A 65-year-old female was referred to pulmonology for evaluation of a chronic cough and shortness of breath. Chest imaging showed several tree-in-bud nodules in the lungs, which led to bronchoscopy with the collection of 3 lower respiratory samples.
Samples were sent to the clinical microbiology laboratory for bacterial, fungal and mycobacterial stains and cultures. The Gram stains showed abundant polymorphonuclear leukocytes with rare mixed bacterial flora and showed no squamous epithelial cells.
The mycology and mycobacteriology direct specimen stains were negative. The bacterial cultures grew normal upper respiratory flora. The mycology cultures remained no growth. On day 7, 2 of the mycobacterial liquid cultures flagged positive. On day 8, the third mycobacterial liquid culture flagged positive.
A Kinyoun acid-fast stain confirmed presence of mycobacteria in all 3 samples. A rapid molecular test identified a target of concern in 2 of 3 specimens. Within 2.5 weeks, colony growth on the solid agar was identified by MALDI-TOF mass spectrometry as something different than the molecular results. By the fourth week, there were multiple colony morphologies observed on the Lowenstein-Jensen (LJ) slant.
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Allison Eberly, Ph.D., D(ABMM), Washington University in Saint Louis School of Medicine
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