Vibrio!!! MICROM442 Deck 19

Question 1

vibrio cholera are…?

Answer 1

SHORT and GMN rods

Question 2

vibrio cholera have a single…?

Answer 2

polar flagella

Question 3

where do vibrio cholera grow well?

Answer 3

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

Question 4

history of v.cholera

Answer 4

massive watery diarrhea, little abdominal pain, no fever

Question 5

treatment v.c

Answer 5

rehydration

Question 6

diagnosis of v.c =

Answer 6

history

Question 7

Filippo Pacini

Answer 7

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

Question 8

Filippo Pacini

Answer 8

• 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

Question 9

5th pandemic, vc identified as a causative agent by

Answer 9

Robert Koch

Question 10

Robert Koch described vc as

Answer 10

-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

Question 11

2 serotypes of VC are epidemic and they are

Answer 11

O139 and O1 serotypes

Question 12

which serotype of vs is toxigenic?

Answer 12

O139

Question 13

First 6 pandemics caused by

Answer 13

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

Question 14

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

Answer 14

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

Question 15

Human colonization creates a hyperinfectious bacterial state which

Answer 15

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

Question 16

No evidence of cholera between outbreaks for vc because

Answer 16

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

Question 17

can immunity develop after infection?

Answer 17

yes, infx is serogroup specific

Question 18

remove contaminated water or food =

Answer 18

remove the epidemic

Question 19

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

Answer 19

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

Question 20

positive regulator

Answer 20

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

Question 21

filamentous phage carry?

Answer 21

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

Question 22

CTXø =

Answer 22

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

Question 23

cp (toxin co-regulated pilus) is the

Answer 23

CTXø surface receptor

Question 24

Bacteriophage production does not cause

Answer 24

bacterial lysis or
slow growth

Question 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.

Answer 25

• 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

Question 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.

Answer 26

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)

Question 27

CTXø integrates into chromosome I, the larger of the 2 V. cholerae
chromosomes AND

Answer 27

Integration is via recombination of CTXø attP at the host sequence
attB +
Recombination utilizes V. cholerae proteins XerC and XerD

Question 28

CTXø carries

Answer 28

ctxAB

Question 29

clinical symptoms of vc

Answer 29

-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

Question 30

Dx by history

Answer 30

stool exam by dark field/phase contrast for motile organisms
Cx is often difficult

Question 31

Rx

Answer 31

treamtnet reduces mortlaity from 50-70% to <0.5%

Question 32

Rx=

Answer 32

-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

Question 33

Vibrio parahemolyticus =

Answer 33

-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

Question 34

major cause of diarrhea in Japan & associated with raw/undercooked seafood and food contaminated with seawater

Answer 34

Vibrio parahemolyticus

Question 35

Sx of Vibrio parahemolyticus

Answer 35

watery/sometimes mucoid/less often bloody diarrhea
low grade fever, headache, chills about 24 hrs after ingestion,
abdominal pain

Question 36

secondary cases very uncommon in Vibrio parahemolyticus bc

Answer 36

requires high doses to cause infx; avoided by GOOD SANITATION

Question 37

Vibrio parahemolyticus Dx + Rx

Answer 37

-Dx by History
-Rx: supportive care/rehydration