Vibrio cholerae

Vibrio cholerae: Dr.Jawad Kadhim Tarrad
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Important properties:
• Gram-negative rod in comma-or S-shaped.
• Non capsulated.
• It is active motile by single flagellum.
• Facultative anaerobic.


Antigenic structure and virulence factors:
• Somatic antigen(O-antigen): V. cholerae has many antigenic groups according to O-antigen. Only serogroup-O1 and O139 members were associated with severe diarrhea and epidemic cholera. Other serogroups, non-O1 and non-O139, are either non-pathogenic or cause mild diarrhea.
V.cholerae O1 has two biotypes; El-Tor and classical cholera. Each biotype divided into three serotypes: Ogawa, Inaba and Hikojima.
• Flagella (H-antigen) and Mucinase allow the organism to migrate and penetrate thick mucous layer that cover intestinal epithelial cells and it migrates through mucous layer.
• Cholera toxin is major virulence factor and it consists of two subunits (2A-5B). The A-subunit consist of two units (A1 and A2). The B-subunit is composed of five identical units arranged in ring around central subunit A. The A-subunit linked to B-subunit by disulfide bond.
Source and transmission:
• Natural habitats are human intestine.
• The organism is transmitted from person to person by ingestion of fecal contaminated water and food.
• V.cholerae proliferates in summer months when water temperature more than 20C (warm water ), therefore most cases occur in warm months.