Module 15 Flashcards

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1
Q

which of these are Gram + spore forming rods?

a - corynebacterium diphtheria
b - bacillus anthracis
c - clostridium perfringens
d - listeria monocytogenes
e - b & c

A

e - b & c

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2
Q

what bacteria is a Gram - rod that is found in intestines of humans and animals and widely distributed on plants, in soil and water

A

E. coli

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3
Q

what are the major pathogens of Gram - enteric rods

A
  • Escherichia
  • shigella
  • salmonella
  • vibrio
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4
Q

what can be caused by normal flora strains of E. coli that escape from the intestinal tract and colonize other body sites

A
  • UTI
  • invasive disease (septicemia, neonatal meningitis)
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5
Q

what is in the normal intestinal flora and is the leading cause of both community-acquired and nosocomial infections

A

E. coli

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6
Q

what can be caused by “new” strains of E. coli that have acquired additional virulence factors

A

gastroenteritis (diarrhea)

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7
Q

what is the transmission of E. coli

A
  • trauma
  • immune suppression
  • fecal-oral spread
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8
Q

what are the virulence factors of E. coli

A
  • LPS endotoxin (inflammation)
  • enterotoxins
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9
Q

what are examples of enterotoxins

A
  • plasmid coded enterotoxins
  • heat-liable toxin (LT)
  • heat-stable toxin (ST)
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10
Q

what causes the activation of adenylate cyclase leading to fluid secretion and diarrhea and is related to the cholera toxin family

A

heat=liable toxin (LT)

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11
Q

what is a small peptide that increases fluid secretion and diarrhea

A

heat-stable toxin (ST)

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12
Q

what is the colonization and inflammation of a UTI

A
  • bladder (cystitis)
  • invade and replicate in epithelial cells
  • ascends to kidney (pyelonephritis)
  • spread to bloodstream
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13
Q

what is the main cause of neonatal meningitis

A

vaginal normal flora E. coli colonizes the infant at birth during passage through the birth canal

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14
Q

90% of vaginal normal flora E. coli express ___

A

capsule

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15
Q

how does systemic inflammation or septic shock occur

A

stimulated by large amounts of endotoxins in intestinal E. coli that crosses epithelial surfaces and invades the bloodstream of a patient with immune impairment or mechanical damage

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16
Q

what bacteria is closely related to E. coli but is NOT normal flora

A

shigella

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17
Q

___ causes classical bacterial dysentery

A

S. dysenteriae

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18
Q

T/F shigella involves intracellular growth

A

true

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19
Q

what is a virulence factor of shigella

A

plasmids that encode proteins for attachment / entry into intestinal epithelial cells

20
Q

what population is bacterial dysentery most common in

A

pediatric

21
Q

what is shigella’s exotosin

A

shiga toxin

22
Q

what does shiga toxin cause

A

transfer of lysogenic phage chromosome to E. coli making it lethal and inhibiting protein synthesis thus damaging endothelial cells in the intestinal mucosa and systemically in kidneys

23
Q

what is colonization of large intestines with invasion and replication within colonic epithelial cells causing erosion of the large intestine epithelia

A

bacterial dysentery

24
Q

what are signs and symptoms of shigella

A
  • cramps, painful straining, bloody mucoid discharge
  • large numbers of leukocytes & RBCs in stool
  • fever
25
Q

what is the primary reservoir of salmonella

A

intestinal tract of animals (birds, cattle, pet reptiles, etc.)

26
Q

how do humans become infected with salmonella

A

ingestion of contaminated food or water or feces from infected animals

27
Q

what are the 2 forms of disease that salmonella can cause

A
  • gastroenteritis
  • typhoid fever
28
Q

what specific bacteria causes gastroenteritis

A

s. typhimurium

29
Q

what specific bacteria causes typhoid fever

A

s. typhi

30
Q

salmonella has ___ survival and growth & remains only at the ___

A

intracellular, intestinal epithelium

31
Q

what is found only in S. typhi

A

Vi capsule

32
Q

what does S. typhi lack

A

exotoxins/enterotoxins

33
Q

what are the 2 current typhoid fever vaccines

A
  • purified Vi capsule polysaccharide
  • live attenuated Ty 21a strain
34
Q

what are the visible characteristics of vibrio cholera

A

curved, Gram - rods with single polar flagella

35
Q

what is the preferred environment of vibrio

A

surface waters worldwide that grow over wide ranges of temperatures with high pH

36
Q

what is the exotoxin of V. cholerae

A

cholera enterotoxin

37
Q

what does cholera enterotoxin do

A

chemically modifies adenylate cyclase and stimulates fluid secretion in intestinal epithelial cells

38
Q

what are the clinical manifestations of cholera

A

rice water stool, dehydration, electrolyte imbalance

caused by colonization of mucosal surface of the upper small intestine

39
Q

what is the treatment for cholera

A

fluid replacement

40
Q

what is the recent cholera vaccine

A

Vaxchora

41
Q

how does Vaxchora work

A

oral, live attenuated V. cholerae 01 with toxin lacking A subunit that triggers protective mucosal Ab to whole bacterium and to the toxin B subunit

42
Q

is there a vaccine for cholera?

a - yes its a live strain of vibrio
b - yes its a subunit of vibrio toxin
c - no not yet
d - yes its a closely related strain of salmonella

A

a - yes its a live strain of vibrio

43
Q

what is the Vi capsule that is important in Typhoid Fever?

a - capsule seen only on S. Typhi bacteria
b - important in using live Salmonella as a vaccine
c - it is antiphagocytic
d - all of these

A

d - all of these

44
Q

which is NOT a toxin E, coli can acquire by horizontal gene exchange and become dangerous?

a - shiga toxin
b - heat stable toxin
c - heat liable toxin
d - LPS endotoxin
e - all of these are E. coli toxins

A

e - all of these are E. coli toxins

45
Q
A