Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

M1 Micro Quiz 2 > Salmonella and Shigella > Flashcards

Salmonella and Shigella Flashcards

1
Q

what is a bacterial strain?

A

a population of organisms within a species that descends from a single organism

  • evolve by mutation and/or by acquiring additional genes by horizontal gene transfer
  • surface components often vary
  • sub population of a species
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is a bacterial serotype?

A

a strain that is differentiated by serological means

based on antibody recognition of antigens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are O antigens?

A

the polysaccharide component of LPS

Side chains vary to aid in immunevasion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the H antigen?

A

the flagellar antigen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the K antigen?

A

polysaccharide capsule component

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the possible clinical syndromes of salmonellosis? (3)

A

1) Typhoid/enteric fever
2) septicemias
3) acute gastroenteritis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the genus of salmonella? what type of bacteria is it? (gram, shape)

A

member of Enterobacteriaciae

gram-negative rod

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

where is salmonella typhi often found?
what disease does it cause?
what is it’s incubation period?

A

common in developing world
causes typhoid fever
Incubation period: 7-14 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what species does S. Typhi infect?

A

-only infects humans via food/water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does S. typhi survive phagocytic vacuoles?

A

enabled by Vi antigen of polysaccharide capsule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

how are Salmonella typhi pathogenicity islands acquired? what do they consist of?

A

acquired through horizontal gene transfer
G+C content, phage/transposon sequences, non-native adjacent sequences
SPI-1 and SPI-2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what does the SPI-1 (Salmonella pathogenicity island 1) encode for?

A

encodes genes for invasion

Type 3 secretion system (T3SS)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the T3SS (type 3 secretion system)?

A

a specialized form of secretion wherein a protein moves across the bacterial cytoplasmic and outer membrane AND across the host cell membrane through an injection needle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Salmonella T3SS delivers?

A

toxins that induce membrane ruffling by stimulating actin polymerization, and endocytosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what does SPI-2 (salmonella pathogenicity island 2) encode for?

A

encodes genes for intracellular survival

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is endotoxin a component of? what does it cause?

A

lipid A component of LPS

causes fever and shock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

how would you diagnose S. typhi? (at 1 week, 2-3 weeks, after 3 weeks)

A

Week 1: subclinical, positive stool culture
Weeks 2-3: symptomatic, positive blood cultures
After week 3: stool culture positive again following gall bladder colonization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

how do you treat S. typhi? (acute, chronic)

A

Acute: Fluoroquinolones, 3rd generation cephalosporin
Chronic carrier:
1) Ampicillin/Ciprofloxacin
2)cholecystectomy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how can S. typhi be prevented?

A
  • control of water and sewage (humans only host)
  • food safety and pasteurization
  • 2 vaccines: oral attenuated and Vi capsular polysaccharide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

are there vaccines for S. typhi? if so, what are they and what type?

A

Ty21a: live attenuated
ViCPS: capsular polysaccharide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

how is Salmonella cholerasuis spread? how many organisms are required for infection?

A

oral ingestion of contaminated swine

infectious dose: 1000 organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

where are Salmonella enteriditis and Salmonella typhimurium most common? what are the normal symptoms? what tests could be used to detect it?

A

most common Salmonella infection in U.S.
diarrheal disease mostly confined to GI tract
infrequent positive blood cultures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what are the sources of S. enteriditis and S. typhimurium?

A

poultry, pork, dog food, eggs (eggs most common, inside and outside shell)
contaminated fruits/vegetables
turtles and other reptile pets
sandbox

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is the incubation period of S. enteriditis and S. typhimurium? what are the clinical symptoms? how long do they last?

A

4-48hr incubation
sudden onset of headache, chills, abdominal pain, vomiting, diarrhea, fever
lasts 1-4 days

25
Q

describe the pathogenesis of S. enteriditis and S. typhimurium.

A

LPS release during invasion of epithelial cells of intestine causes many symptoms
T3SS mediates invasion of epithelial cells
extracellular cells produce toxins (including pertussis-like toxin) that promote inflammation and secretion

26
Q

how are S. enteriditis and S. typhimurium treated?

A

mostly self-limiting
fluid and electrolyte replacement
pts with predisposing conditions get antibiotics but resistance is possible

27
Q

Salmonella diagnosis (What does it ferment? Is it motile? Oxidase, urease, nitrate, indole?)

A 
Isolation in feces or blood
Ferments glucose, does not ferment lactose
Motile
oxidase negative
can reduce nitrate
Urease negative
Indole negative
Produce H2S
28
Q

what is the genus of Shigella? what type of bacteria is it (gram, shape)?

A

Enterobacteriaciae

Gram-negative rods

29
Q

what is the most common Shigella species in U.S.?

A

Shigella sonnei

30
Q

what is the most common Shigella species in developing world?

A

Shigella dysenteriae

31
Q

what are the clinical symptoms of Shigella?

A

Fever (due to LPS), diarrhea and abdominal cramps (due to Shiga toxin)
Bloody, mucous diarrhea
Usually self-limiting
Bacteremia rare

32
Q

describe the pathogenesis of Shigella. (how does it infect and spread?)

A

Invade intestinal cells in terminal ileum and colon

Uptake by macrophages followed by escape and cell-to-cell spread

33
Q

describe the virulence of Shigella? (ie how does it create disease)

A

T3SS-secreted Shigella protein induces macrophage uptake and escape
Induces apoptosis of macrophages and release of IL-1 and TNF
Shiga toxin causes intestinal ulceration
Diarrhea due to fluid malabsorption

34
Q

what is Shiga toxin? what are the subunits? what does it do?

A

Exotoxin produced by Shigella
2 subunits: A & B
causes intestinal ulceration
May lead to apoptosis of mucosal cells

35
Q

what does the Shiga toxin subunit A do?

A

interferes with function of 60S ribosomal RNA inhibiting protein synthesis

36
Q

what does the Shiga toxin subunit B do?

A

binds to receptor on intestinal cells

37
Q

how is Shigella diagnosed?

A

clinical Sx NOT diagnostic
Isolation of microorganisms from feces
detection of PMNs in stool indicates invasive disease

38
Q

Shigella important diagnostic traits (Ferments? Motile? Antigens? Indole, Urease?)

A 
Ferments glucose (no gas), does not ferment lactose
Nonmotile
Contains O antigens only (no H)
Indole negative
Urease negative
39
Q

how is Shigella treated?

A

fluid and electrolyte replacement

antibiotics in severe cases, resistance is increasing

40
Q

What is the incubation period for Salmonella typhi? What are the diagnostic symptoms and clinical syndrome?

A

Incubation period: 7-14 days
Dx Sx: Episodic fever, bradycardia, skin rash (Rose spot)
Bacteremic phase: leukopenia, hepatosplenomegaly
late GI phase: intestinal hemorrhage or perforation

41
Q

Word association: Rose Spots

A

Salmonella typhi

42
Q

how is Shigella prevented? is there a vaccine? if so, what type?

A

Improve sanitation (humans are only host)
No effective vaccine
Recombinant O-antigen vaccine conjugated to Shiga toxin is promising vaccine candidate

43
Q

How is S. Typhi diagnosed? (what symptoms would you see?)

A
  • Episodic fever
  • bradycardia
  • skin rash (Rose spot)
44
Q

describe the pathogenesis of S. Typhi. how does it enter cells and the body? what symptoms does it cause?

A
  • resistant to stomach acid
  • adhesins promote attachment to intestinal epithelium
  • induce bacterially-mediated endocytosis into epithelial cells
  • ingested by macrophage, survives inside phagocytic vacuoles and lysosome
  • kills macrophage and disseminate via thoracic duct
  • causes fever and shock when in blood stream
  • reinvasion of GI tract from gall bladder
45
Q

what symptoms occur during the bacteremic phase of S. Typhi?

A
  • leukopenia

- hepatosplenomegaly

46
Q

what symptoms occur during the late GI phase of S. Typhi?

A

intestinal hemorrhage or perforation

47
Q

what disease does shigella cause?

A

causes dysentery (shigellosis)

48
Q

how is shigella spread?

A

spread by Food, Fingers, Feces, and Flies (4Fs)

49
Q

who is most susceptible to shigella?

A

Children under 10 more susceptible

50
Q

what are the reservoirs of shigella?

A

No animal reservoir

51
Q

how long can shigella be detected in feces after recovery?

A

Organisms detectable in feces 1-4 wks after recovery

52
Q

what is the incubation period of Salmonella cholerasuis?

A

short incubation: 6-72hrs

53
Q

what are the symptoms of Salmonella cholerasuis?

A

high fever and bacteremia with gastroenteritis

microabsesses

54
Q

how many shigella organisms are required to infect?

A

Low inoculum (100 bugs)

55
Q

how does shigella respond to acid?

A

acid tolerant

56
Q

how long is the incubation period of shigella?

A

1-4 day incubation

57
Q

How do strains arise?

A

Mutation and/or acquiring additional genes

58
Q

What is a serotype? What is stereotyping?

A

Group of organisms that are recognized by the same antibodies
Useing specific antisera that contains antibodies to specific bacterial antigens
Can be different strains within a serotypes and different strains can have the same serotype - the serotype is specifically only the group of bacteria for which the same antibody reacts

M1 Micro Quiz 2 (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions