Medically Important Mycobacteria Clinical Microbiology Review 212
ORGANISM PATHOGENICITY KEY POINTS
M. tuberculosis
M. bovis
M. africanum
M. avium complex (MAC)
M. hemophilum
M. ulcerans
Slow growth. Average recovery time by conventional
methods 21 days. Rough, dry, buff-colored (no pigmen-
tation) colonies. Serpentine cording on smear from
culture. Niacin & nitrate pos. 68°C catalase neg.
Rare in U.S. Bacille Calmette-Guérin (BCG) is attenuated
strain used in vaccine in some parts of world. Causes
false-pos PPD test.
Spread by respiratory droplets. Endemic in equatorial
Africa. Rare in U.S.
M. avium & M. intracellulare. Usually not differentiated.
Contracted from environment. Nonphotochromogens.
Requires hemin for growth. Grows best at 30°C.
Nonphotochromogen.
Endemic in tropics. 3rd most common mycobacterial
disease after TB & leprosy. Grows best at 30°C.
Nonphotochromogen.
Tuberculosis
GI infection following consumption of unpasteur-
ized milk
Causes lung infection. Disseminated disease in
immunocompromised
Most common NTM to cause lung disease in U.S.
Most common systemic bacterial infection in AIDS
patients. Cervical lymphadenitis in children
Skin, joint, bone, lung infections in immunocom-
promised. Lymphadenitis in children
Chronic infection of skin & subcutaneous tissue.
Buruli ulcers
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