Phylum Firmicutes, Class Clostridia, Order Clostridiales, Family Clostridiaceae, Genus Clostridium, Cluster XIVa (Clostridium non
sensu stricto), Clostridium indolis McClung and McCoy 1957.
Historical synonym: Terminosporus indologenes Bezjak 1952
Gram-positive, straight to slightly curved rods, 0.5-0.9 x 1.3-10.2 µm, occuring singly
or in pairs. Motile by peritrichous flagella. Spores are round to oval, swollen, terminal
or subterminal; sporulation occurs most readily on chopped meat slants incubated at
Surface colonies on blood agar plates are nonhemolytic, 0.5–3.0 mm in diameter,
circular to slightly irregular, convex, translucent to opaque, white, with a dull, granular
surface and an entire to erose margin. Optimum temperature for growth is 37 ºC.
Weak and variable growth at 25 and 45 ºC. Optimum pH 7.6. Cultures in PYG broth
are turbid with a smooth sediment and have a pH of 5.3–5.7 after incubation for 3
days. Growth is stimulated by fermentable carbohydrates. Growth is inhibited by 20%
bile or 6.5% NaCl. Abundant gas is detected in PYG deep agar cultures. Products in
PYG broth include acetic acid; abundant H2 is detected. No aero-tolerance.
Isolated from soil, human feces, and human clinical specimens from infections associated with the intestinal tract.
Culture supernatant fluids are nontoxic to mice.
Isolated from human clinical specimens from infections associated with the intestinal tract.
- N.A. Logan and P. De Vos, 2009. Genus I. Clostridium Prazmowski 1880. In: (Eds.) P.D. Vos, G. Garrity, D. Jones, N.R. Krieg, W.
Ludwig, F.A. Rainey, K.-H. Schleifer, W.B. Whitman. Bergey’s Manual of Systematic Bacteriology, Volume 3: The Firmicutes,
- Smith L.D.S. and Hobbs G., 1974. Genus III. Clostridium Prazmowski 1880. In: (Eds.) Buchanan R.E. and Gibbons N.E., Bergey’s
Manual of Determinative Bacteriology, Eighth Edition, The Williams & Wilkins Company, Baltimore, 551-572.
Milk reaction is weak.
Positive results for H2 production, ammonia production, H2S production, indole production, neutral red reduction, nitrate reduction,
resazurin reduction, substrate utilization and/or acid production from: cellobiose, esculin, fructose, galactose, glucose, lactose,
maltose, raffinose, salicin, sucrose, trehalose & xylose.
Negative results for citrate utilization, lecithinase, substrate utilization and/or acid production from: adonitol, cellulose, dulcitol,
erythritol, glycogen, glycerol, inositol, inulin, melibiose, sorbitol, sorbose & starch.
Variable results for Voges-Proskauer test, substrate utilization and/or acid production from: amygdalin, arabinose, mannitol,
mannose, melezitose, rhamnose & ribose.
(c) Costin Stoica