Lecture 22 Vibrio Flashcards
What are the Vibrio species?
- V cholerae (major)
- V parahemolyticus
- V vulnificus
What are the characteristics of V cholerae?
- Gram-negative bacilli ! Short, curved rods
- Polar flagella
- Highly motile
- Non-spore forming
- Oxidase positive
- Facultative anaerobe
Where is V cholerae found?
- Commonly found in salt water
- Reservoirs : Man, H20
- Biofilms on abiotic surfaces
- Zooplankton, phytoplankton
What is the pathogenicity of V cholerae?
- humans
- oral (water food)
- Enteric pathogen
- small intestine (low tolerance to acid)
- heavy infection dose
- causes cholera
What are some sx of V cholerae?
- Abdominal discomfort
- rush of loose watery stools
- Diarrhea – odorless, mucous flecks
- “Rice water stools”
- Afebrile
- No inflammation
- No injury to bowel mucosa
- Vomiting may occur
What happens if V cholerae is not treated?
- healthy become hypotensive
- infected may die in 3 hrs
- loose stool to shock
How is V cholerae treated?
- fluids, electrolytes
- early rehydration can prevent death
What can be given for V cholerae?
Dried packet formulas : Glucose + NaCl + > physiological concentrations of K+ & Bicarbonate • Secondary role of antibiotics Tetracycline's Trimethoprim sulfamethoxazole Can reduce fluid loss & duration of diarrhea
What is the transmission route of cholera?
- contaminated food or drinking water
- epidemics from feces in water sources
- unsanitary conditions
- raw undercooked fish
How many cholera pandemics have there been?
-8
What is SODIS?
SOLAR WATER DISINFECTION
How can Cholera be prevented?
- modern sewage and water treatments
- eliminated risks
- boil it, cook it, peel it, or forget it
What is a cholera cot?
- plastic cot, with hole leading to collection bucket
- simple device greatly improved cholera treatment
- monitors vomit and stool output
Which variant caused the 7th pandemic in Egypt?
El tor -O1
Which serotype caused the pandemic in Bangladesh, India?
O139 Bengal
What was the source for the outbreak in Haiti?
- Artibonite River
- from a sewage spill from a peace keeping base
What is the Cholera Toxin (CT)?
- Extracellular toxin: released
- Enterotoxin- affects small intestine
- Changes intestinal wall permeability leading to diarrhea
- A-B enterotoxin
- 2 toxic subunits A1 and A2
- five binding subunits (B units)
How are the toxin genes regulated?
- the cholera toxin structural genes (ctx A and ctxB)
- TCP: toxin regulated pilus
- Tox R, Tox S, Tox T
What is Tox R?
Transmembrane protein, binds to operator region of ctx AB operon, activates ctxAB transcription
What is Tox S?
Periplasmic protein, responds to environmental signals, influences ToxR activation of CtxAB
What is Tox T?
-cytoplasmic protein, activates transcription of Tcp operon, ToxT is activated by ToxR
What are some environmental signals that tox responds too?
- pH
- temperature
- bile
- mucus
- osmolarity
What are some oral vaccines for v cholera?
Vaccines 3-
- dukoral
- mORCVAX
- Orochol, now Vaxchora
What are some characteristic of V parahemlytics
- halophilic
- associated with raw sea food and salt water
- summer diarrhea and early fall
- diarrhea like illness
- Do not produce CTX but their own enterotoxin (TDH and TRH)
What are some characteristics of V vulnificus?
- recent emergence
- halophilic, associated with raw sea food and water
- ferment lactose
- scavenge host iron
- cause diarrhea
- wound infections if exposed to sea water
- septicemia
- enters bloodstream, can be fatal
How can cholera be plated?
-Grow well in alkaline media
(pH 8.5-9) & bile salts
-Enrichment media TCBS -Thiosulfate citrate bile salts sucrose agar
