Vibrio!!! MICROM442 Deck 19 Flashcards

1
Q

vibrio cholera are…?

A

SHORT and GMN rods

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2
Q

vibrio cholera have a single…?

A

polar flagella

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3
Q

where do vibrio cholera grow well?

A

alkaline media and in
presence of bile salts (TCBS: thiosulfate citrate bile salts
sucrose agar); low tolerance for acid or drying

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4
Q

history of v.cholera

A

massive watery diarrhea, little abdominal pain, no fever

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5
Q

treatment v.c

A

rehydration

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6
Q

diagnosis of v.c =

A

history

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7
Q

Filippo Pacini

A

ahead of the game, an illness cause by “vibrions”, talented microscopist

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8
Q

Filippo Pacini

A
  • Talented microscopist
  • Noted severe disruption of intestinal mucosa with
    millions of closely associated bacteria
  • Duodenal lesions continued to progress for hrs after
    patient’s death
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9
Q

5th pandemic, vc identified as a causative agent by

A

Robert Koch

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10
Q

Robert Koch described vc as

A

-bacilli present only in the
mucosa of corpses of persons who died of cholera
- Isolated first pure culture: bacilli described as ‘a little
bent, like a comma’
- Able to replicate in moist cloth or damp earth
- Failed to reproduce the disease in non-human animals
- Although bacilli rare in stools during early stages of
cholera, rice-water stools were almost pure cultures

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11
Q

2 serotypes of VC are epidemic and they are

A

O139 and O1 serotypes

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12
Q

which serotype of vs is toxigenic?

A

O139

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13
Q

First 6 pandemics caused by

A

Classical” O1 serotype (O = O-antigen or LPS, 1=first
serotype)
3.2x106 bp/genome, moderate environmental survival, cases/carriers=1:2-4

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14
Q

7th (current) pandemic 1961 in Indonesia, caused by “El Tor” biotype

A

Also O1 serogroup; 2.6x106 bp/genome
much better environmental survival, cases/carriers=1:30-100
3 genomic waves in 7th pandemic
1st estimated to have emerged ~1952
3rd estimated to have emerged in 1988
O139 emerged during 2nd pandemic wave: 1992 in India
can infect adults previously infected with O1 strains

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15
Q

Human colonization creates a hyperinfectious bacterial state which

A

Underscores the role of human-to-human transmission and
rapid spread during outbreaks

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16
Q

No evidence of cholera between outbreaks for vc because

A

Bacteria enter active but not culturable [ABNC] state;
attacked by lytic vibriophages

17
Q

can immunity develop after infection?

A

yes, infx is serogroup specific

18
Q

remove contaminated water or food =

A

remove the epidemic

19
Q

O1 and O139 able to cause epidemic based on which characteristics?

A

-Tcp (type IV) pilus bc needs to attack somehow
-CtxAB (cholera toxin) -> not needed but present in both

20
Q

positive regulator

A

toxRS -> toxT -> tcp pilus (toxT also positively regulates ctxAB) -> ctxAB

21
Q

filamentous phage carry?

A

cholera toxin genes, CTX=AB subunit toxin that catalyzes ADP RIBOSYLATION of stimulatory G-protein during cAMP production

22
Q

CTXø =

A

6.9 kb single-stranded filamentous bacteriophage
carries critical genes involved in virulence

23
Q

cp (toxin co-regulated pilus) is the

A

CTXø surface receptor

24
Q

Bacteriophage production does not cause

A

bacterial lysis or
slow growth

25
Specific binding of CTX to glycolipid GM1, specifically in association with plasma membrane lipid rafts (microdomains in the membrane that are rich in cholesterol), directs CTX “retrograde” transport through what amounts to a reversal of the normal host biosynthetic pathway for secretory and membrane proteins.
* CtxB binds GM1 among lipid rafts on plasma membrane * retrograde transport to golgi- ER * CtxA1 unfolds in ER * translocated into the cytoplasm * ADP ribosylates stimulatory G- protein * increased intracellular [cAMP] * secretion of Cl, H2O * Massive watery diarrhea
26
Retro-translocation of CTX A1-chain relies on hi-jacking the hosts protein quality control system, termed ER-associated degradation, the normal function of which is to direct terminally misfolded proteins to the cytosol for degradation by the proteasome.
a) reduced form of protein disulfide isomerase (PDI) unfolds and dissociates A1 chain b) A1 is released from PDI-A1 complex by oxidation of PDI by the membrane- associated ER- oxidase c) the unfolded A1- chain enters cytoplasm via the protein conducting pore Sec61 d) A1-chain avoids degradation by the proteasome: rapid folding and few lysine residues, which are the targets for ubiquitination (targets proteins for proteasome degradation)
27
CTXø integrates into chromosome I, the larger of the 2 V. cholerae chromosomes AND
Integration is via recombination of CTXø attP at the host sequence attB + Recombination utilizes V. cholerae proteins XerC and XerD
28
CTXø carries
ctxAB
29
clinical symptoms of vc
-severe disease without fever or abdominal pain -watery stool --> shock in 12-24hrs -purge 100% body weight in 4-7days (up to 1 L/hr!) -described as rice water stool: "rice" actually mucous discharge from GOBLET CELLS and eroded GI mucosa -altered consciousness/hypoglycemia/electrolyte imbalances
30
Dx by history
stool exam by dark field/phase contrast for motile organisms Cx is often difficult
31
Rx
treamtnet reduces mortlaity from 50-70% to <0.5%
32
Rx=
-Rehydration: 5g NaCl, 50g pre-cooked rice/liter oral rehydration fluid -7 liter i.v. or 11 liters p.o. is average required rehydration tetra/doxycycline, trimethoprim sulfamethoxazole can reduce fluid loss and duration of diarrhea
33
Vibrio parahemolyticus =
-Halophilic organism, prevalent in salt water during summer and early fall; -Hx: watery/sometimes mucoid/less often bloody diarrhea low grade fever, headache, chills about 24 hrs after ingestion, abdominal pain -Rx: self-limited illness, antibiotics don't help -Dx: history
34
major cause of diarrhea in Japan & associated with raw/undercooked seafood and food contaminated with seawater
Vibrio parahemolyticus
35
Sx of Vibrio parahemolyticus
watery/sometimes mucoid/less often bloody diarrhea low grade fever, headache, chills about 24 hrs after ingestion, abdominal pain
36
secondary cases very uncommon in Vibrio parahemolyticus bc
requires high doses to cause infx; avoided by GOOD SANITATION
37
Vibrio parahemolyticus Dx + Rx
-Dx by History -Rx: supportive care/rehydration