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GIR Test 1 > B5.020 - Prework Diarrheal Pathogens > Flashcards

B5.020 - Prework Diarrheal Pathogens Flashcards

1
Q

name the orgs that cause secretory gastroenteritis

A

vibrio cholerae

ETEC

Clostridium perfringens

Bacillus cereus

Staph aureus

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2
Q

describe mechanism of secretory gastroenteritis

A

enterotoxin or bacterial adherance/invasion causes shift in water and electrolyte excretion/adsorption

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3
Q

what orgs cause inflammatory gastroenteritis

A

shigella

EHEC

Salmonella NOT TYPHI

Vibrio parahaemolyticus

C. diff

campylobacter

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4
Q

mechanism of inflammatory diarrhea

A

bacterial invasion or cytotoxins cause mucosal damage that leads to inflammation

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5
Q

orgs responsible for invasive gastroenteritis

A

salmonella typhi

yersinia enterocolitica

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6
Q

mechanism of invasive gastroenteritis

A

bacteria penetrate the mucosa and invade the reticuloendothelial system

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7
Q

describe vibrio

A

gram - curved rods

motile

oxidase +

common inhabitants of marine environments

many are halophilic

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8
Q

3 major human vibrio pathogens

A

v. cholerae
v. parahaemolyticus
v. vulnificus

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9
Q

which vibrio causes gastroenteritis

A

v. cholerae

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10
Q

which vibrio cause wound infections, septicemia, cellulitis

A

v. parahaemolyticus
v. vulnificus

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11
Q

what is cholera

A

profuse, watery diarrhea “ricewater stools”

caused by toxin producing strains of v. cholerae

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12
Q

what serotypes of v. cholerae produce cholera

A

O1 and O139

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13
Q

epidemiology of cholera

A

endemic to south asia

8 cholera pandemics in last 200 years

v. cholerae is only vibrio that can grow without salt

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14
Q

what is v. cholerae O1

A

El Tor

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15
Q

what is O139

A

Bengal

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16
Q

which pandemic strain made it to Haiti

A

O1 El Tor

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17
Q

where was the O1 El Tor found after the haiti earth quake

A

Haiti

Napaleses downstream river of UN camp

DR

MX

Cuba

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18
Q

describe Cholera in the US

A

Most cases imported

100 documented/yer, 5000 estimated undocumented

associated with consumption of shellfish

19
Q

describe transmission of cholera

A

requires high infectious dose of 10^8

person to person is rare

epidemics associated with poor sanitation, usually fecal contamination of wajter supply

sporadic cases often associated with shellfish

20
Q

virulence factors of cholerae

A

flagella - necessary to swim toward epithelium

toxin coregulated pili (TCP) - necessary for bacterial attachment to epithelium of small intestine

Cholera toxin (CT) - an AB toxin responsible for symptoms of cholera

21
Q

describe the pathogenesis of cholera on a micro level

A

flagellum help the bug swim towards epithelium, it attaches using TCP and then CT uses AB toxin system to insert toxin which blocks GTPase activity of Gs activating cAMP and allowing for electrolyte secretion

22
Q

clinical manifestations of cholera

A

incubation period mean 2 days

abrupt onset of diarrhea, abdominal cramps, nausea, vomiting

fever usually absent

diarrhea can range from water to “ricewater” (fluid + mucus + vibrios)

23
Q

loss of fluid and electrolytes due to cholera leads to what

A

dehydration

acidosis

hypokalemia

hypovolemic shock

cardiac arrhythmia

renal failure

death in 50-60% untreated pts

spontaneous resolution in 5-7 days

24
Q

lab dx of cholera

A

microscopy of stool specimen

culture selective for vibrio - TCBS

agglutination with O group 1 or 139

25
Q

confirmed case of vibrio requires what

A

O group 1 or group 139 antigen and CT production

26
Q

cholera treatment

A

rehydration tharapy

oral rehydration salts (NaCl, KCl, NaHCO3, glucose)

antibiotics can speed - ceftriaxone, doxycycline, azithro for pregnant, kids

27
Q

cholera prevention

A

good public sanitation

Boil it, cook it, peel it or forget it

vaccine - contains killed O1 and rCTB B subunit

(aso prevents ETEC)

28
Q

describe v. parahaemolyticus epidemiology and what its associated with

A

common inhabitant of coastal waters

most common in summer months

infections associated with raw or undercooked seafod esp oysters

29
Q

describe disease from v parahaemolyticus

A

gastroenteritis similar to mild cholera sometimes with low grade fever

self limiting in 3-5 days

pts with immunodeficiencies or liver disease can be treated with doxy and cetriaxone

wound infections from exposure to sea water

30
Q

lab culture of v parahaemolyticus

A

halophilic

TCBS

31
Q

describe v. vulnificus

A

similar to v. haemolyticus in distribution/transmission

more likely to cause invasive disease

pts experience fever and chills

more aggressive skin and soft tissue infections

32
Q
A

v. vulnificus

33
Q

who gets v. vulnificus and how is it treated

A

pts with DM, liver disease or immune dysfunction mroe likely to develop bacteremia

up to 50% fatality rate

treat septic or compromised pts with doxy or 3rd gen ceph

34
Q

what are aeromonas and plesiomonas

A

can cause GI disease, wound infections, invasive infections

gram - rod shaped, facultative anaerobes

associated with fresh, brackish water (NOT SALT)

35
Q

who gest disease from aeromonas and plesiomonas

A

associated with consumption of contaminated food (fish, shellfish) or water

foreign travel

36
Q

describe anaerobes

A

most anaerobic pathogens are aerotolerant meaning they tolerate brief exposure to variable O2 leves, some have SOD and catalase, NADH oxidoreductase (turns O2 to water)

37
Q

why dont anaerobes grow in oxygen

A

high redox potention of tissues due to dissolved O2

38
Q

describe tersinia

A

gram - non motile, non spore forming

39
Q

describe where yersinia is found

A

common cause of enteritis in colder climates

consumption of undercooked pork, chitlins, ubiquitous in soil and pigs

majority in kids under 4

40
Q

describe yersinia growth

A

can grow in wide range of temps, 1C-40C

motile at 25, non motile at 37C

41
Q

describe yersinia diseases

A

gastroenteritis - 1-10 d incubation, symptoms for 1-2 wks

mesenteric adenitis - mimics acute appendicitis

blood transfusion related - bacteremia and endotoxic shock, due to growth of yersinia in contaminated refrigerated blood

42
Q

virulence factors of yersinia

A

Heat stable enterotoxin

Yops - T3SS and effectors, plasmid coated

Invade M cells of Peyers patches

Inv - a chromosomally encoded protein required for invasion of non phagocytic cells

move to mesenteric lymph nodes which can become intensly swollen

intestinal inflammation can lead to bloody diarrhea

43
Q

treatment and prevention of yersinia

A

safe food handling

GE is usually self limited and treatment is symptom based and supportive

antibicrobial treatment for sever septicemia

DOC - ceftriaxone

GIR Test 1 (15 decks)

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