Cholera

Clinical features
Rice watery stool (painless)
Severe dehydration  with following features
Tready pulse
Sunken eyes
Skin turgor decreased
Low blood pressure
Causative agent: Vibrio cholerae

Laboratory diagnosis
Stool sample for culture

Stool sample inoculated into alkaline peptone water and hanging drop done after 6 hrs

Hanging drop showing darting motility is suggestive of Vibrio cholerae

Then the broth is plated onto TCBS and MacConkey
After overnight incubation
TCBS- yellow coloured colonies
MacConkey- non lactose fermenting colonies 
Further identification 
Gram stain - gram negative curved bacilli
Oxidase- positive 
Indole- positive
TSI- A/A no gas and no H2S 
Citrate - positive 
Urease- negative
Mannitol - fermented 

Cholera red reaction - innoculate peptone water with few colonies of Vibrio cholerae
After overnight  incubation add few drops of concentrated H2SO4 along the sides of the test tube a red colour ring is formed indicating nitrosoindole ring 

Confirmatory test
Agglutination with antisera
1. Polyvalent O
2. Ogawa
3. Inaba
4. Hikojima