The other tests measure different things. Sodium checks electrolyte balance, creatinine assesses kidney function, and glucose screens blood sugar. While these labs can be affected by infection or sepsis, they do not detect organisms in the blood and thus are not used to screen for bloodstream infection.