Vibrio
General Characteristics :
- primarily found in aquatic environments
- pandemics of cholera caused by Vibrio cholerae have occurred since 1817
- occur primarily in Southeast Asia, India, the Middle East, and Africa, but also found in the Mediterranean and occasionally the U.S. Gulf Coast
- infections are associated with consumption of seafood or contact with coastal waters
- can be isolated from a variety of clinical specimens
- spectrum of clinical infections
- gastroenteritis
- cholera – a devastating diarrheal disease
- wound – simple to necrotizing fasciitis
- septicemia
- four species most often seen in labs :
- V. cholerae (serogroup 01 & non-o1)
- V. parahaemolyticus
- V. vulnificus
- V. alginolyticus
- infrequently isolated – good medical hx of :
- recent ingestion of raw seafood
- recent foreign travel
- gastroenteritis with rice-water stools
- accidental trauma during contact with fresh marine water, or products
Cell Morphology :
- gram negative rods
- polar, sheathed flagella with grown in broth, but have peritichous, unsheathed flagella when grown on solid media
- “curved” gram negative rods – usually only seen on the initial gram stain of the specimen
- facultatively anaerobic
- oxidase positive
- most species are halophilic
Vibrio cholerae :
- causative agent of cholera or epidemic cholera
- major public health issue in developing countries
- mainly spread through contaminated water
- portal of entry : mouth
- incubation period : 8 to 48 hours
- organisms reside in small intestine and produce cholera toxin
- symptoms :
- vomiting
- severe, explosive, watery diarrhea
- dehydration and electrolyte loss
- “rice watery stools”
- 10-30 per days
Other Vibrio Infections :
- causative agents : Halophilic vibrios
- V. parahaemolyticus
- diarrheal illness less severe than cholera
- occurs approximately 24 to 48 hours after ingestion of contaminated seafood – particularly oysters
- V. vulnificus
- causes primary septicemia and wound infections
- predisposing risk factors include liver dysfunction and conditions that produce high serum levels of iron
- some type of traumatic injury involving water
- V. alginolyticus
- common inhabitant of marine waters – least likely to be isolated in lab
- involved in eye,ear, and woundd infections associated with contact with sea water
Media Selection :
- culture media should include noninhibitory media and selective media such as thiosulfate citrate bile salts (TCBS) sucrose agar
- enrichment media (alkaline peptone broth with 1% NaCl) may be added
- positive oxidase test differentiates these organisms from the Enterobacteriaceae
- all Vibrio species are susceptible to vibrostatic compound 0/129
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