GI infections

Question 1

C. jejuni S/S

Answer 1

liquid stool with gross/occult blood and WBCs

Question 2

C. jejuni reservoir

Answer 2

poultry
cattle
pets

Question 3

S. typhi S/S

Answer 3

typhoid fever: systemic infection

mild cases - gastroenteritis + diarrhea, fever

Question 4

S. typhi reservoir

Answer 4

domestic and wild animals - poultry, swine, cattle, pets

human carriers

Question 5

E. coli O157 S/s

Answer 5

diarrhea

hemolytic uremic syndrome (HUS)

Question 6

C. difficile S/S

Answer 6

asymptomatic to profuse and very watery diarrhea
fever
complication: pseudomembranous colitis, toxic megacolon, rupture

Question 7

Giardia lamblia S/S

Answer 7

asymptomatic to acute self-limited diarrhea

chronic diarrhea with loose, pale stools

Question 8

Giardia lamblia reservoir

Answer 8

beavers and other wild animals

humans

Question 9

Entamoeba histolytica S/S

Answer 9

asymptomatic to bloody/muccoid diarrhea with fever

Question 10

Entamoeba histolytica reservoir

Answer 10

hmans only

Question 11

Food pathogens

Answer 11

C. jejuni
Salmonella typhi
Entamoeba histolytica

Question 12

Contaminated water pathogens

Answer 12

C jejuni
E. coli O157
Giardia lamblia
Entamoeba histolytica

Question 13

Person-to-person pathogens

Answer 13

E. coli O157
C. difficile
Giardia lamblia (cysts)

Question 14

Pathogens that cause inflammatory acute diarrhea

Answer 14

Campylobacter
Shigella
salmonella
EHE.coli
C. diff

Question 15

Pathogens that cause noninflammatory acute diarrhea

Answer 15

Norwalk
rotavirus
C. perfringens
S. aureus
B. cereus
Giardia

Question 16

Common cause of traveller’s diarrhea

Answer 16

ETEC

Question 17

ETEC

Answer 17

expresses ST/LT (heat labile toxin)

Question 18

Hambuger disease

Answer 18

EHEC - Shiga-like toxin

Question 19

Shiga toxin

Answer 19

inactivates ribosomes - affects enterocytes and endothelial cells in kidney glomeruli

Question 20

HUS therapy

Answer 20

supportive

no evidence for antibiotics - may result in cell lysis syndrome

Question 21

Salmonella typhi virulence factors

Answer 21

Vi capsular polysaccharide - prevents phagocytosis
(also a component in vaccine)

can also colonize in gallbladder - difficult to eradicate

Question 22

S. typhi tx

Answer 22

widespread antibiotic resistance

ciprofloxacin / 3rd gen cephalosporin, e.g. ceftriaxone

Question 23

Campylobactor jejuni

Answer 23

most common cause of bacterial gastroenteritis in BC
found in almost all poultry
usually self-limiting, otherwise use macrolides/fluoroquinolones

Question 24

Giardia lamblia pathophys

Answer 24

flattening of villi, loss of SA for absorption
results in intestinal fat malabsorption
NOT invasive - does not cause fever

Question 25

Giardia lamblia tx

Answer 25

metronidazole

Question 26

Entamoeba hystolica tx

Answer 26

metronidazole for trophozoite

intra-luminal agent (iodoquinol/paromomycin) for cysts

Question 27

Cryptosporidium parvum

Answer 27

fecal-oral - pools/body of water
most affect immunocompromised patients
healthy host: self-limiting
immunocompromised: can be severe with profuse watery diarrhea for weeks

Question 28

Cryptosporidium parvum tx

Answer 28

limited options

new drug nitazoxanide - some success

Question 29

Entamoeba histolytica dx

Answer 29

cannot distinguish from E. dispar with stool microscopy

need PCR/ELISA on fresh stool

Question 30

Cryptosporidium parvum dx

Answer 30

stool microscopy

may need special acid-fast stain

Question 31

C. difficile tx

Answer 31

mild/moderate - flagyl + oral vanco
more severe: may need surgery

stool transplant