Module 15

Question 1

which of these are Gram + spore forming rods?

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

Answer 1

e - b & c

Question 2

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

Answer 2

E. coli

Question 3

what are the major pathogens of Gram - enteric rods

Answer 3

• Escherichia
• shigella
• salmonella
• vibrio

Question 4

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

Answer 4

• UTI
• invasive disease (septicemia, neonatal meningitis)

Question 5

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

Answer 5

E. coli

Question 6

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

Answer 6

gastroenteritis (diarrhea)

Question 7

what is the transmission of E. coli

Answer 7

• trauma
• immune suppression
• fecal-oral spread

Question 8

what are the virulence factors of E. coli

Answer 8

• LPS endotoxin (inflammation)
• enterotoxins

Question 9

what are examples of enterotoxins

Answer 9

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

Question 10

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

Answer 10

heat=liable toxin (LT)

Question 11

what is a small peptide that increases fluid secretion and diarrhea

Answer 11

heat-stable toxin (ST)

Question 12

what is the colonization and inflammation of a UTI

Answer 12

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

Question 13

what is the main cause of neonatal meningitis

Answer 13

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

Question 14

90% of vaginal normal flora E. coli express ___

Answer 14

capsule

Question 15

how does systemic inflammation or septic shock occur

Answer 15

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

Question 16

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

Answer 16

shigella

Question 17

___ causes classical bacterial dysentery

Answer 17

S. dysenteriae

Question 18

T/F shigella involves intracellular growth

Answer 18

true

Question 19

what is a virulence factor of shigella

Answer 19

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

Question 20

what population is bacterial dysentery most common in

Answer 20

pediatric

Question 21

what is shigella’s exotosin

Answer 21

shiga toxin

Question 22

what does shiga toxin cause

Answer 22

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

Question 23

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

Answer 23

bacterial dysentery

Question 24

what are signs and symptoms of shigella

Answer 24

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

Question 25

what is the primary reservoir of salmonella

Answer 25

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

Question 26

how do humans become infected with salmonella

Answer 26

ingestion of contaminated food or water or feces from infected animals

Question 27

what are the 2 forms of disease that salmonella can cause

Answer 27

- gastroenteritis - typhoid fever

Question 28

what specific bacteria causes gastroenteritis

Answer 28

s. typhimurium

Question 29

what specific bacteria causes typhoid fever

Answer 29

s. typhi

Question 30

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

Answer 30

intracellular, intestinal epithelium

Question 31

what is found only in S. typhi

Answer 31

Vi capsule

Question 32

what does S. typhi lack

Answer 32

exotoxins/enterotoxins

Question 33

what are the 2 current typhoid fever vaccines

Answer 33

- purified Vi capsule polysaccharide - live attenuated Ty 21a strain

Question 34

what are the visible characteristics of vibrio cholera

Answer 34

curved, Gram - rods with single polar flagella

Question 35

what is the preferred environment of vibrio

Answer 35

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

Question 36

what is the exotoxin of V. cholerae

Answer 36

cholera enterotoxin

Question 37

what does cholera enterotoxin do

Answer 37

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

Question 38

what are the clinical manifestations of cholera

Answer 38

rice water stool, dehydration, electrolyte imbalance caused by colonization of mucosal surface of the upper small intestine

Question 39

what is the treatment for cholera

Answer 39

fluid replacement

Question 40

what is the recent cholera vaccine

Answer 40

Vaxchora

Question 41

how does Vaxchora work

Answer 41

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

Question 42

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

Answer 42

a - yes its a live strain of vibrio

Question 43

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

Answer 43

d - all of these

Question 44

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

Answer 44

e - all of these are E. coli toxins