Which specimen is best for culture when a catheter-associated infection is suspected after catheter removal?

• A. Catheter tip
• B. Blood culture from peripheral line
• C. Urine culture
• D. Stool culture

Answer: (A)

When a catheter-associated infection is suspected after removal, testing the catheter itself provides the most direct evidence of the source. Culturing the catheter tip (using the semiquantitative, roll-plate technique) can reveal bacterial colonization on the catheter. A significant colony count from the tip supports that the catheter was the source of infection, especially if it matches organisms found in the patient's blood cultures and there are compatible clinical signs. Peripheral blood cultures can confirm bacteremia but don’t prove the catheter caused the infection. Urine and stool cultures target other sites and would not establish catheter-related infection in this scenario.