Figure 1 is a culture of Mycobacterium phleigrowing in a slant of Lowenstein-Jensen agar. Two- to four-day-old cultures of this organism are good examples of a rapidly growing pigmented Mycobacterium sp. The colonies have a classic bread-crumb appearance.
Figure 2 is an acid-fast stain of M. phlei pure culture taken from a Lowenstein-Jensen agar slant. Two- to 3-day-old cultures make good specimens for acid-fast staining. This image was obtained with a bright-field microscope at a magnification of ´1,000. This image would help students visualize the morphology and color reaction of a mycobacterial species following acid-fast staining.
M. phleican sometimes be found on grass and hay. It has not thus far been shown to cause infection in humans, grows quite rapidly (1 to 2 days at 37oC), and would make a good specimen for use in identification of a mycobacterial unknown.