When airborne isolation is ordered for suspected TB, what is the recommended specimen collection practice?

• A. A sputum specimen should be collected for acid-fast bacilli (AFB) three times each day if TB is suspected
• B. Collect blood cultures daily
• C. Collect sputum only once
• D. Place the patient in standard precautions

Answer: (A)

The key idea is that confirming TB relies on detecting the bacteria in respiratory secretions, and doing this with multiple samples increases diagnostic yield. Sputum collected for acid-fast bacilli testing may be intermittently positive, and the sensitivity of a single specimen isn’t reliable. By obtaining three sputum specimens for AFB smear and culture, you maximize the chance of catching bacilli if they’re present, which helps you quickly determine whether airborne precautions can be safely de-escalated and when to start treatment. Blood cultures don’t diagnose TB and aren’t helpful here, collecting sputum only once misses cases, and standard precautions alone don’t provide the necessary protection for a patient under airborne isolation.