For a patient with suspected sepsis or severe infection, which diagnostic test should be obtained first?

For a patient with suspected sepsis or severe infection, which diagnostic test should be obtained first?

• A. MRI of the brain
• B. Urine culture
• C. Blood culture
• D. Chest X-ray

Answer: (C)

When sepsis is suspected, obtaining blood cultures first is essential because they confirm bacteremia and guide antibiotic therapy. Drawing blood cultures before starting antibiotics maximizes the chance of identifying the causative organism and its susceptibilities, especially when multiple sites are sampled to improve yield and distinguish true infection from contamination. While imaging or other cultures help locate a source, they don’t provide the critical confirmation of bloodstream infection as quickly. A chest X-ray may reveal a pulmonary source, and a urine culture is helpful if a urinary source is suspected, but neither replaces the need to confirm bacteremia. If the patient is unstable, start broad-spectrum antibiotics promptly after cultures are drawn to avoid delaying treatment.

When sepsis is suspected, obtaining blood cultures first is essential because they confirm bacteremia and guide antibiotic therapy. Drawing blood cultures before starting antibiotics maximizes the chance of identifying the causative organism and its susceptibilities, especially when multiple sites are sampled to improve yield and distinguish true infection from contamination. While imaging or other cultures help locate a source, they don’t provide the critical confirmation of bloodstream infection as quickly. A chest X-ray may reveal a pulmonary source, and a urine culture is helpful if a urinary source is suspected, but neither replaces the need to confirm bacteremia. If the patient is unstable, start broad-spectrum antibiotics promptly after cultures are drawn to avoid delaying treatment.