17 out of 22
A 60-year-old man with a chronic cough, bloody sputum, and marked weight loss is diagnosed as having tuberculosis. A "serpentine-like" colonial morphology is noted on Lowenstein-Jensen agar. This latter finding is caused by which of the following factors?
|A||A large "slimy" capsule|
Ans. D Cord factor
Virulent strains of M. tuberculosis grow in a characteristic "serpentine" cordlike pattern, whereas avirulent strains do not. Virulence of the organism is correlated with cord factor (trehalose dimycolate).