Shigella and Salmonella Flashcards

Presentation Cell Biology Epidemiology Transmission i. innoculum Incubation Period Pathogenesis Treatment Prevention I. Salmonella A S. Typhi B. S. cholerasuis C. S. Enteriditis/ tymphimurium II. Shigella A. most are pretty similar

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1
Q

shigella ___ is the most common species in the developing world

A

shigella dysenteriae

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2
Q

shigella _____ is the most common form in the US

A

shigella sonnei

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3
Q

Shigelli ____ is the most common kind in India

A

shigella boydii

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4
Q

shigella ____ also common in developing countries

A

shigella flexneri

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5
Q

shigella: cell bio

A

gram +

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6
Q

shigella: presentation

A

fever and diarrhea with bloody stool and tenesmus

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7
Q

tenesmus

A

the feeling of needing to constantly pass stool

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8
Q

shigella: bacteremia

A

no/ rare

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9
Q

shigellia: incubation

A

1-4 days

persists for 1-4 week after recovery

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10
Q

shigella: innoculum

A

100 bugs, acid tolerant

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11
Q

shigellla: vaccine?

A

no

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12
Q

shigella: treatment

A

fluid and electrolyte replacement

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13
Q

shigella: diagnosis
a. motility
b. gas production?
c. h2S

A
Stool Analysis
1. non motile
2 non gas producing
3. no H2S
4. PMNs= invasive disease
*compare to salmonella
* indole and ureas negative
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14
Q

indole test

A

ability of bacteria to convert tryptophan to pyruvate and indole, a metabolite

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15
Q

Kilger Iron Agar

A

demonstrates sugar fermentation, gas production, and H2S production

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16
Q

shigella: prevention

A

sanitation

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17
Q

shiga toxin

A

an exotoxin with two subunits A and B

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18
Q

shiga toxin subunit B

A

binds to intestinal cells

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19
Q

shiga toxin subunit A

A

binds to 60 S ribosomal RNA to prevent protein synthesis

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20
Q

shigella: path, T3SS

A

allows macrophage infiltration and escape

21
Q

shigella, path, fever

A

IL-1 and TNF from monocytic cells

22
Q

shigella, path: ulceration

A

Shiga toxin

23
Q

S Typhi: incubation

A

7-14 days

24
Q

S Typhi: presentation

A
  1. Fever
  2. bradycardia
  3. Rose spot (skin rash)
  4. leukopenia
  5. enlarge liver and spleen
25
Q

S. Typhi: Vi antigen

A

may allow survival inside phagocytic vesicles

26
Q

S. Typhi: SPI-1

A

salmonella pathogenecity island

encodes T3SS

27
Q

Type III secretion systems: SPI-2

A

salmonella pathogenecity island

encodes endotoxin

28
Q

T3SS(Type II secretion systems)

A

a specialized form of secretion– an injection needle allows transfer from a bacterial cytoplasm to host cytoplasm

29
Q

S. Typhi: Treatment

A

Fluoroquinolones
Cephalosporins
Chronic Carrier: Ampicillin, Ciprofloxacin, cholecystectomy

30
Q

S. Typhi: Diagnosis

A

Week 1; stool culture
Week 2: blood culture
Week 3: stool culture (gall bladder)

31
Q

S. Typhi: Vaccines

A
  1. Typ21a (live attenuated)

2. VICPS (capsular polysaccharide)

32
Q

S. Typhi: Typhoid Fever Pathogenesis

A

rehearse steps

  1. survives stomach
  2. adhesins attach to peithelium
  3. endocytosis
  4. ingestion by macrophages
  5. Vi allows survival inside vacuoles
  6. kill macrophages, diseeminate via thoracic duct to blood, liver, spleen, gall bladder
  7. reinvasion via gall bladder
  8. GI bleeds and diarrhea
33
Q

path: endotoxic shock

A

the Lipid A component of endotoxin triggers cytokines

IL-1, IL-6, and TNF-α

34
Q

path: T3SS

A

type 3 secretion system

35
Q

S. Typhi: prevention

A

Water Sanitation
Pasteurization
2 Vaccines

36
Q

S. cholerasuis: transmission

A

swine

37
Q

S. cholerasuis: incubation

A

6-72 hours

38
Q

S. cholerasuis: presentation

A

gastroenteritis followed by bacteremia and fever

39
Q

S. cholerasuis: epi

A

rare

young age, malaria, immune dysfunciton, AIDS, ‘roids, immunsuppression, sickle cell anemia

40
Q

S. Typhinmurium and Enteriditis: presentation

A

headache, chills, abdominal pain, vomitting, diarrhea, then fever

41
Q

S. Typhinmurium and Enteriditis: duration

A

1-4 days

42
Q

S. Typhinmurium and Enteriditis: incubation

A

8-48 hours after consumption

43
Q

S. Typhinmurium and Enteriditis: diagnosis

A
  1. fecal culture: salmonella traits

2. PCR; O and H antigen

44
Q

S. Typhinmurium and Enteriditis: treatment

A

self limting
fluid and electrolyte replacement
antibiotics if necessary

45
Q

S. Typhinmurium and Enteriditis: path

A
  1. LPS
  2. T3SS
  3. extracellular toxins
46
Q

S. Typhinmurium and Enteriditis: Sources

A

poultry, pork, dog food, eggs
contamination of egg shells
fruits and vegetables
reptiles

47
Q

S. Typhinmurium and Enteriditis: disease

A

non-tyhpoidal bacteremia associated with a weakened immune system

48
Q

S. Typhinmurium and Enteritidis: pathogenesis

A
  1. LPS release during epithelial cell invasion
  2. T3SS mediated invasion of macrophages
  3. extracelullar microbes produce toxins (pertussis like) that promote inflammation