Viral Inf of Gut & Nosocomial Diarrhea Flashcards Preview

Block 7 - GI > Viral Inf of Gut & Nosocomial Diarrhea > Flashcards

Flashcards in Viral Inf of Gut & Nosocomial Diarrhea Deck (26):
1

What are the major viral causes of gastroenteritis?

Rotavirus (peds > adults)
Norovirus (older children & adults > children)
Enteric adenovirus and astrovirus - mostly peds

2

What populations does rotavirus affect?

young children and elderly (nursing homes)
*can cause chronic diarrhea in immunocompromised

3

What are characteristics of rotavirus?

reovirus family
non-enveloped but resistant to drying, gastric acid, detergents, disinfectants - *allows survival in environment
RNA w 11 segments - can reassort

4

What is the structure of the rotavirus shell?

3 concentric shells
*outer - major antigens are surface glycoprotein VP7 and protease cleaved protein (VP4)

5

What are the different groups of rotavirus?

7 serogroups (A-G), A-C infectious
A - children
B, C - adults

6

What is the role of animals with rotavirus?

significant agricultural pathogen but transmission from animals to humans is rare

7

How does rotavirus infect?

*inf dose <10 virions
*fecal-oral spread
*daycare centers! (and nursing homes)
winter peak
infects at villous tip in small intestine

8

What are the dz manifestations of rotavirus?

incubation 1-3 days
vomiting is short-lived - *distinguishes from noro
watery diarrhea - dehydration common
lasts 3-4 days
stool leukocytes in small pop

9

What are the multiple mechanisms for diarrhea caused by rotavirus?

lytic growth destroys mature absorptive cells
immature cells take their place
NP4 is secretogogue - secretory diarrhea

10

How does immunity to rotavirus work?

transient - need repeated exposure
intestinal IgA and maternal antibody in breast milk are protective
serotype specific

11

What is the treatment for rotavirus?

no antivirals
symptomatic and supportive
rehydration - oral first

12

What are the criteria for IV rehydration in rotavirus?*

intractable vomiting
altered mental status (can't follow directions)
loss of >10% BW

13

What are characteristics of the norovirus?

calicivrus family - 2 of 4 genera affect humans
ss+RNA
non-enveloped, resistant to detergents, drying, etc.

14

How does norovirus infect?

inf dose is 10 virions
fecal-oral
epidemics common - hospital, *cruise ships

15

What are the dz manifestations of norovirus?

incubation 1-2 days
*VOMITING
less diarrhea than rotavirus
spontaneous improvement 2-3 days

16

How does immunity to norovirus work?

shortliveed, 4-6 mos
repeated exposure necessary
strain specific

17

What are the different causes of diarrhea in a hospital setting?

inf or non-inf
viral (rota, noro)
*antibiotic associated, not caused by c. dif
c. dif is most severe

18

What is c. dif?

strictly anaerobic
spore forming - spores can survive in environment
gram +rod

19

Where and how do lots of outbreaks of c. dif occur?

*nursing homes, hospitals
*carried on shoes, hands, clothing of healthcare workers
dz requires presence of toxin A & B

20

What is the most important risk factor for CDAD?

*previous or current antibiotic therapy

21

What are important clinical manifestations of c. dif?

*pseudomembranous colitis
*toxic megacolon
*elevated peripheral WBC
stool leukocytes and occult blood

22

What does the psuedomembrane consist of?

fibrin, PMNs, mucin, dead enterocytes

23

What is the treatment of c. dif colitis?

discontinue antibiotic
oral metronidazole (cheaper) and oral vanc
*vanc may be better for more severe dz
*IV vanc ineffective

24

When is oral vanc used as opposed to metronidazole for treating c. dif?

metronidazole fails or isn't tolerated
pregnancy or lactation

25

What is one way to treat relapsed or recurrent c. dif?

*stool transplant

26

What is the most important method of controlling c. dif inf?

*frequent washing of hands w soap and water