- Runyon classification
The Runyon classification of nontuberculous
mycobacteria based on the rate of growth, production of yellow pigment and whether this pigment was produced in the dark or only after exposure to light. On these bases, the nontuberculous mycobacteria are divided into four groups:1. Runyon I: PhotochromogensRunyon I organisms are slow growing, and produce a yellow-orange pigment when exposed to light.M. kansasii, M. marinum
2. Runyon II: ScotochromogensRunyon II organisms are slow growing, and produce a yellow-orange pigment in light or in the dark.M. scrofulaceum, M. gordonae, M. szulgai
3. Runyon III: NonchromogenicRunyon III organisms are slow growing, and do not produce pigment.M. avium-intracellulare, M. xenopi, M. terrae
4. Runyon IV: Rapid GrowersRunyon IV organisms are rapid growing for mycobacteria (colonies in 5 days). They do not produce pigment.M. fortuitum, M. peregrinum, M. abscessus, M. chelonae
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