RUNYON CLASSIFICATION

Runyon classification

Slowly growing Mycobacteria	Runyon IV: Rapid Growers
Runyon I: Photochromogens produce a yellow-orange pigment when exposed to light §  Mycobacterium kansasii,  §  Mycobacterium marinum,  §  Mycobacterium simiae Mycobacterium asiaticum §	colonies in 5 days do not produce pigment.  §  Mycobacterium fortuitum,  §  Mycobacterium chelonae,  §  Mycobacterium peregrinum,  §  Mycobacterium abscessus, §  Mycobacterium thermoresistible Some rapidly growing mycobacteria are considered "late-pigmenting"
Runyon II: Scotochromogens produce a yellow-orange pigment in light or in the dark. Some become darker with exposure to light §  Mycobacterium scrofulaceum, §  Mycobacterium gordonae,  §  Mycobacterium szulgai,  §  Mycobacterium xenopi,  §  Mycobacterium celatum,  §  Mycobacterium flavescens
Runyon III: Nonchromogenic do not produce pigment some may produce very pale yellow, buff, or tan pigment but do not intensify upon light exposure §  Mycobacterium avium-intracellulare,  §  Mycobacterium paratuberculosis,  §  Mycobacterium terrae,  §  Mycobacterium shimoidae,  §  Mycobacterium genavense