Table of Contents
The genus, Vibrio is a member of the family, Vibrionaceae and the most common human pathogens are Vibrio cholerae, V. parahaemolyticus, and V. vulnificus. Vibrio cholerae is a species of Gram-negative, motile, non-sporing, and non-capsulated, facultative anaerobe and comma-shaped bacterium. It is a ubiquitous and abundant aquatic environment. Some strains of V. cholerae are pathogenic to humans and cause the deadly disease cholera, which can be occurred from the consumption of undercooked or raw marine life species. It was first described by Félix-Archimède Pouchet in 1849 and he thought it was some kind of protozoa but later confirmed by Filippo Pacini correctly identified it as a bacterium.
The causative agent of cholera was confirmed by Robert Koch in 1884 whereas Sambhu Nath De isolated the cholera toxin. He demonstrated the toxin as the cause of cholera in 1959. Two serogroups called O1 and O139 are responsible for cholera outbreaks. Diarrhea and vomiting are two clinical features of cholera patients within several hours to 2–3 days of ingestion. Oral rehydration solution (ORS) and antibiotics (fluoroquinolones and tetracyclines) are the common treatment procedure.
Biochemical Tests of Vibrio cholerae
|1. Gram Staining||Gram-Negative Rods (GNRs)|
|6. String Test||Positive|
|7. Catalase test||Positive|
|8. Oxidase test||Positive|
|9. Nitrate reduction test||Positive|
|10. MR (Methyl Red) test||Negative|
|11. VP (Voges- Proskauer) assay||Variable|
|12. OF (Oxidative-Fermentative) test||oxidative/obligate aerobes|
|14. H2S production||Negative|
|15. Indole formation||Positive|
|16. Urease/ urea hydrolysis test||Negative|
|17. Citrate/ citrate utilization||Variable|
|18. DNase test||Negative|
|19. Glucose fermentation||Positive|
|20. Maltose fermentation||Positive|
|21. Lactose fermentation||Variable|
|22. Sucrose fermentation||Positive|
|23. Xylose fermentation||Negative|
|24. Mannitol fermentation||Positive|
|25. Acetate Utilization||Positive|
|26. ONPG (β-galactosidase)||Positive|
|27. Phenylalanine Deaminase (PDA)/PPA Test||Negative|
|28. Lipase test||Positive|
|29. Esculin Hydrolysis test||Negative|
|30. Lysine Decarboxylase Test||Positive|
|31. Ornithine Decarboxylase Test||Positive|
|32. Arginine Dihydrolase Test||Negative|
Keynotes on Vibrio
- Vibrio species are responsible for the majority of human diseases attributed to the natural microbiota of aquatic environments and seafood; the most common pathogenic species are V. cholerae, V. parahaemolyticus, V. vulnificus and V. alginolyticus.
- Vibrio cholerae has two circular DNA and one of them produces the cholera toxin (CT), a protein that causes profuse, watery diarrhea and it is also called rice-water stool.
Rice water stool of a cholera patient
Prepared hanging drop for Darting motility
Hanging drop positive for Darting motility of Vibrio cholerae
Cholera Dipstick Test Positive
Cholera Dipstick Test Negative
Vibrio cholerae growth on TCBS agar of watery diarrhoea culture
Pure well isolated Vibrio cholerae yellow colony on TCBS agar
Gram-negative curved bacillus or comma-shaped Vibrio cholerae in Gram staining of culture
Vibrio cholerae Biochemical Reactions in TSI, SIM, Citrate and Urea agar
Oxidation-fermentation (OF) test and Decaboxylase test of Vibrio cholerae
Vibrio cholerae Antisera for O139 (Bengal), serovar Inaba and serovar Odawa
Vibrio cholerae serotyping for O139 (Bengal)
String Test Positive Vibrio cholerae
Vibrio cholerae colony morphology on nutrient agar
Vibrio cholerae colony morphology on 5% sheep blood agar
Vibrio cholerae colony morphology on MacConkey agar
Vibrio cholerae causing haemodigestion on blood agar
Freshly prepared various culture media for Vibrio cholerae
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