CORYNEBACTERIUM

54 plus species including:

SPECIES

Corynebacterium accolans
Corynebacterium afermentans
Corynebacterium ammoniagenes
Corynebacterium amycolatum
Corynebacterium aquaticum
Corynebacterium asperum
Corynebacterium bovis
Corynebacterium callunae
Corynebacterium cystitidis
Corynebacterium diphtheriae
Corynebacterium flavescens
Corynebacterium genitalium
Corynebacterium jeikeium
Corynebacterium kutscheri
Corynebacterium matruchotii
Corynebacterium minutissimum
Corynebacterium mycetoides
Corynebacterium pilosum
Corynebacterium propinquum
Corynebacterium pseudodiphtheriticum
Corynebacterium pseudogenitalium
Corynebacterium pseudotuberculosis
Corynebacterium renale
Corynebacterium striatum
Corynebacterium ulcerans
Corynebacterium urealyticum
Corynebacterium vitaeruminis
Corynebacterium xerosis

Separate species, pathogenic to plants, exist.

MICROSCOPIC APPEARANCE

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.
Capsules: No.
Spores: No.
Other: Metachromatic granules of polymetaphosphate are commonly formed within the cells.

MACROSCOPIC APPEARANCE

Corynebacterium spp. usually appear as opaque, white or gray colonies. They may resemble non-hemolytic or alpha-hemolytic streptococci and commensal Neisseria spp.

METABOLIC PROPERTIES

Facultatively anaerobic. Chemoorganoheterotrophic having both a respiratory and fermentative type metabolism.

KEY BIOCHEMICAL REACTIONS

HABITAT

Primarily obligate parasites of mucous membranes or skin of mammals, but occasionally they are found in other sources. Some species are pathogenic to animals.

PATHOGENICITY

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.

RECOMMENDED MEDIA

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.).

INCUBATION

Temperature: 35 degrees C.
Time: 24-48 hours.
Atmosphere: Aerobic/Anaerobic.
Optimum pH: 7. 2 +/- 0.2.

REFERENCES

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.


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