Phylum Firmicutes, Class Clostridia, Order Clostridiales, Family Clostridiaceae, Genus Clostridium, Cluster XVIII (Clostridium non
sensu stricto), Clostridium ramosum (Veillon and Zuber 1898) Holdeman, Cato and Moore 1971.
Historical synonyms: Bacillus ramosus Veillon and Zuber 1898, Nocardia ramose
Vuillemin 1931, Ramibacterium ramosum (Veillon and Zuber 1898) Prevot 1938.
Gram-positive/negative straight rods , 0.5-0.9 x 2.0-12.8 µm, occuring singly, in pairs
or in short chains, often in “V” arrangements, with a “rail fence” appearance, or in
irregular masses. Cells may have central or terminal swellings up to 1.6 μm in width.
Non-motile. Spores are round/oval, usually terminal, and swell the cell; spores are
very rarely seen and often are difficult to detect by heat tests. They can be
demonstrated most readily from 3-week-old chopped-meat agar slants incubated at
30 ºC, or in old chopped meat or PYG broth cultures.
Surface colonies on blood agar plates are 0.5–2 mm in diameter, circular to slightly
irregular, convex or raised, colorless to gray-white, translucent or semiopaque, and
smooth, with an entire, scalloped, or erose margin, and a mottled, mosaic, or granular
internal structure. Nonhemolytic. No aero-tolerance. Cultures in PYG broth are turbid with a smooth or ropy sediment and have a pH of
4.4–4.8 after incubation for 5 days. Growth is stimulated by fermentable carbohydrates. Growth is inhibited by 6.5% NaCl and
reduced in 20% bile. Optimum temperature for growth is 37 ºC. Can grow at 20 and 45 ºC. Products in PYG broth are acetic, lactic
and formic acids. Moderate gas is detected in glucose deep agar cultures.
Isolated from infant and adult feces; normal human cervix; human infections of the abdominal cavity, genital tract, lung, biliary tract,
blood cultures. Susceptible to chloramphenicol.
Culture supernatants are not toxic to mice, but strains are pathogenic for guinea pigs; pathogenicity may be lost in laboratory cultures.
Toxin is not produced.
Isolated from human clinical samples.
- 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 positive (curd production). Meat is not digested.
Positive results for esculin hydrolysis, substrate utilization and/or acid production from amygdalin, cellobiose, esculin, fructose,
galactose, glucose, lactose, maltose, mannose, raffinose, salicin, sucrose & trehalose.
Negative results for casein hydrolysis, gelatin hydrolysis, H2S production, indole production, lecithinase, lipase, nitrate reduction,
starch hydrolysis, urease, substrate utilization and/or acid production from: adonitol, cellulose, erythritol, glycogen, glycerol, inositol,
inulin, melezitose, sorbitol & sorbose.
Variable results for hydrogen production, ammonia production, hydrogen production, Voges-Proskauer reaction, substrate utilization
and/or acid production from: arabinose, dulcitol, mannitol, melibiose, rhamnose, ribose, starch & xylose.
(c) Costin Stoica