B4.5 NONTUBERCULOUS MYCOBACTERIA Flashcards
What are other names for Nontuberculous Mycobacteria (NTM)?
Atypical Mycobacteria,
Mycobacteria Other Than Tubercle Bacillus (MOTT),
Anonymous,
Unclassified,
Unknown,
Tuberculoid,
Environmental, or
Opportunistic.
Where are NTMs commonly found, and how do they infect individuals?
Found in the environment.
Can colonize the skin, respiratory tract, and gastrointestinal tract of healthy individuals
What is the typical clinical presentation of NTM infections?
Chronic pulmonary disease resembling TB.
Are NTMs transmissible from person to person?
No, NTMs are non-transmissible between individuals.
How are NTMs classified in the Runyon system
By growth rate and colonial pigmentation into four groups.
What are the two growth rates used in the Runyon classification?
Slow growers.
Rapid growers.
They produce pigment when exposed to light.
in the Runyon classification
photochromogens
PHOTOCHROMOGEN SPP
Mycobacterium kansasii
Mycobacterium marinum
known as the Yellow Bacillus
Mycobacterium kansasii
Produces yellow pigment with prolonged light exposure
Mycobacterium kansasii
What is the clinical significance of M. kansasii?
Pulmonary: Chronic cavitary lesions.
Extrapulmonary: Lymphadenitis, skin, soft tissue, and joint infections.
Cultural characteristics of M. kansasii colonies?
Grows on Middlebrook 7H10 agar.
Colonies are slow-growing, smooth to rough, with wavy edges and dark centers.
Prolonged light exposure: Dark red β-carotene crystals on colony surfaces.
Biochemical test results for M. kansasii?
Catalase: Strongly positive (>45 mm in semiquantitative test).
Tween 80 hydrolysis: Positive (3 days).
Nitrate reduction: Positive.
Niacin: Negative.
Pyrazinamidase production: Positive.
Microscopic appearance of M. kansasii?
Long rods with distinct crossbanding.
What is the environmental association and clinical presentation of M. marinum?
Environment: Found in fish and aquariums.
Disease: Swimming pool granuloma, tender red or blue-red subcutaneous nodules on elbows, knees, toes, or fingers.
Optimal growth temperature and culture characteristics for M. marinum?
Grows best at 28–32°C.
Egg-based medium: Smooth to rough and wrinkled.
Middlebrook 7H10/7H11 agar: Smooth colonies
Biochemical test results for M. marinum?
Tween 80 hydrolysis: Positive.
Weakly catalase: Positive.
Niacin: Negative.
Urease: Positive.
Pyrazinamidase: Positive
Drug susceptibility and resistance of M. marinum?
Susceptible: Rifampin and ethambutol.
Resistant: Isoniazid and pyrazinamide.
Intermediate: Streptomycin.
Microscopic appearance of M. marinum?
Moderately long to long rods with crossbarring.
They produce yellow to orange pigment regardless of light exposure.
Scotochromogens
What disease is primarily associated with M. scrofulaceum?
Cervical lymphadenitis in children
Cultural characteristics of M. scrofulaceum
Slow-grower (4–6 weeks).
Grows at 25–37°C.
Smooth colonies with dense centers, light yellow to orange pigment
Microscopic appearance of M. scrofulaceum?
Uniformly stained, acid-fast, medium to long rods.
Biochemical test results for M. scrofulaceum
Tween 80 hydrolysis: Negative.
Urease: Positive.
Catalase: Positive (>45 mm).