GI 5

Question 1

4 genera of norwalk virus

Answer 1

NOROVIRUS, SAPOVIRUS, lagovirus, vesivirus

Question 2

feature of norwalk virus

Answer 2

• naked, + ssRNA

- amorphous surface with feathery ragged outline

Question 3

causes 66% of gastroenteritis outbreaks in long term facilities

Answer 3

sapovirus (family of calciviridae)

Question 4

types of patients you see sapovirus

Answer 4

children and adults (elderly)

Question 5

sapovirus is common in older children and adults. why is it becoming popular in children less than 5 years

Answer 5

because of vaccination to rotavirus

Question 6

what time of the year is norovirus common

Answer 6

winter

Question 7

transmission of norwalk virus/norovirus

Answer 7

primarily fecal oral route

but can be air and food borne

Question 8

food is norovirus commonly seen in

Answer 8

raw shellfish

Question 9

pathogenesis of norovirus

Answer 9

virus multiplies in the SI –> produces transient lesion of the mucosa –> spares the large intestine –> shed in feces

Question 10

importance of norovirus sparing the large intestine

Answer 10

there is NO FECAL LEUKOCYTES

Question 11

clinical manifestation of norovirus: include incubation period, duration, and symptoms

Answer 11

• incubation - it is mild and brief so 24-48 hrs
• duration: lasts 24-60 hours
• abdominal cramps, myalgias, malaise, headache, nausea, low grade fever & 1-2 days diarrhea
• fatalities are rare

Question 12

how do you diagnose norovirus

Answer 12

• mean duration of 12-60hrs
• mean incubation is 24-48hrs
• greater than 50% of people with vomiting
• no bacterial agent previously found

Question 13

how do you detect norovirus

Answer 13

not sensitive so must difficult to culture

-virus peaks in stool at about day 2-5 so you can do RT-qPCR assay

Question 14

where do you commonly see norovirus outbreaks

Answer 14

cruise ships

Question 15

how do you treat norovirus

Answer 15

• Ligolyte

- 2 doses of IM vaccine taken 3 weeks apart

Question 16

describe adenovirus

Answer 16

• icosahedral
• naked ds DNA
• 12 vertices pentons with fibers on the end

Question 17

two serotypes of adenovirus

Answer 17

40 and 41 (Group F)

Question 18

pathogenesis of adenovirus

Answer 18

• main target is the respiratory tract but infects epithelial cells of pharynx, conjuctiva, SI, and other organs
• if in SI, it will replicate and present in the stool

Question 19

symptoms of adenovirus

Answer 19

diarrhea with or without vomiting

Question 20

features of astrovirus

Answer 20

small, naked +ssRNA that has smooth or slight indented outer shell

Question 21

when are people infected with astrovirus

Answer 21

throughout the year but peak in the winter

Question 22

feature of Hep A

Answer 22

icosahedra, naked +ssRNA

Question 23

how is Hep A virus spread

Answer 23

fecal oral route, person to person, poor sanitation, and overcrowding

Question 24

Hep A is the common cause of what condition and what are the first symptoms

Answer 24

acute hepatitis
nausea, vomiting, and fever
jaundice comes later on and does not subside until all the other symptoms are gone

Question 25

features of Hep E

Answer 25

naked, symmetrical +ssRNA

Question 26

where do you find Hep E and what is its incubation period

Answer 26

found in Indian subcontinent | 6 weeks which is longer than Hep A

Question 27

what are inflammatory diarrhea

Answer 27

``` – Bacterial • Shigella spp. • E. coli (EIEC) • Salmonella Serotypes • Campylobacter spp. • Yersinia spp. • V. parahaemolyticus & V. vulnificus • EAEC & STEC (EHEC) (Non invasive organisms - cytotoxin) ``` – Parasitic • Entamoeba histolytica • Balantidium coli

Question 28

what is the symptomology of inflammatory diarrhea

Answer 28

bloody diarrhea

Question 29

how do you get the microbes associated with inflammatory diarrhea and what are the type of toxins released

Answer 29

food borne infection | release enterotoxin and cytotoxins

Question 30

what are the 4 groups of O antigen of shigella and classify them according to their severity

Answer 30

shigella dysenteriae (most severe) shigella flexneri shigella boydii shigella sonnei (mildest form) --> water diarrhea instead of bloody diarrhea

Question 31

what is the virulence factors of shigella

Answer 31

- endotoxin (O antigen) - exotoxin: enterotoxin that act as neurotoxin - NAD glycohydrolase

Question 32

what does the enterotoxin and NAD glycohydrolase in shigella do

Answer 32

- enterotoxin which acts as a neurotoxin causes meningismus and coma and ulceration - NAD glycohydrolase destroys all NAD in human cells hence shutting down metabolism and then cell death

Question 33

what are the clinical manifestation of shigella sonnei and flexneri

Answer 33

- flexneri: severe abdominal pain and dysentery | - sonnei: vomiting and watery diarrhea common

Question 34

pathogenesis of shigellosis

Answer 34

- ingest small amount which invades epithelial and M cells in large intestine via invasive induce endocytosis - multiplies in the cytoplasm - then spreads to adjacent epithelial cells by actin polymerization --> cell destruction via apoptosis

Question 35

what is bacillary dysentery

Answer 35

shigella dysenteriae type 1 (shiga bacillus)

Question 36

what is so important about shigella dysenteriae type 1 (shiga bacillus)

Answer 36

the only species to produce the shiga toxin --> which is a cytotoxin that inhibits protein synthesis leading to cell death

Question 37

what does the shiga toxin act as?

Answer 37

enterotoxin --> produces diarrhea exotoxin --> inhibits sugar and AA absorption in SI neurotoxin --> affects CNS

Question 38

common population that you see the shigellas in

Answer 38

shigella sonnei - children less than 5 years in day care shigella flexneri - men who have sex with other men shigella boydii - rare

Question 39

pathogenesis of shigella

Answer 39

transmitted the fecal oral route: sanitation break downs (4 Fs - fingers, food, flies, feces)

Question 40

treatment of shigella

Answer 40

antibiotics tetracycline - most common chloramphenicol ampicillin

Question 41

how do you diagnose shigella

Answer 41

take sample of stool or water or food | use MacConkey's agar or S-S agar (salmonella-shigella agar)

Question 42

what would you see on the S-S agar for shigella -- why?

Answer 42

it will grow as colorless or pale due to no lactase fermentation shigella is non motile, gram negative, no fermentation lactose, no utilization of citric acid, no H2S production (except S. flexnieri), no gas from glucose