Taxonomy
Morphology
Cultural characteristics
Biochemical characters
Ecology
Pathogenicity
References
Phylum Firmicutes, Class Clostridia, Order Clostridiales, Family Clostridiaceae, Genus Clostridium, Cluster I (Clostridium sensu
stricto
), Clostridium septicum  (Mace 1889) Ford 1927.
Historical synonyms:
Bacillus septicus  Mace 1889, Vibrio septicus  Rottgardt 1926.
Gram-positive (Gram-negative in older cultures) straight or curved rods, 0.6-1.9 x
1.9-35.0 µm, occuring singly or in pairs.
Forms filaments on the peritoneal surface of
the liver of infected animals. Cells may be extremely pleomorphic under certain
conditions. Motility is variable. Spores are oval, subterminal, swelling the cell
.
Cell wall is susceptible to dissolution by lysozyme.
Surface colonies on blood agar plates are 1-5 mm in diameter, beta-hemolytic, slightly
raised, translucent, gray, glossy, circular, with irregular to rhizoid margins, often
swarming. Subsurface colonies in 1% agar are spherical or lenticular and transparent;
in 2% agar, Colonies are brownish-yellow and heart shaped. Cultures in PYG broth are
turbid with a smooth sediment and have a pH of 4.7
-5.3  after incubation for 5 days.
Moderate  growth in nutrient broth or cooked meat broth.
Growth is inhibited by 6.5% NaCl, 20% bile, or a pH of 8.5. Grows at: 44 ºC, optimum at 37-40 ºC. Growth at 46 ºC is negative.
Growth is stimulated by fermentable carbohydrate, serum or peptic digest of blood. Products in PYG (peptone, yeast extract, glucose)
broth:  acetic and butyric  acids, formic acid and H
2. CO2 is not required for growth, but good growth occurs in atmospheres containing
up to 100% CO
2. Approximately 50% of cells of Clostridium septicum survive to to hyperbaric oxygen (100% O2 at 3 atm.). No aerobic
growth on blood-agar. Essential factors for growth include biotin, nicotinic acid, pyridoxine, thiamin, cysteine, tryptophan, iron and, for
some strains, pantothenate. Abundant gas is produced in PYG deep agar cultures.
Isolated from soil, probably the gastrointestinal tract content of many domesticated animals, rattlesnake venom, feces of human
infants and adults, animal infections including wound infections, myositis and enterotoxemia in ruminants and bacteremia, human
infections including bacteremia, suppurative infections, necrotizing enterocolitis, and myonecrosis or gas gangrene.
Susceptible to chloramphenicol, clindamycin, erythromycin, penicillin G, and tetracycline.
Bacteriocin produced by
Clostridium septicum inhibited RNA and protein synthesis, and rapidly kills C. septicum and C.chauvoei.
Pathogenic for laboratory animals (mice, guinea pigs).
Produce deoxyribonuclease (beta toxin) , hyaluronidase (gamma toxin), an oxygen-stable hemolysin with necrotizing properties (alpha
toxin),  an oxygen-labile hemolysin (delta toxin), a neuraminidase, a hemagglutinin and a chitinase.
Is capable of causing rapidly fatal infections in humans and other animals by production of its lethal hemolytic and necrotizing alpha
toxin. In cattle, wound infection produces “malignant oedema” and in sheep, braxy, a fatal bacteremic infection following penetration of
the abomasal wall. Similar diseases have been noted in other species of domestic and wild animals.
C. septicum, C. perfringens, and C. novyi are the three most common causes of clostridial myonecrosis (gas gangrene).
  1. 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,
    Springer, 738-828.
  2. Smith L.D.S. and Hobbs G., 1975. 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.
  3. Macovei A., 2009. Identificarea bacteriilor anaerobe. In: Tratat de Microbiologie Clinica (Ed. Buiuc D. si Negut M.), editia a IIIa,
    Editura Medicala, Bucuresti, 900-927.
  4. Secasiu V., 2001. Boli produse de germeni din genul Clostridium. In: Boli infectioase ale animalelor, Moga Manzat R., Ed. Brumar,
    Timisoara, 481-612.
H2 is produced very abundantly. Milk reaction: curd. Meat digestion is negative. Clostridium chauvoei can be differentiated from
Clostridium septicum, which it resembles most closely phenotypically, by its fermentation of sucrose and lack of fermentation of
cellobiose or trehalose.

Positive results for H
2 production, DN-ase, esculin hydrolysis, gelatin hydrolysis, neuraminidase, neutral red reduction, resazurin
reduction, substrate utilized and/or acid produced from: cellobiose (weak), fructose, galactose (weak), glucose, lactose, maltose,
mannose & trehalose (weak).
Negative results for casein hydrolysis, H
2S production, indole production, lecithinase, lipase, starch hydrolysis, urease,
Voges-Proskauer reaction, substrate utilized and/or acid produced from: amygdalin, adonitol, arabinose, dulcitol, erythritol, glycogen,
glycerol, inositol, inulin, mannitol, melezitose, melibiose, raffinose, rhamnose, sorbitol, starch, sucrose & xylose.

Variable results for nitrate reduction, hydrolysis of hippurate, substrate utilized and/or acid produced from: ribose, salicin & sorbose.
Clostridium septicum
(c) Costin Stoica
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