<unk>  are rod-shaped bacteria. They appear purple ("Gram positive") under Gram stain and bright red ("acid fast") under Ziehl–Neelsen stain. On laboratory media,<unk>  grow slowly, forming small transparent colonies after four weeks. As colonies age, they develop irregular outlines and a rough, yellow surface.
Mycobacterium ulcerans
Mycobacterium leprae
Mycobacterium orygis
Mycoplasma incognitus
Mycobacterium lepromatosis
Mycobacterium africanum
Mycoplasma pirum
Mycoplasma orale