Gram‐ghost bacilli

: A 76-year-old man presented with a 3-day history of a productive cough and right chest pain on inspiration. The Gram stain of the sputum showed unstained bacilli and polynuclear leukocytes, suggesting a diagnosis of pulmonary acid-fast bacillus infection. Mycobacteria can be identified by Gram staining and are reported to be Gram-neutral or Gram-ghost, and recognition of Gram-ghost bacilli in the initial specimen may assist in distinguishing mycobacterial infection from community-acquired pneumonia.