MMI 301: Lecture 16 Vibrio

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MMI 301: Lecture 16 Vibrio
2013-11-01 12:05:21
MMI 301

MMI 301
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  1. Vibrio Species
    • Human: cholerae, vulnificus, parahaemolyticus
    • Marine animal: salmonicida, anguillarum, shiloi
    • Benefecial symbionts: harveyi, logei, fischeri
  2. Dudley
    Town in which in 1831 massive cholerae outbreak killed alot of people
  3. Mt. Healthy
    Previously Mt. Pleasant, people fled here Cincinnati during outbreak of 1849-1851
  4. Cholera Fumigating Box
    Used to disinfect people that left infected districts. Railways, used carbolic acid and chloride of lime fumes to disinfect
  5. Who discovered cholera transmission vector
    • John Snow
    • Published findings in 1849
    • Convinced officials to remove 'infected' tap, cured epidemic
    • Most people still though it was miasmata
  6. Who discovered cholerae
    • Filippo Pacini was given honor 82 years after death
    • Originally everyone credited Koch
    • No one ever saw his stuff (1854)
  7. Vibrio cholerae Morphology
    • Gram - curved rod
    • Highly motile (polar flagellum)
    • High salt tolerance
    • Low acid tolerance
    • Many O serotypes (different LPS O-antigens)
    •     -O1 and O139 are epidemic strains
    • Only one H antigen (flagellar)
  8. How is water infected? (cholerae)
    Originally believed to be only through feces, now linked with copepods and diatoms
  9. Cholera Symptoms
    • Sudden onset vomiting and diarrhea
    •    -"rice water" stools, colorless, fishy odor, mucus
    • Rapid Dehydration occurs, leads to hypovolemic shock
    • Loss of skin turgor
  10. Sari cloth
    Cloth filters used to filter water from cholerae, not totally effective, but kind of effective
  11. Cholerae Pathogenesis
    • Ingested, acid shock and increased temp induce virulence gene regulation through ToxR regulator
    • ID50 = 108, sensitive to low stomach pH
    • Toxin co-regulated pili (TCP)/mucinase permit adherence to ileum
    • Cholera toxin (CT): causes secretory diarrhea. May be more toxins: Zot/Ace
    • No apparent tissue destruction
    • Shed in high numbers in rice water stool
  12. Cholera Toxin (CT)
    • AB5 hexameric protein
    •      -Virulence in A, binding in B
    •      -B unit is pentamer
    • E coli heat-labile LT enterotoxins are same family
    • CT B5 binds GM1 gangliosides
    • A subunit carries out ADP-ribosylation of membrane-bound G signalling protein
    •       -G protein cannot shut off associated adenyl cyclase
    • Elevated cAMP powers active transport of electrolytes/water out of cells
  13. GM-1 ganglioside
    Normally pump water/electrolytes out of lumen and into bloodstream, cholera toxin reverses this
  14. How many chromosomes in cholerae
  15. Where does gene for cholera toxin come from
    Phage- CTXφ
  16. tcp Cluster
    Genomic island in cholerae
  17. Cholera Pandemics
    • 7 since 1800s
    • Originate in bay of Bengal
    • Most recent was in 1990s in Americas, came over with ballast water from south east asia
    • By 1995, 1 million cases, 10,000 deaths
  18. Cholera cases yearly
    3-5 million, 100,000 deaths
  19. Cholera Treatment
    • Re hydration with IV of ORS (oral rehydration solution) 
    •     -ORS=sodium/glucose 1 sachet ORS in 1 litre water
    •          -can be half spoon salt/6 spoons sugar per liter water
    • Antibiotics not needed
    •     -Tetracycline, ciprofloxacin, azithromicin common
  20. Cholera vaccines
    • Dukoral:
    •       -killed whole cells of cholerae O1 plus recombinant cholera toxin B subunit
    • Shanchol:
    •       -killed whole cells O1 and O138
    • Provide 50% protection for 2 years, administered as two innocs. 1-6 weeks apart
    • Orochol: live attenuated strain from 596B presented as single dose
    •       -Effectiveness after 8 days, can be used at first signs of outbreak
  21. Vibrio parahemolyticus
    • Infection through contaminated sea-water consumption
    • Gastroenteritis
    • Explosive, watert diarrhea for 3 days
  22. Vibrio vulnificus
    • Causes rapidly progressing infection
    • Fatal w/o antibiotics in 50% of patients
    • Infects wounds with seawater