Bacterial GI Infections

Question 1

differentiate 3 classes of enteric bacterial pathogens

Answer 1

enteroinvasive: facultative intracellular

enterotoxic- bacteria produce enterotoxin, not invasive

enteropathogenic- bacteria destroy epithelium, invasion does not play a role

Question 2

signs for inflammatory damage

Answer 2

pus, PMNs in feces

Question 3

causes of inflammatory damage

Answer 3

baterial invasion and intracellular replication

bacterial toxins

Question 4

secretory diarrhea, causes

Answer 4

high volume, caused by bacterial toxins

Question 5

main tx for diarrhea

Answer 5

rehydration

Question 6

sx of enteroinvasive infection

Answer 6

painful cramping, stools containing blood and pus

Question 7

5 examples of enteroinvasive

Answer 7

salmonella enterica, shigella, campylobacter jejuni, listeria monocytogenes, EIEC

Question 8

lactose macconkey use

Answer 8

only G- grow

pink means Lac+, yellow is Lac-

Question 9

differentiate 4 outcomes for TSI slants, examples of microbes for each

Answer 9

K/K- ferment no lactose, sucrose, or glucose
-pseudomonas

A/A- ferments all 3
-E coli, Klebsiella, enterobacter

K/A-glucose only
-salmonella, shigella

black precipitate- H2S production, salmonella and proteus

Question 10

identifying salmonella enterica

Answer 10

G- rod, facultative anaerobe

lac- on macconkey
K/A w/ H2S on TSI

Question 11

salmonella e location

Answer 11

lower intestine in animals, acid tolerant and can survive stomach

Question 12

relevant serovars for humans of salmonella enterica

Answer 12

typhoid group (humans only)

non typhoid; enteridis, typhimurium, cholerasuis (zoonotic)

Question 13

sx of typhoid fever

Answer 13

gastroenteritis

slow progressing fever

profuse sweating

Question 14

spread of typhoid fever

Answer 14

asymptomatic carriers shed lots of infectious material

often spread via food

low infectious dose, starts as GI infection then disseminates

Question 15

tx for typhoid fever

Answer 15

antibiotics: cipro, ceftriaxone

(resistance to chloramphenicol, bactrim, ampicillin)

vaccines recommended for travelers

Question 16

non typhoid salmonella disease

Answer 16

larger infectious dose, GI sx and fever

antibiotics not recommended, rare disseminations

Question 17

shigella identification

Answer 17

G- non motile rod, facultative rod

lac-

Question 18

shigella colonization

Answer 18

lower intestine of humans, acid resistant so low infectious dose

Question 19

shigellosis transmission and sx

Answer 19

person to person only,

mild diarrhea to dysentrery

can lead to HUS

Question 20

shiga toxin

Answer 20

enterotoxic- blocks absorption and can cause HUS

A+B toxin, receptor on intestine, kidney, brain

antibiotics like cipro increase risk of HUS

Question 21

identifying campylobacter jejuni

Answer 21

G- motile cork screw rod

requires charcoal agar

Question 22

campylobacter jejuni infection

Answer 22

most common cause of diarrhea, usually from animal products

low infectious dose, lasts about a week but not tx w/ antibiotics

Question 23

listeria ID

Answer 23

G+ motile rod, grows at cold temps (refrigerated foods)

large host range

Question 24

listeria transmission

Answer 24

foodborne, mother to child

Question 25

listeria and pregnancy

Answer 25

can lead to miscarriage, stillbirth, preterm

neonates can aquire it- meningitis, encephalitis

Question 26

listeria tx

Answer 26

IV ampicillin and gentamicin 14-21 days

Question 27

3 subtypes enterotoxigenic bacteria

Answer 27

vibrio cholerae

ETEC

C diff toxin A and B

Question 28

ID V. cholerae

Answer 28

G-, motile curved rod, facultative anaerobe

Question 29

reservoir and transmission for cholerae

Answer 29

fresh, brackish, marine water

shells of fish

only humans infected, transmitted via water or food

Question 30

effect of ETEC toxin and cholera toxin

Answer 30

A+ B, activate adenylate cyclase

secretion of electrolytes out of cells which pulls water and causes diarrhea

Question 31

3 enteropathogenic bacteria

Answer 31

EPEC, Enterohemorrhagic E coli (EHEC- EPEC w/ shiga toxin), H pylori

Question 32

ID E coli

Answer 32

G- rod, facultative anaerobe

lac+ on macconkey

Question 33

E coli colonization

Answer 33

most are non pathogenic in colon, many pathogenic in animals and humans