Bacteria (Part III)

Question 1

how can the enterobacteriaceae be largely separated?

Answer 1

into organisms that cause gastrointestinal disease and those that cause nosocomial infections

Question 2

what are the enterobacteriaceae organisms that cause gastrointestinal disease?

Answer 2

escherichia coli, shigella, salmonella, and yersinia enterocolitica

Question 3

what are the enterobacteriaceae organisms that cause nosocomial infections?

Answer 3

proteus mirabilis, klebsiella pneumoniae, enterobacteria, serratia

Question 4

What are 5 examples of lactose fermenters?

Answer 4

E. coli and many nosocomial enterobacteriaceae (Klebsiella, enterobacter, citrobacter, and serratia)

Question 5

what do lactose fermenters create on the agar plate?

Answer 5

they create a vibrant pink color change on MacConkey agar and appear dark black with a metallic sheen on EMB agar

Question 6

what is escherichia coli?

Answer 6

a gram negative rod, lactose fermenter, normal flora of GI tract; a protypical enteric bacteria of the enterobacteriaceae family

Question 7

how does E. coli pick up virulence factors?

Answer 7

through plasmids either through horizontal gene transfer or via bacteriophages

Question 8

what is the most common cause of urinary tract infection?

Answer 8

E. coli

Question 9

What diseases can E. coli cause? (4)

Answer 9

1) diarrhea 2) meningitis (especially neonatal) 3) urinary tract infection 4) PNA

Question 10

what virulence factor does E. coli have?

Answer 10

pili

Question 11

What causes enterotoxigenic E. coli?

Answer 11

consumption of fecally contaminated food or water; it is the most common cause of so called traveler’s diarrhea

Question 12

what are the high risk areas of acquiring enterotoxiogenic E. coli?

Answer 12

mexico, south america, africa, the middle east, and asia

Question 13

what does enterotoxiogenic E. coli cause?

Answer 13

watery diarrhea

Question 14

what are the toxins released from enterotoxiogenic E. coli that cause watery diarrhea?

Answer 14

Heat labile (LT) and heat stabile (ST) toxins

Question 15

how do the LT and ST toxins released by enterotoxiogenic E. coli cause watery diarrhea?

Answer 15

they cause an osmotic pull of water out of cells by causing failure of reabsorption of ions (Na or Cl) or secretion of ions (Cl or HCO3)

Question 16

what virulence factor does enteroinvasive E. coli have?

Answer 16

a virulence plasmid which allows it to invade the bowel wall–> the result is bloody diarrhea

Question 17

what strain of E. coli has been known to contaminate a wide variety of foods including undercooked meat and spinach as well as lettuce?

Answer 17

enterohemorrhagic E. coli

Question 18

what toxin does enterohemorrhagic E coli produce? (EHEC)

Answer 18

shiga-like toxin 1 or 2

Question 19

what is the effect of shiga-like toxin 1 or 2?

Answer 19

it causes cell death through ribosomal inhibition. The result is bloody diarrhea

Question 20

What is the subtype of enterohemorrhagic E. coli?

Answer 20

E. coli 0157

Question 21

what is the effect of E. coli 0157?

Answer 21

it causes hemolytic uremic syndrome

Question 22

what is hemolytic uremic syndrome?

Answer 22

a disease characterized by anemia, thrombocytopenia, and kidney damage

Question 23

what does E. coli 0157 produce?

Answer 23

a specific toxin- Stx2 toxin- which can cause endothelial damage to small blood vessels

Question 24

what does damage to endothelial cells caused by Stx2 cause?

Answer 24

microthrombi–> ultimately causes thrombocytopenia and anemia; the Stx2 toxin also causes kidney damage

Question 25

what is shigella?

Answer 25

a gram negative rod, non-motile, always pathogenic

Question 26

how is shigella transmitted?

Answer 26

through fecal oral transmission

Question 27

where are shigella outbreaks common?

Answer 27

in preschool, daycare centers, nursing homes

Question 28

what is the action of shigella?

Answer 28

it invades the intestine producing high fever with bloody diarrhea and abdominal cramps

Question 29

what are the four species of shigella?

Answer 29

S. sonnei, S. dysenteriae, S. flexneri, and S. boydii

Question 30

what is the most common species of Shigella in the US?

Answer 30

S. sonnei

Question 31

which species of shigella is the most virulent and why?

Answer 31

Shigella dysenteriae is the most virulent in that strains of it produce a shiga toxin that causes more widespread cell death by inhibiting protein synthesis at the 60 S ribosomal unit

Question 32

What is Salmonella?

Answer 32

a gram negative rod, motile, encapsulated

Question 33

how does salmonella spread?

Answer 33

fecal-oral transmission- unwashed contaminated food like chicken eggs or spinach

Question 34

what is salmonella typhi?

Answer 34

an exclusively human pathogen

Question 35

what is salmonella typhi associated with?

Answer 35

it can develop chronic carriage in the gallbladder; it is associated with gallbladder adenocarcinoma

Question 36

what is associated with non-typhoidal salmonella outbreaks?

Answer 36

zootonic reservoir- handling of pets such as turtles or hedgehogs

Question 37

What are the diseases associated with Salmonella?

Answer 37

typhoid fever, sepsis/bacteremia, gastroenteritis/diarrhea

Question 38

what specifically causes typhoid fever?

Answer 38

salmonella typhi

Question 39

what is the incubation period for typhoid fever?

Answer 39

7-14 day incubation period

Question 40

what type of fever is associated with typhoid fever?

Answer 40

a "stepwise fever"- rises during the day, drops each morning, troughs and peaks over time

Question 41

what are the symptoms/presentations of typhoid fever?

Answer 41

diffuse and colicky right upper quadrant abdominal pain, headache, malaise, hepatosplenomegaly, delirium "typhoid encephalopathy", fever peaks (104 F); development of "rose spots"= bacterial embolli; overwhelming toxemia can lead to death

Question 42

where can chronic carriage of Salmonella typhi occur?

Answer 42

in the gallbladder

Question 43

what diseases can the non-typhi salmonella cause?

Answer 43

localized infection of the bone, brain, and lung

Question 44

who is at risk for salmonella poisoning and why?

Answer 44

salmonella species are encapsulated so those without a spleen are more at risk for infection

Question 45

what can non-typhoidal salmonella species cause?

Answer 45

febrile watery diarrhea with or without some associated trace blood