What infection prevention measure is critical for immunocompromised patients regarding antibiotic prophylaxis timing?

• A. Within 30 minutes before incision.
• B. Within 60 minutes before incision.
• C. 24 hours post-op.
• D. Only if signs of infection appear.

Answer: (B)

The key idea is timing antibiotic prophylaxis so that tissue levels are high at the moment the incision is made, preventing bacteria introduced during surgery from establishing infection. In immunocompromised patients, achieving adequate tissue concentration at the start of incision is even more crucial because their defenses are reduced.

Administer the prophylactic antibiotic within 60 minutes before incision so peak tissue levels align with the incision. For antibiotics that require longer infusions, such as vancomycin, start within about 120 minutes before incision to finish the infusion by the time the incision begins.

Giving antibiotics too early can mean tissue levels drop by the time the incision is made, and starting after the incision won’t prevent the initial contamination. Prophylaxis after the operation or only if signs of infection appear does not prevent surgical site infections and can increase risks.