Description

• Gram-positive, nonmotile and acid-fast rods (3-7 µm long). Frequently join to grow in long threads.

• Rough, and nonphotochromogenic colonies.

• Rapid growth on egg media at 22-45°C, not at 52°C, in less than 5 days.
• Niacin negative, catalase positive, β-galactosidase usually positive.
• Tween 80 not hydrolysed after 14 days.
• Resistant to 5% NaCl, p-nitrobenzoic acid (0.5 mg/ml) and thiophene-2-carboxylic acid hydrazide (1 mg/l).