Which test is gold standard for culture of the lower airway disease?

• A. BAL
• B. TBA
• C. CT
• D. Ultrasound

Answer: (B)

Obtaining a culture from the lower airways requires a sample that truly represents the distal lung tissue where lower airway disease occurs. Bronchoalveolar lavage does this by directing sterile saline into a specific bronchial segment and then collecting the fluid back. The returned sample pulls organisms and inflammatory cells from the alveolar spaces, giving a true reflection of lower airway microbiology and cytology. This approach has the highest diagnostic yield for infections and inflammatory conditions of the lower airways and minimizes contamination from the upper airways compared with samples taken from the trachea or mouth. Imaging tests like CT or ultrasound can show structure and guide procedures, but they do not produce culture material. While other sampling methods exist, bronchoalveolar lavage remains the gold standard for culture of the lower airway.