Vibrio

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Vibrio

• Vibrio cholerae -gastroenteritis
• Vibrio parahaemolyticus -gastroenteritis, wound
  infection, bacteremia
• Vibrio vulnificus -wound infection, bacteremia

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Vibrio sp.

• Gram-negative rods
• Curves or comma shaped
• Non-spore forming
• Highly motile-single polar flagella
• Associated with salt water
• Oxidase positive
• Facultative anaerobe
• Tolerate alkaline conditions to pH9.0
• Readily cultivated, Simple nutritional
  requirements

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Vibrio cholerae

• Antigenic structure
• Common heat-labile flagellar H antigen
• O lipopolysaccharide confers serologic
  specificity
• More than 150 O antigen serogroups
• Only O-1 and 0139 serogroups cause Asiatic
  cholera
• Three serotypes Ogawa, Inaba, Hikojima
• Two biovars classic and El Tor

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• 2 biotypes of serogroup O-1
• Classical biotype
• El Tor biotype.
• Serogroup 139

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V. cholerae - Transmission
feces

• water
• fresh
• salt

• food

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Vibrio cholerae

• Epidemiology
• Epidemic cholera-spread by contaminated water
  under conditions of poor sanitation
• Endemic-consumption of raw seafood
• Copepods

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Vibrio cholerae

• Pathogenesis
• Ingest 108-1010 organisms
• Non invasive infection of small intestine
• Organisms secrete enterotoxin
• Watery diarrhea

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Virulence factors of V.cholerae O1 and O139 Virulence factors of V.cholerae O1 and O139
Virulence factor Biological effect
Cholera toxin Hypersecretic of electrolytes and water
Coregulated pilus Adherence to mucosal cells adhesin
Accessory colonization factor adhesin
Hemagglutination protease Releases bacteria from mucosal cells
Zona occludens Exotoxin
Accessory cholera enterotoxin Exotoxin
Flagellum Motility
Siderophores Iron sequestration
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Cholera toxin

• Enterotoxin-cholera toxin-CtxAB
• Encoded by a prophage
• Molecular mass of 84,000 daltons
• A subunit-ADP-ribosylating toxin
• B subunit-bind GM1-gangliosides on enterocytes
• A subunit ADP ribosylates Gs-alpha which
  regulates activation of adenlyate cyclase
• Result is persistent increase in cAMP levels
• Hyper secretion of Na, Cl, K, bicarbonate and H20

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Vibrio cholerae-Clinical manifestations

• Asymptomatic colonization to fatal diarrhea
• Onset 2-3 days after ingestion
• Abrupt onset of watery diarrhea and vomiting
• Rice water stools
• Severe fluid and electrolyte loss-dehydration,
  metabolic acidosis, hypovolemic shock, renal
  failure
• Death 60 if untreated, 1 if treated for fluid
  loss

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Pathogenicity of V. cholera

• Dehydration and death
• Massive secretion of ions/water into
• gut lumen

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Immunity

• Strong immunity after recovery, SIgA

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Bacteriological Diagnosis

• Specimens stool, vomitus.
• Stained smear
• Culture alkaline peptone water of agar plate,
  and TCBS agar plate.
• Quick immunological methods
  immunofluorescent ball test PCR.

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Vibrio-Prevention and Control

• Improved sanitation
• Fluid and electrolyte replacement
• Antibiotic prophylaxis
• Improved food handling

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Vibrio parahemolyticus

• One kind of halophilic vibrios optimal NaCl
  concentration contained in culture media is 3.5
  hemolysin related to its pathogenicity, can be
  detected by human or rabbit RBC test (Kanagawa
  test) cause food poisoning in human beings.
• raw sea-food

• Clinical manifestations
• Self-limiting diarrhea to mild cholera-like
  illness
• 24 hours after ingestion-explosive water diarrhea
• Headache, abdominal cramps, nausea, vomiting, low
  grade fever for 72 hours or more
• Uneventful recovery
• Wound infections in people exposed to
  seawater-containing vibrios