Phylum Actinobacteria, Class Actinobacteria, Order Actinomycetales, Suborder Corynebacterineae, Family Mycobacteriaceae, Genus
Mycobacterium, Mycobacterium lacus Turenne et al. 2002.
Species description is based on a single strain.
Acid-fast, large bacilli with prominent beading. Does not form aerial hyphae or spores.
Colonies on Lowenstein-Jensen medium are small, dry, and non-chromogenic.
Colonies on Middlebrook 7H10 agar are small, non-pigmented, and smooth to rough
with a slightly irregular edge. Younger colonies appear slightly transparent. Visible
growth appears in 2 weeks at 37-42 ºC from dilute inocula, but requires 3-4 weeks at
25-30 ºC. Temperature range for growth is 25-42 ºC (optimum 37 ºC). Does not grow
on media supplemented with 5% (w/v) NaCl or on MacConkey agar (without crystal
Isolated from synovial tissue of a 68-year-old female patient with bursitis of the right elbow thought to be due to trauma whilst
swimming in a lake.
Susceptible (MIC) to amikacin (0.1 µg/ml), capreomycin (5.0 µg/ml), clarithromycin (2.0 µg/ml), ciprofloxacin (2.0 µg/ml), ethambutol
(2.0 µg/ml), ethionamide (2.5 µg/ml), isoniazid (0.1 µg/ml), kanamycin (2.5 µg/ml), levofloxacin (0.5 µg/ml), ofloxacin (1.0 µg/ml),
rifabutin (0.12 µg/ml), rifampin (0.5 µg/ml), Variable resistance to streptomycin (8 μg/ml).
- 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.
- Turenne C, Chedore P, Wolfe J, Jamieson F, Broukhanski G, May K, Kabani A. Mycobacterium lacus sp. nov., a novel slowly
growing, non-chromogenic clinical isolate. Int J Syst Evol Microbiol 2002; 52:2135-2140.
Positive results for acid phosphatase (weak reaction), arylsulfatase (weak reaction at 3 and 14 days), nitrate reduction, pyrazinamidase
(4 and 7 days), tellurite reduction, Tween 80 hydrolysis (weak reaction), and urease.
Negative results for acetamidase, nicotinamidase, succinamidase, heat-stable catalase (68 ºC), semiquantitative catalase test, iron
uptake, and niacin accumulation.
(c) Costin Stoica