54 plus species including:
Separate species, pathogenic to plants, exist.
|Gram Stain:||Positive. Some cells stain unevenly, giving a beaded appearance.|
|Morphology:||Pleomorphic coryneform rods. They may be straight or slightly curved with tapered and sometimes clubbed ends. One species ( Corynebacterium matruchotii ) has a "whip-handle" shape. Cells are usually arranged singly or in pairs, often in a "V" formation or in palisades of several parallel cells.|
|Size:||0.3-0.6 micrometers by 1.5-8.0 micrometers in length.|
|Motility:||They are non-motile and not acid-fast.|
|Other:||Metachromatic granules of polymetaphosphate are commonly formed within the cells.|
Corynebacterium spp. usually appear as opaque, white or gray colonies. They may resemble non-hemolytic or alpha-hemolytic streptococci and commensal Neisseria spp.
Facultatively anaerobic. Chemoorganoheterotrophic having both a respiratory and fermentative type metabolism.
KEY BIOCHEMICAL REACTIONS
- Most produce acid from glucose.
Primarily obligate parasites of mucous membranes or skin of mammals, but occasionally they are found in other sources. Some species are pathogenic to animals.
These organisms are found throughout nature, acting as pathogens and parasites of plants and animals. Although most species are harmless saprophytes and many are part of the normal human skin and mucous membrane flora, Corynebacterium diphtheriae , the agent of diphtheria, and Corynebacterium jeikeium and Corynebacterium urealyticum have been identified as causative agents of infections in compromised human hosts. Although non-diphtheria Corynebacterium have lower potential for human pathogenicity, they have been found to be a etiological agent of human endocarditis, meningitis, pneumonia, pharyngitis, osteomyelitis and bacteremia.
|For culture:||Blood Agar, Loefflers Medium, or Cooked Meat Medium.|
|For selective isolation:||Columbia CNA ( Corynebacterium spp.), Tinsdale Medium, or Cystine-Tellurite Agar ( Corynebacterium diphtheriae ).|
|For maintenance:||Cooked Meat Medium or CryoBeads™ (-70 degrees C.).|
|Temperature:||35 degrees C.|
|Optimum pH:||7. 2 +/- 0.2.|
1. Forbes, B.A., et al. 1998. Bailey and Scott's Diagnostic Microbiology , 10th ed. C.V. Mosby Company, St. Louis, MO.
2. Holt, J.G., et al. 1994. Bergey's Manual of Determinative Bacteriology , 9th ed. Williams & Wilkins, Baltimore, MD.
3. Holt, J.G., et al. 1986. Bergey's Manual of Systemic Bacteriology , Vol. I & II. Williams & Wilkins, Baltimore, MD.
4. The Oxoid Vade-Mecum of Microbiology . 1993. Unipath Ltd., Basingstoke, UK.
5. Internet: www.hardlink.com /Bacterial Database Search, February, 1998.
6. Murray, P.R., et al. 1995. Manual of Clinical Microbiology , 6th ed. American Society for Microbiology, Washington, D.C.