2. Gram-negative, oxidase positive,
short, rigid
Curved rods or comma shaped
Highly motile-single polar flagella
Vibrios Vibrare Vibrate
present in marine environments &
surface waters worlwide.
The most important member of the
genus is Vibrio cholerae
Dr. Rakesh
Gram-negative, oxidase positive,
short, rigid
Curved rods or comma shaped
Highly motile-single polar flagella
Vibrios Vibrare Vibrate
present in marine environments &
surface waters worlwide.
The most important member of the
genus is Vibrio cholerae
4. Non-Halophilic Vibrios
- V. cholerae O1 classical and El Tor biotype
- Non O1 V. cholerae Non cholera vibrio (NCV) or non-
agglutinating vibrio (NAG)
Halophilic Vibrios
- V. parahaemolyticus
- V. alginolyticus
- V. vulnificus
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9. Physiology
Facultative anaerobic
Asporogenous & noncapsulated.
Growth stimulated by NaCl
pH 6.4 – 9.6 (optimum 8.2).
Acid labile
Temperature 16 - 400
C
(Optimum 370
C)
It grows well on ordinary media.
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10. Ordinary media
- Nutrient Agar
- MacConkeys agar
- Blood Agar
- Peptone water
- Gelatin stab culture
Special Media
- Transport media VR medium, Cary blair medium
- Enrichment media Alkaline peptone water,
Monsur’s taurocholate tellurite peptone water,
- Plating media Alkaline bile salt agar, GTTA, TCBS
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11. Peptone Water:
Incubated at 37°C, it forms a fine surface pellicle in 6-9 hrs.
Nutrient Agar:
moist and translucent colonies, 1-2 mm in diameter after 18-
24 hrs, bluish tinge in transmitted light.
Blood Agar:
non hemolytic, but some strains may produce zones of
haemolysis
MacConkey’s Agar:
Most strains grow well giving pale i.e., non lactose fermenting
colonies in 24-36 hrs. but later on pink on prolonged
incubation
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12. VR medium
pH 8.6 to 8.8, do not multiply but remains viable for several
weeks.
Cary-Blair medium
Disodium phosphate, sod thioglycolate, NaCl, CaCl2,
pH 8.4, Salmonella, Shigella, Vibrio
Monsur’s gelatin taurocholate trypticase tellurite agar
(GTTA) medium, pH 8.5
small, transulcent with greyish black centre and a tubid halo
around colonies hydrolysis of gelatin.
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13. Selective Medium – TCBS
V. cholerae grows well on
Thiosulphate citrate
Bile salts sucrose (TCBS )
agar, on which it
produces yellow
colonies that are readily
visible against the dark
green background of
the agar.
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15. Antigenic Structure & Properties
Many vibrios show a single heat labile, flagellar (H) antigen.
Antibodies to H antigen not protective in susceptible hosts.
The somatic polysaccharide (O) antigen used to subdivide Vibrio
species into serogroups is of fundamental importance in the identification
of this organism.
There are > 140 serotypes of V. cholerae, (O1 – 140),
7 - O groups of V. vulnificus and 13 O serogroups of V.
parahaemolyticus.
V. cholerae O1, or O139 (Bengal strain) are the causative agents of
cholera epidemics.
Most of the other serotypes are harmless.
Antigenic variation plays an important role in the epidemiology and
virulence of cholera.
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19. Vibrio cholerae - Enterotoxin
V.cholrae produce heat labile enterotoxin with a Moll wt. of about
84,000 consisting of sub units A ( MW 28,000 ) and B
Ganglioside GM1 serves as a mucosal receptor for subunit B,
which promotes entry of subunit A into the cell
Activation of subunit A1 yields increased levels of intracellular
cAMP and results in prolonged hyper secretion of water and
electrolytes
There is increased sodium dependent chloride secretion, and
absorption of sodium and chloride is inhibited
The genes for V.cholrae Enterotoxin are on the bacterial
chromosome
Cholerae Enterotoxin is antigenically related to LT of Escherichia
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20. Modes of Transmission
Water (infectious dose = 109
)
Food (infectious dose = 103
)
Person-to-person
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22. Pathogenesis
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The ingested organisms pass through the acid barrier of the stomach
multiply in the alkaline medium of the small intestine.
Produces Enterotoxin and the disease
Do not penetrate deep into the gut and there is no bacteraemia
Adhere with the epithelium by special fimbriae such as the toxin co-
regulated pilus (TCP)
Enterotoxin and TCP are regulated by the Tox R gene product, Tox R
protein
24. Massive loss of water & electrolytes (Sodium and bicarbonate)
by action of enterotoxin leads to :
- Dehydration
- haemoconcentration,
- anuria,
- hypovolemic shock
- Base deficit acidosis & muscle cramps due to hypokalaemia
In untreated cases mortality rate 60-70% due to renal failure.
Dr. Rakesh
27. Laboratory Identification of Vibrios
Transport medium or holding medium
- Cary-Blair
-Venkatraman Ramakrishnan medium- liquid
Direct Microscopy Hanging drop darting
motility
Enrichment medium - alkaline peptone broth
29. Yellow colonies on TCBS
Selective/differential culture
medium - TCBS agar
- V. cholerae grow as
yellow colonies
- Gram stain
- Biochemical and
serological tests
- Motility- Darting motility
on hanging drop
preparation
30. String Test
The string test may be performed
on a glass microscope slide or
plastic petri dish by suspending
18 to 24 hour growth from Heart
Infusion Agar (HIA) or other non-
inhibitory medium in a drop of
0.5% aqueous solution of sodium
deoxycholate.
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32. Vaccination
Killed parenteral vaccine
- 12,000 million V. cholera per ml
- Equal no. of Inba & Ogwa strains
- 2 inj intramuscularly at interval of 4 weeks
- 50-60%
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33. Killed Oral Vaccine
- B subunit whole cell (BS-WS) vaccine
- Heat killed classical vibrio (both Inba & Ogwa)
- Formalin killed EL Tor Vibrio (both Inba & Ogwa)
- 85% for 1 yr
- 60% for 2 yrs
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34. Halophilic Vibrios
Can not grow in media lacking sodium choride.
Natural habitat is sea water and marine life.
E.g. V. parahaemolyticus, V. alginolyticus, V. vulnificus.
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35. Vibrio parahaemolyticus
First isolated in Japan in 1951 as causative agent of food poisoning due to
consumption of seafood.
Isolated from shell fish, shrimps, crabs and mulluscs.
Optimum NaCl concentration 2-4%, (tolerate upto 8%).
Do not ferment sucrose so yellow colour colonies on TCBS medium.
All strains are not pathogenic for man.
strains environment non hemolytic high salt agar
(Wagatsuma agar)
Strains humans hemolytic Kanagawa phenomenon
Causes food poisioning, acute diarrhoea, abdominal pain vomiting and
dehydration
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36. Vibrio alginolyticus
Frequently found in sea fish
Role in human lesion is uncertain.
Resembles parahaemolyticus
- Higher salt tolerance (up to 10%)
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37. Vibrio vulnificus
Designated as L+ vibrio for its ability to ferment lactose.
It resembles V. parahaemolyticus but ferments lactose and
has salt tolerance of less than 8%.
Cuses wound infection and cellulitis following exposure to
seawater.
Ingestion of under-cooked or raw seafood penetrates the
gut mucosa without causing GIT manifestations
blood stream septicemia high mortality rate.
Dr. Rakesh