VIBRIO

43 plus species including:

SPECIES

MICROSCOPIC APPEARANCE

Gram Stain: Gram-positive.
Morphology: Curved or straight rods. Occasionally united into "S" shapes or spirals, typically sheathed and continuous with the outer membrane of the cell wall. Swarming often occurs.
Size: 0.5-0.8 micrometers by 1.4-2.6 micrometers.
Motility: Motile by one or more polar flagella.
Capsules: None.
Spores: None.

MACROSCOPIC APPEARANCE

Most species give rise to convex, smooth, and creamy white colonies with entire edges. Colonies grown on TCBS appear yellow/green; those grown on MacConkey Agar may appear colorless.

KEY BIOCHEMICAL REACTIONS

METABOLIC PROPERTIES

Facultatively anaerobic. Chemoorganotrophic, having both a fermentative and respiratory type metabolism. Glucose is fermented by the mixed acid fermentation, usually without gas. Sodium ions stimulate growth of all species and are an absolute requirement for most species.

HABITAT

Found in aquatic environments with a wide range of salinities (freshwater, estuarine, and marine). Saprophytic in salt and fresh water and soil. Subsequent studies have found that the Gulf Coasts of the North and South America were natural reservoirs for a unique strain of V . cholerae . (8)

PATHOGENICITY

Infections with V. cholerae may be asymptomatic, mild, or severe. If not treated, patients with severe cholera may die within hours as a result of massive fluid and electrolyte loss. V. cholerae is spread by the fecal-oral route.

Vibrio species may also contribute to food poisoning caused by contaminated fish or shellfish, and fatal septicemia. These and other species are associated with wound infections, diarrheal disease, and a variety of extraintestinal infections.

RECOMMENDED MEDIA

For culture: Nutrient Broth with NaCl or Blood Agar 5%.
For selective isolation: TCBS Medium, MacConkey Agar, and Alkaline-Peptone Medium for cold enrichment.
For maintenance: Nutrient Agar, Tryptic Soy Agar, Blood Agar 5% and many specialized media for Vibrio spp. may be Lyophilized for long-term preservation. (2)

INCUBATION



Temperature: (clinical samples)
(environmental samples)
35 degrees C.
20-30 degrees C.
Time: (clinical samples)
(environmental samples)
6-8 hours.
18-24 hours.
Atmosphere: Aerobic.
pH: Variable (e.g. Vibrio cholerae can grow at pH 10).

REFERENCES

1. Holt, J.G., et al. 1994. Bergey's Manual of Determinative Bacteriology , 9th ed. Williams & Wilkins, Baltimore, MD.

2. Holt, J.G., et al. 1986. Bergey's Manual of Systemic Bacteriology , Vol. I & II. Williams & Wilkins, Baltimore, MD.

3. The Oxoid Vade-Mecum of Microbiology . 1993. Unipath Ltd., Basingstoke, UK.

4. Murray, P.R., et al. 1995. Manual of Clinical Microbiology , 6th ed. American Society for Microbiology, Washington, D.C.

5. Internet: www.hardlink.com /Bacterial Database Search, February, 1998.

6. Hensyl, B.R., et al. 1990. Stedman's Medical Dictionary , 25th ed. Williams & Wilkins, Baltimore, MD.

7. Koneman, et al. 1997. Color Atlas and Textbook of Diagnostic Microbiology , 5th ed. Lippincott, Philadelphia, PA.

8. Howard, B.J., et al. 1994. Clinical and Pathogenic Microbiology , 2nd ed. Mosby, St. Louis, IL.


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