This document discusses Vibrio cholerae, the bacteria that causes cholera. It outlines the cultural characteristics and growth conditions of V. cholerae, describing various media used for transport, enrichment, and plating. It also summarizes the pathogenesis of cholera, describing how V. cholerae infection occurs and causes diarrhea through cholera toxin. Laboratory diagnosis methods are provided, including microscopic examination, cultural studies, and biochemical tests to identify the bacteria. Treatment involves fluid replacement therapy and oral rehydration.

2. Department of pathology

4. MORPHOLOGY

5. CULTURAL CHARACTERISTICS
They are aerobics facultative
anaerobes growing well in the
temperature of 37 degree C and in the
Ph of 7.4 - 9.6

6. ORDINARY MEDIA
 NUTRIENTAGAR MEDIUM
 MACCONKEYAGAR MEDIUM
 BLOODAGAR MEDIUM
 GELATIN STAB CULTURE

7. SPECIAL MEDIA
 TRANSPORT MEDIA
 VR medium
 Bile peptone transport medium
 Cary blair medium
 ENRICHMENT MEDIA
 Alkaline peptone water
 Monsur’s medium
 PLATING MEDIA
 Alkaline bile salt agar medium
 Monsur’s gelatin taurocholate trypticase tellurite agar medium
 Thiosulphate citrate bile sucrose agar medium

8. ORDINARY MEDIA
 NUTRIENT AGAR MEDIUM
After overnight incubation round,
moist, translucent, bluish colonies will be
appear with 1-2mm size.

9. MACCONKEY AGAR MEDIUM
 Colorless colonies will be form after that it
will change to pink color.

10. BLOOD AGAR MEDIUM
 A zone of green discoloration appears
around the colonies at first and later it
become clear.

11. GELATIN STAB CULTURE
 After three days of incubation a white line of
growth appears in the medium

12. TRANSPORT MEDIA
 VENKATRAMAN - RAMAKRISHNAN MEDIUM
⚫This is an ideal transport medium.
⚫The organism will be viable in this
medium for several weeks without
multiplication

13. ENRICHMENT MEDIA
 ALKALINE PEPTONE WATER
Rapid growth occurs in about 6 hours with
formation of thick surface pellicle.

14. PLATING MEDIA
 ALKALINE BILE SALTAGAR MEDIUM
It is a modified nutrient agar medium and the
colonies are similar that appears in the nutrient agar
medium.

15. MONSUR’S GELATIN TAUROCHOLATE
TRYPTICASE TELLURITE AGAR MEDIUM
 After 24 hours of incubation small colonies will be
formed with 1-2 mm in size and grayish color with
black centers.
 The size will be increased to 3-4 mm after 48 hours
of incubation.

16. THIOSULPHATE CITRATE BILE SUCROSE AGAR
MEDIUM
 In this medium large colonies will be formed in
yellow color.
 Later the yellow color will be changed to green
color.

17. PATHOGENESIS
 Vibrio cholerae is the causative agent of the
diarrheal disease cholera.
 The disease is characterized by sudden
effortless vomiting, profuse rice water stool
followed by rapid dehydration.

18.  Infection occurs in humans via oral route by
ingestion of contaminated food or water.
 Incubation period is 6hours to 3 days.
 The ingested micro organism reaches to the
stomach and the multiplication occurs in the small
intestine.
 After the growth and multiplication it starts to
produce toxins namely, “cholera toxin” or “cholera
enterotoxin” or “choleragen”

19.  This toxins cause the hyper secretion of glands in
the intestine and resulting in large amount of
intestinal fluids in the intestinal lumens.
 The toxin also increases the capillary permeability
leading to edema.
 On the same hand it produces proteolytic enzymes,
which help the organism to penetrate the covering
of GI tract and causes the diarrheal disease among
humans.

20.  The stools are rice water similar which containing
mucous, epithelial cells and large number of
vibrios.
 The massive loss of electrolytes from the body
leads to metabolic acidosis, muscle cramps, anuria,
acute tubular necrosis, shock and some times
death.
 The disease may last for 4-5 days with an average
fluid loss of 15-20 liters per day.

21. LABORATORY DIAGNOSIS
 Hematological investigations:
no significant abnormalities
 Bacteriological examination
1, microscopic examination
2, cultural studies
3, biochemical test
4, slide agglutination test

22. MICROSCOPIC EXAMINATION
 Under the microscope can observe gram negative
comma shaped bacilli.

23. CULTURAL STUDIES
 Ordinary media, transport media and enrichment
media can be use for the culture studies.
 In macconkeys medium pale color colonies will
developed.
 In mansur medium colonies will be formed with
black centers.

24. BIOCHEMICAL TESTS
 Sugar fermentation test: fermentation of glucose,
sucrose and maltose will occur with the production
of gas.
 Nitrate reduction test: positive
 Iodole test: positive
 Catalase test: positive
 Oxidase test: positive
 Motility test: positive

25. SLIDE AGGLUTINATION TEST
 The specimen from a selective media is placed on
a microscopic slide and add a drop of normal saline
over that and then observe under a microscope
after adding one drop of antiserum over the
specimen.
 Presence of clumps indicates the positive test.

27. TREATMENT
 Adequate fluid and electrolyte replacement is
necessary for such patients which is known as fluid
replacement therapy.
 Oral rehydration therapy.