ch.18 aerobic actinomytes (Mycobacterium, streptomyces)

Niacin-positive
Nitrate-postive
Takes 3 weeks to grow
resistant to T2H

-Niacin is the precursor to the synthesis of NAD, all mycobacterium produce niacin, but some produce excess that is excreted from the cell. The niacin accumulates in the medium and can be detected by reacting with cyanogen halide

reduces nitrate to nitrite

photochromogen (produces pigment after exposure to light only)

scotochromogen (produces pigment in dark or in the light)

Nonphotochromogens

rapid growers

Mycobacterium sp.

cau be used to make a presumptive ID of M.tuberculosis, M. avium-intracellulare and other species

the NAP test is performed in a BACTEC bottle & provides a rapid method to distinguish M.tuberculosis and M. bovis (growth is inhibited) from other mycobacterium spp. (growth is not inhibited)

This is used for the isolation of Mycobacterium & other acid-fast bacteria. Egg supplement enhances the growth of Mycobacterium and malachite green prevents growth of the majority of contaminants.

produces heat-liable catalase

the enzyme catalase converts hydrogen peroxide into water and oxygen, the latter of which can be seen as visible bubbles

are nonphotochromogenic (Group III)

the ability of Mycobacterium spp. to produce a yellow or orange pigment and whether pigment production require light is used as a mycobacterial id characteristic

Causes disseminated, non-TB disease in AIDS; often resistant to multiple drugs. Prophylaxis with azithromycin when CD4+ count < 50 cells/mm^3

niacin negative
nitrate negatigve
T2H-resistant
NAP-resistant
heat-stable catalase