Actinobacillus capsulatus
Taxonomy
Morphology
Cultural characteristics
Biochemical characters
Ecology
Pathogenicity
References
Phylum Proteobacteria, Class Gammaproteobacteria, Order Pasteurellales, Family Pasteurellaceae, Genus Actinobacillus,
Actinobacillus capsulatus
Arseculeratne 1962.
Gram-negative, rod-shaped cells  0.6-1,2 µm; filamentous bacilli that fragment into minute and coccoid bodies are seen in old cultures.
Capsules are present. Nonmotile. Nonsporulated.
Primary cultures will not grow on nutrient agar or in nutrient broth but subcultures
grow as pinpoint colonies or as a faint turbidity. Colonies on sheep blood agar are
very sticky and “flower head” colonies are produced on rabbit blood agar. Small
discrete mural colonies occur in serum broth.
No hemolysis on sheep blood agar (slight hemolysis may  appear after 48 hours).
Weakly CAMP positive using bovine blood.
Aerobic, facultatively anaerobic. Growth favored on primary isolation only by the
addition of 10% CO
2. Optimum temperature 37 ºC. No growth at 22 ºC.
Growth on MacConkey agar is variable.  V-factor independent.
Isolated from rabbits, kitten and hare.
Cause of various pathological lesions in rabbits, septicaemia in a kitten and conjunctivitis of a hare.
  1. Olsen I., Moller K., 2004. Genus II. Actinobacillus. In: Bergey’s Manual of Systematic Bacteriology, Second edition, Vol two, part B,
    George M. Garrity (Editor-in-Chief), pp. 866-883.
  2. W.M. Janda, R. Mutters, 2006. Pasteurella, Mannheimia, Actinobacillus, Eikenella, Kingella, Capnocytophaga, and other
    miscellaneous Gram-negative rods. In: Topley & Wilson’s Microbiology and Microbial Infections, 10 edition, Vol. 2, Bacteriology,
    Edward Arnold Ltd.
  3. J. G. Holt et al., 1994. Facultatively Anaerobic Gram-Negative Rods. Subgroup 3. Family Pasteurellaceae. In: Begey’s Manual of
    Determinative Bacteriology, 9th-edition, Williams & Wilkins, pp 194-196.
  4. Buchanan R.E., Gibbons N.E. (co-editors), 1975. Bergey’s  Manual of Determinative Bacteriology, eight edition, The Williams &
    Wilkins Company, Baltimore.
  5. Kuhnert P. , Korczak B. M., Christensen H. and Bisgaard M., 2007. Emended description of Actinobacillus capsulatus
    Arseculeratne 1962, 38AL. IJSEM,57,625-632.
  6. Bisgaard M, Christensen H. Classification of avian haemolytic Actinobacillus-like organisms (Bisgaard taxon 26) associated with
    anseriforme birds as Actinobacillus anseriformium sp. nov. Int J Syst Evol Microbiol 2012; 62:352-358.
Positive results for nitrates reduction, oxidase, alkaline phosphatase, catalase, urease,
alpha-glucosidase, ONPG, acid production from: D(+) xylose, mannitol, D(-) sorbitol,
D(-) fructose, D(+) galactose, D(+) glucose (without gas production), D(+) mannose, lactose, glycerol, maltose, melibiose (delayed),
sucrose, raffinose, trehalose, esculin, salicin
and dextrin.

Negative results for gelatinase, H
2S production, Voges-Proskauer reaction, arginine dehydrolase, lysine decarboxylase, ornithine
decarboxylase, indole production, acid production from: D(-) arabinose, dulcitol, meso-inositol, L(+) rhamnose, L(-) sorbose,
cellobiose, inulin
and fucose.
(c) Costin Stoica
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