Vibrio
Vibrio
• Vibrio cholerae -gastroenteritis
• Vibrio parahaemolyticus -gastroenteritis, wound infection, bacteremia
Vibrio sp.
Gram-negative rods
C
Curves or comma shapedurves or comma shaped
Non-spore forming
Highly motile-single polar flagella Associated with salt water
Oxidase positive
Facultative anaerobe
Tolerate alkaline conditions to
Tolerate alkaline conditions to
pH9.0
pH9.0
R
Readily cultivatedeadily cultivated,, SSimple imple nutritional requirements
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
• 2 biotypes of serogroup O-1
Classical biotype
El Tor biotype.
V. cholerae
V. cholerae
-
Transmission
food
feces
water
water
Vibrio cholerae
•
Epidemiology
–
Epidemic cholera-spread by
contaminated water under conditions of
poor sanitation
Vibrio cholerae
•
Pathogenesis
–
Ingest 10
8-10
10organisms
–
Non invasive infection of small intestine
–
Organisms secrete enterotoxin
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
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
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
Pathogenicity of V. cholera
•
Dehydration and death
•
Massive secretion of ions/water into
Immunity
Bacteriological Diagnosis
• Specimens: stool, vomitus. • Stained smear
• Culture: alkaline peptone water of agar plate, and TCBS agar plate.
• Quick immunological
methods:
Vibrio-
Prevention and Control
•
Improved sanitation
•
Fluid and electrolyte
replacement
•
Antibiotic prophylaxis
Vibrio parahemolyticus
Vibrio parahemolyticus
• One kind of halophilic vibrios; optimal NaCl One kind of halophilic vibrios; optimal NaCl concentration contained in culture media is 3.5%; concentration contained in culture media is 3.5%; hemolysin related to its pathogenicity, can be detected hemolysin related to its pathogenicity, can be detected by human or rabbit RBC test (Kanagawa test); cause by human or rabbit RBC test (Kanagawa test); cause
food poisoning in human beings. 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
