| Mycobacterium fallax |
Taxonomy
Morphology
Cultural characteristics
Biochemical characters
Ecology
Pathogenicity
References
Phylum Actinobacteria, Class Actinobacteria, Order Actinomycetales, Suborder Corynebacterineae, Family Mycobacteriaceae, Genus
Mycobacterium, Mycobacterium fallax Levy-Frebault et al. 1983.
Mycobacterium, Mycobacterium fallax Levy-Frebault et al. 1983.
Acid-fast short rods, 0.5 x 1.0 μm, except for a small number (less than 20%) of
cyanophil forms. Smears prepared from Youman’s medium (without Tween 80) show
clumps of rods or cords.
cyanophil forms. Smears prepared from Youman’s medium (without Tween 80) show
clumps of rods or cords.
Growth occurs within 5 days at 30 ºC on Lowenstein-Jensen, Middlebrook 7H10, and
nutrient agar media. Larger colonies are produced by incubation at 37 ºC, but
colonies grow more slowly (12-21 d or more); significant numbers of isolates fail to
grow on nutrient agar at this temperature. At both temperatures, colonies are eugonic,
rough, and buff-colored, and resemble those of Mycobacterium tuberculosis. Does
not grow at 42, 45 or 52 ºC. No growth on MacConkey agar w/o crystal violet or on
media supplemented with 5% NaCl.
nutrient agar media. Larger colonies are produced by incubation at 37 ºC, but
colonies grow more slowly (12-21 d or more); significant numbers of isolates fail to
grow on nutrient agar at this temperature. At both temperatures, colonies are eugonic,
rough, and buff-colored, and resemble those of Mycobacterium tuberculosis. Does
not grow at 42, 45 or 52 ºC. No growth on MacConkey agar w/o crystal violet or on
media supplemented with 5% NaCl.
Isolated from river and lake water, few from human sputum.
Susceptible to hydroxylamine (500 μg/ml), ethambutol (2 μg/ml), kanamycin (20 μg/ml), rifampin (40 μg/ml). Resistant to thiophene-2-
carboxylic acid hydrazide (2 μg/ml), ethionamide (20 μg/ml), isoniazid (0.1 μg/ml), and streptomycin (4 μg/ml).
Susceptible to hydroxylamine (500 μg/ml), ethambutol (2 μg/ml), kanamycin (20 μg/ml), rifampin (40 μg/ml). Resistant to thiophene-2-
carboxylic acid hydrazide (2 μg/ml), ethionamide (20 μg/ml), isoniazid (0.1 μg/ml), and streptomycin (4 μg/ml).
Considered to be non-pathogenic.
- John G. Magee and Alan C. Ward 2012. Family III. Mycobacteriaceae Chester 1897, 63AL in Bergey’s Manual of Systematic
Bacteriology, Volume Five The Actinobacteria, Part A, Michael Goodfellow & al. (editors), 312-375. - Levy-Frebault V, Rafidinarivo E, Promé JC, Grandry J, Boisvert H, David HL. Mycobacterium fallax sp. nov. Int. J. Syst. Bacteriol.
1983; 33:336-343. - Luquin M, Ausina V, Vincent-Levy-Frebault V, Laneelle MA, Belda F, Garcia-Barcelo M, Prats G, Daffe M. Mycobacterium brumae
sp. nov., a rapidly growing, nonphotochromogenic mycobacterium. Int. J. Syst. Bacteriol. 1993; 43:405-413. - Cecilia Brambilla, Alejandro Sanchez-Chardi, Mıriam Perez-Trujillo, Esther Julian and Marina Luquin 2012. Cyclopropanation of -
mycolic acids is not required for cording in Mycobacterium brumae and Mycobacterium fallax. Microbiology (Reading, England).
158. 1615-21. 10.1099/mic.0.057919-0. - Tsukamura M, Yano I, Imaeda T. Mycobacterium fortuitum subspecies acetamidolyticum, a new subspecies of Mycobacterium
fortuitum. Microbiol Immunol 1986; 30:97-110.
Positive results for alpha-esterase, nitrate reduction, catalase, Tween 80 hydrolysis (10 days).
Can utilize as sole carbon source aceteate, pyruvate, fructose and ethanol.
Negative results for acid phosphatase, arylsulfatase (3 days), heat-stable catalase (68 ºC), beta-glucosidase, beta-galactosidase,
iron uptake, niacin accumulation, acetamidase, benzamidase, isonicotinamidase, and urease.
No utilization of benzoate, citrate, malate, fumarate, mannitol, and inositol.
Variable results for nicotinamidase, and pyrazinamidase.
Can utilize as sole carbon source aceteate, pyruvate, fructose and ethanol.
Negative results for acid phosphatase, arylsulfatase (3 days), heat-stable catalase (68 ºC), beta-glucosidase, beta-galactosidase,
iron uptake, niacin accumulation, acetamidase, benzamidase, isonicotinamidase, and urease.
No utilization of benzoate, citrate, malate, fumarate, mannitol, and inositol.
Variable results for nicotinamidase, and pyrazinamidase.
(c) Costin Stoica
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