GI 3

Question 1

in neurologic shellfish poisoning, what is the algae involved

Answer 1

dinoflagellate alage: karenia brevis

compare to the dinoflagellate algae in ciguatera poisoning –> gambierdiscus toxicua aka ciguatoxin

Question 2

what toxin does karenia brevis make

Answer 2

brevetoxin

Question 3

why do you get poisoned by this brevetoxin after you prepare your shellfish

Answer 3

it is not denatured by steaming shellfish

Question 4

incubation period/ duration for neurologic shellfish poisoning and the symptoms

Answer 4

less than 1-3 hours and lasts 24-73 hours

paresthesia, mouth numbness, tingling sensation of mouth and extremities, GI upset

Question 5

toxin in paralytic shellfish poisoning

Answer 5

saxitoxins

Question 6

type of dinoflagellate algae that is seen in paralytic shellfish poisoning

Answer 6

Alexandrium spp., Gymnodinium catenatum, Pyrodinium bahamense, Gonyaulax spp

Question 7

incubation period/duration for paralytic shellfish poisoning and the symptoms

Answer 7

less than 2 hours with 3 day duration
tingling and numbness of mouth spreading to extremities, GI symptoms less common, ataxia,

if severe, muscular paralysis and respiratory paralysis

Question 8

what is big difference in symptoms between paralytic and neurologic shellfish poisoning

Answer 8

in paralytic, GI symptoms are less common

Question 9

type of diarrhea seen in food borne infections

Answer 9

acute watery diarrhea

Question 10

what is the number one cause of traveler’s diarrhea and what is another name for it

Answer 10

e. coli

montezuma’s revenge

Question 11

type of bacteria is e. coli

Answer 11

gram negative anaerobes

Question 12

type of diarrhea is seen in e. coli

Answer 12

dependent on the strain but it is non inflammatory diarrhea

Question 13

symptoms of e.coli poisoning

Answer 13

rapid onset of profuse watery diarrhea with little or no fever

Question 14

treatment of e. coli poisoning

Answer 14

fluid replacement therapy
no antibiotics because of resistance
counsel people of better hygiene especially if in food industry

Question 15

pathogenesis of ETEC (enterotoxigenic e. coli)

Answer 15

• bacteria must colonize the small intestine with specialized fimbrae called CFA (colonization factor antigen)
• CFA allows e. coli to adhere to epithelial cells then release one or both of 2 plasmid encoded enterotoxin
• both toxins are AB - five binding units surrounding a single A active subunit
• B binding subunit attaches to GM1 ganglioside receptor on the brush border which allows A to enter into the cell
• entry –> activated Gs protein adenylate cyclase –> ↑cAMP –> hypersecretion of electrolytes and water outside the cell –> distension and watery diarrhea

Question 16

what are the two toxins that e. coli can release and what are their functions

Answer 16

LT toxin which works on adenylate cyclase

ST toxin which works on guanylate cyclase

Question 17

when does one see enteropathogenic e.coli (EPEC)

Answer 17

childhood diarrhea
seen in developing country
minor cause of traveler’s diarrhea

Question 18

pathogenesis of EPEC (enteropathogenic e. coli)

Answer 18

• you have a plasmid borne (EAF - enteric adherence factor) bundle forming pilus (BFP)
• effacement of microvilli –> leads to loss of absorptive area of the small intestine –> outflux of sodium and chloride –> watery diarrhea

Question 19

how do you treat EPEC diarrhea

Answer 19

rehydration therapy

trimethoprim/fluoroquinolones

Question 20

properties of vibrio cholerae

Answer 20

gram negative rods
motile with single polar flagellum
oxidase positive
O and H antigens (serogroup O1 and O139)
acid sensitive

Question 21

what can vibrio cholerae ferment

Answer 21

ferment sucrose and mannose but not arabinose

Question 22

how does one acquire vibrio cholerae

Answer 22

through food and water with infected human feces

Question 23

pathogenesis of vibrio cholerae

Answer 23

• vibrio cells align close to the microvilli of SI
• cholera toxin is released which is a very potent enterotoxin
• bacteriophage encoded
• AB toxin which is used to bind and get into the cell
• ganglioside GM1 –> activates adenylate cyclase (similar to LT toxin in e. coli) –> increase cAMP –> outflux of water and electrolytes (hypokalemia and metabolic acidosis) –> watery diarrhea (dehydration)

Question 24

why do you have hypokalemia and metabolic acidosis in vibrio cholerae

Answer 24

because of K+ and HCO3- loss

Question 25

features of vibrio cholerae

Answer 25

- rice watery stool (light or pale in color with small fleck or flakes) - excretion of 20-30L diarrhea a day --> hypovolemic shock

Question 26

treatment or management of vibrio cholerae

Answer 26

- oral or admin IV glucose - replace ionic loss --> rehydration therapy - antibiotic like tetracycline to reduce the duration of diarrhea - vaccine (not recommended because it only last 3-6 months) - sanitation and hygiene

Question 27

how do you diagnose vibrio cholerae

Answer 27

thiosulphate-citrate-bile salts-sucrose (TCBS) agar which is a sucrose differentiating agar -if sucrose positive then you know it is vibrio cholerae

Question 28

what does it tell you if thiosulphate-citrate-bile salts-sucrose (TCBS) agar is sucrose negative

Answer 28

vibrio parahemolyticus | vibrio vulnificus

Question 29

cholera antigens serotype

Answer 29

inaba, ogawa, hikojima

Question 30

two different disease you can get from clostridium perfringes

Answer 30

- necrotic enteritis (strain C) | - type A food borne infection (strain A)

Question 31

which one of the clostridium perfringes is more common and how do you get it

Answer 31

- necrotic enteritis is less common and you get from improperly cooked pork - type A food borne infection is more common and you get it from meat or meat products like gravy

Question 32

pathogenesis of clostridium perfringes

Answer 32

spore former so it survives cooking and germinates in meat or meat products --> then we eat it --> spores colonize SI --> produce and release CPE (clostridium perfringes enterotoxin) --> affects permeability of epithelial membrane --> watery diarrhea

Question 33

incubation period and symptoms of clostridium perfringes

Answer 33

incubation is 8-24hrs watery diarrhea and severe abdominal pain NO FEVER, NAUSEA, VOMITING

Question 34

how do you diagnose c. perfringes

Answer 34

enterotoxin in feces large c. perfringes spores in feces large# vegetative cells in incriminated food