4.5 Flashcards
(90 cards)
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.
What are photochromogens?
They produce pigment when exposed to light.
What are the PHOTOCHROMOGEN species?
Mycobacterium kansasii, Mycobacterium marinum.
What is known as the Yellow Bacillus?
Mycobacterium kansasii.
What is the clinical significance of M. kansasii?
Pulmonary: Chronic cavitary lesions. Extrapulmonary: Lymphadenitis, skin, soft tissue, and joint infections.
What are the 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.
What are the 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.
What is the 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.
What is the 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.
What are the biochemical test results for M. marinum?
Tween 80 hydrolysis: Positive. Weakly catalase: Positive. Niacin: Negative. Urease: Positive. Pyrazinamidase: Positive.
What is the drug susceptibility and resistance of M. marinum?
Susceptible: Rifampin and ethambutol. Resistant: Isoniazid and pyrazinamide. Intermediate: Streptomycin.
What is the microscopic appearance of M. marinum?
Moderately long to long rods with crossbarring.
What are the characteristics of scotochromogens?
They produce yellow to orange pigment regardless of light exposure.
What disease is primarily associated with M. scrofulaceum?
Cervical lymphadenitis in children.
What are the 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.
What is the microscopic appearance of M. scrofulaceum?
Uniformly stained, acid-fast, medium to long rods.
What are the biochemical test results for M. scrofulaceum?
Tween 80 hydrolysis: Negative. Urease: Positive. Catalase: Positive (>45 mm).
What is the drug resistance of M. scrofulaceum?
Resistant to isoniazid, streptomycin, ethambutol, and p-aminosalicylic acid.