B5.020 - Prework Diarrheal Pathogens

Question 1

name the orgs that cause secretory gastroenteritis

Answer 1

vibrio cholerae

ETEC

Clostridium perfringens

Bacillus cereus

Staph aureus

Question 2

describe mechanism of secretory gastroenteritis

Answer 2

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

Question 3

what orgs cause inflammatory gastroenteritis

Answer 3

shigella

EHEC

Salmonella NOT TYPHI

Vibrio parahaemolyticus

C. diff

campylobacter

Question 4

mechanism of inflammatory diarrhea

Answer 4

bacterial invasion or cytotoxins cause mucosal damage that leads to inflammation

Question 5

orgs responsible for invasive gastroenteritis

Answer 5

salmonella typhi

yersinia enterocolitica

Question 6

mechanism of invasive gastroenteritis

Answer 6

bacteria penetrate the mucosa and invade the reticuloendothelial system

Question 7

describe vibrio

Answer 7

gram - curved rods

motile

oxidase +

common inhabitants of marine environments

many are halophilic

Question 8

3 major human vibrio pathogens

Answer 8

v. cholerae
v. parahaemolyticus
v. vulnificus

Question 9

which vibrio causes gastroenteritis

Answer 9

v. cholerae

Question 10

which vibrio cause wound infections, septicemia, cellulitis

Answer 10

v. parahaemolyticus
v. vulnificus

Question 11

what is cholera

Answer 11

profuse, watery diarrhea “ricewater stools”

caused by toxin producing strains of v. cholerae

Question 12

what serotypes of v. cholerae produce cholera

Answer 12

O1 and O139

Question 13

epidemiology of cholera

Answer 13

endemic to south asia

8 cholera pandemics in last 200 years

v. cholerae is only vibrio that can grow without salt

Question 14

what is v. cholerae O1

Answer 14

El Tor

Question 15

what is O139

Answer 15

Bengal

Question 16

which pandemic strain made it to Haiti

Answer 16

O1 El Tor

Question 17

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

Answer 17

Haiti

Napaleses downstream river of UN camp

DR

MX

Cuba

Question 18

describe Cholera in the US

Answer 18

Most cases imported

100 documented/yer, 5000 estimated undocumented

associated with consumption of shellfish

Question 19

describe transmission of cholera

Answer 19

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

Question 20

virulence factors of cholerae

Answer 20

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

Question 21

describe the pathogenesis of cholera on a micro level

Answer 21

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

Question 22

clinical manifestations of cholera

Answer 22

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)

Question 23

loss of fluid and electrolytes due to cholera leads to what

Answer 23

dehydration

acidosis

hypokalemia

hypovolemic shock

cardiac arrhythmia

renal failure

death in 50-60% untreated pts

spontaneous resolution in 5-7 days

Question 24

lab dx of cholera

Answer 24

microscopy of stool specimen

culture selective for vibrio - TCBS

agglutination with O group 1 or 139

Question 25

confirmed case of vibrio requires what

Answer 25

**O group 1 or group 139 antigen** and **CT production**

Question 26

cholera treatment

Answer 26

rehydration tharapy oral rehydration salts (NaCl, KCl, NaHCO3, glucose) antibiotics can speed - ceftriaxone, doxycycline, azithro for pregnant, kids

Question 27

cholera prevention

Answer 27

good public sanitation **Boil it, cook it, peel it or forget it** **vaccine - contains killed O1 and rCTB B subunit** **(aso prevents ETEC)**

Question 28

describe v. parahaemolyticus epidemiology and what its associated with

Answer 28

common inhabitant of **coastal waters** most common in **summer months** infections associated with raw or undercooked seafod esp oysters

Question 29

describe disease from v parahaemolyticus

Answer 29

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

Question 30

lab culture of v parahaemolyticus

Answer 30

halophilic TCBS

Question 31

describe v. vulnificus

Answer 31

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

Question 32

Answer 32

v. vulnificus

Question 33

who gets v. vulnificus and how is it treated

Answer 33

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

Question 34

what are aeromonas and plesiomonas

Answer 34

can cause GI disease, wound infections, invasive infections gram - rod shaped, facultative anaerobes associated with fresh, brackish water (NOT SALT)

Question 35

who gest disease from aeromonas and plesiomonas

Answer 35

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

Question 36

describe anaerobes

Answer 36

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)

Question 37

why dont anaerobes grow in oxygen

Answer 37

high redox potention of tissues due to dissolved O2

Question 38

describe tersinia

Answer 38

gram - non motile, non spore forming

Question 39

describe where yersinia is found

Answer 39

common cause of enteritis in colder climates consumption of **undercooked pork, chitlins,** ubiquitous in soil and **pigs** majority in kids under 4

Question 40

describe yersinia growth

Answer 40

can grow in wide range of temps, 1C-40C motile at 25, non motile at 37C

Question 41

describe yersinia diseases

Answer 41

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**

Question 42

virulence factors of yersinia

Answer 42

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

Question 43

treatment and prevention of yersinia

Answer 43

safe food handling GE is usually self limited and treatment is **symptom based and supportive** antibicrobial treatment for sever septicemia DOC - ceftriaxone