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AA Microbio Semifinal > IIA. Systemic Bacteriology | 9. Salmonella and Shigella > Flashcards

IIA. Systemic Bacteriology | 9. Salmonella and Shigella Flashcards

1
Q

I. Salmonella
1. What are the features of salmonella?

A
  • Gram-negative
  • motile rods, peritrich flagella
  • Non-spore forming
  • Facultative anaerobic
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2
Q

I. Salmonella
2. What are the optimal environment for Salmonella?

A
  • Salmonella grow at an optimum of 37oC
  • Optimum pH for growth of Salmonella is 6.5-7.5; may grow at a pH range of 4.5-9.0
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3
Q

I. Salmonella
3. what are the biochemical properties of salmonella?

A
  • H2S production
  • Lactose negative, Urease negative, Indol negative
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4
Q

I. Salmonella - Salmonella serology
4A. What is Salmonella serology based on?

A

Serogroups or serotypes based on O and H (flagella) antigens.

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5
Q

I. Salmonella - Salmonella serology
4B. What are the features of O antigens

A

O antigens are vary variable

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6
Q

I. Salmonella - Salmonella serology
4C. What are the features of H antigens

A

The H (flagella) antigens
* occur in two phases;
1 and 2 and only one phase is expressed at a given time

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7
Q

I. Salmonella
5. What are the salmonella virulence factors?

A
  • Endotoxin – may play a role in intracellular survival
  • Capsule (for S. typhi and some strains of S. paratyphi)
  • Adhesions – both fimbrial and non-fimbrial
  • Flagella – help bacteria to move through intestinal mucous
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8
Q

I. Salmonella
6. Which species of Salmonella have capsule as a virulence factor?

A

Capsule (for S. typhi and some strains of S. paratyphi)

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9
Q

I. Salmonella
7A. What is clinical significance of salmonella?

A
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10
Q

I. Salmonella
7B. What are the features of salmonellosis?

A
  • Salmonella multiply in the GI tract inducing a strong inflammatory response
  • > The inflammatory response prevents the spread beyond the GI tract and eventually kills the bacteria.
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11
Q

I. Salmonella
7C. What are the features of enteric fever?

A

Salmonella disseminate before they multiply to high enough levels to stimulate a strong inflammatory response.

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12
Q

I. Salmonella
8. What are important serotypes of salmonella?

A

S. Typhi and Paratyphi A, B, C

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13
Q

I. Salmonella
9. What are the features of zoonotic infections?

A
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14
Q

I. Salmonella
10. What are the serotypes responsible for salmonellosis?

A

caused by for e.g. S. Enteritidis, S. Typhimurium, S. Choleraesuis

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15
Q

I. Salmonella - serotypes responsible for salmonellosis
11. What is the source of infection of serotypes responsible for salmonellosis?

A

animal feces

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16
Q

I. Salmonella - serotypes responsible for salmonellosis
12. What is the transmission route of infection of serotypes responsible for salmonellosis?

A

route of transmission: consumption of food contaminated with human feces
* especially improperly cooked poultry, eggs
* symptoms usually start 18-24 hours after ingestion

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17
Q

I. Salmonella - serotypes responsible for salmonellosis
13. What is the disease caused by serotypes responsible for salmonellosis?

A
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18
Q

I. Salmonella - serotypes responsible for salmonellosis
14. How do we diagnose serotypes responsible for salmonellosis?

A
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19
Q

I. Salmonella - serotypes responsible for salmonellosis
15. What is the treatment for salmonellosis?

A
  • AB treatment is not needed
  • supportive treatment (rehydration mainly)
  • in invasive / systemic cases might consider ampcillin, fluoroquinolons, ceftriaxon
21
Q

I. Salmonella - enteric fever
16. What are serotypes responsible for enteric fever?

A

Caused by S. Typhi, S. Paratyphi A, B, C

21
Q

I. Salmonella - enteric fever (S. Typhi, S. Paratyphi A, B, C)
17. What is the source of infection of enteric fever?

A

infected human feces

22
Q

I. Salmonella - enteric fever (S. Typhi, S. Paratyphi A, B, C)
18. What is the transmission route of infection of enteric fever?

A

consumption of food contaminated with infected human feces

23
Q

I. Salmonella - enteric fever (S. Typhi, S. Paratyphi A, B, C)
18. How does enteric fever infect?

A

enteric fever (invasive infection!)
- small intestine invasion
→ macrophages (Peyer-patches)
→ mesenteric lymphnodes
→ primary bacteriaemia (blood stream)
→ hepatic Kupffer cells
→ secondary bacteriaemia

24
Q

I. Salmonella - enteric fever (S. Typhi, S. Paratyphi A, B, C)
19. What are the symptoms of enteric fever?

A
  • high fever
  • bradycardia, rash
  • “brain fog” (confusion)
  • hepatosplenomegaly
  • Peyer-patch perforation (blood might appear in stool)
25
Q

I. Salmonella - enteric fever (S. Typhi, S. Paratyphi A, B, C)
20A. How do we diagnose enteric fever?

A
  • diagnosis: based on clinical signs and symptoms
    1. Sampling
    2. Laboratory
26
Q

I. Salmonella - enteric fever (S. Typhi, S. Paratyphi A, B, C)
20B. How do we diagnose enteric fever based on sampling?

A

stool, bile, blood culture, blood (for serology)

27
Q

I. Salmonella - enteric fever (S. Typhi, S. Paratyphi A, B, C)
20C1. How do we diagnose enteric fever based on laboratory?

A

Cultivation, but it is not enough (all are S. enterica, but the serotype does matter!)
- serotyping→ agglutination
- indirect confirmation: mixing patient’s serum with known Salmonella Typhi bacteria in a test tube → agglutination = confirms that the patient has antibodies against S. Typhi (Gruber-Widal tube agglutination)

28
Q

I. Salmonella - enteric fever (S. Typhi, S. Paratyphi A, B, C)
20C2. How do we perform indirect confirmation of enteric fever based on laboratory diagnose?

A

consumption of food contaminated with infected human feces

29
Q

I. Salmonella - enteric fever (S. Typhi, S. Paratyphi A, B, C)
21. What is the empirical treatment for enteric fever?

A
  • beta-lactams (aminopenicillins, cephalosporins)
  • fluoroquinolons
  • trimetophrim-sulfamethoxazol
30
Q

I. Salmonella - enteric fever (S. Typhi, S. Paratyphi A, B, C)
22. How do we prevent enteric fever?

A

Vaccination (pl. Typhim Vi: capsular vaccine)
- recommended before travelling to certain destinations
- mandatory in certain professions ( laboratory workers, wastewater technicians)

31
Q

I. Salmonella
23A. What are the agar plates suitable for Salmonella culturing?

A
  1. Bismuth-sulphite agar: H2S-production → black colonies
  2. brillantgreen ager
  3. deoxycholate-citrate agar (DC)
  4. Xylose-lysine deoxycholate agar (XLD): H2S-production → black colonies
  5. Hektoen-agar
32
Q

I. Salmonella
23B. What are the features of Brillant-green culture media?

A
  • Brillant green – for selection lactose, dextrose, saccharose Andrade indicator
    (acidic pH -> - Salmonella lactose neg.– no colour - E. coli lactose+ - red)
33
Q

I. Salmonella
23C. What are the features of Bismuth-sulphite media?

A

brillant green – for selection bismuth salt + sodium sulphite -> Salmonella H2S production
=> Bismuth sulphide (black)

34
Q

I. Salmonella
24. What are the bacteria that cause typhoid and parathyoid fever?

A
35
Q

II. Shigella
1. What are the features of Shigella?

A
  • Gram Negative (-) rod, enterobacteriaceae, non-lactose fermenter
  • Facultative anaerobic
  • Non-motile
  • Grows green colonies on hektoin agar
  • Acid resistant (only a few organisms required to start an infection
36
Q

II. Shigella
2. What is the optimal environment for Shigella?

A
  • pH 6.4 to 7.8
  • Temperature 10-40 (optimal temperature 37oC)
37
Q

II. Shigella
3. List the pieces of Shigella genus

A
38
Q

II. Shigella
4. What is the source of infection of shigella?

A

: human feces (feco-oral transmission)

39
Q

II. Shigella
5A. What is the disease caused by shigella?

A

dysentery

40
Q

II. Shigella
5B. What is the pathomechanism of Shigella?

A
  • bacterium infects the intestinal epithelial cells through M-cells
  • leads to inflammation and ulceration in the bowels
    (* might heal spontaneously)
40
Q

II. Shigella
5C. What is the diagnosis of Shigella?

A

dysentery

41
Q

II. Shigella
5D. What is the empirical therapy of Shigella?

A
  • rehydration
  • Antibiotics: beta-lactams (penicillins, cephalosporins); luoroquinolons; trimetophrim-sulfamethoxazol
42
Q

II. Shigella
6. What do S. dysenteriae do?

A

Dysenteriae produces Shiga-toxin
- capillary entdothelium damage → blood clot formation → RBC damage
→ haemolysis (haemolytic uraemic syndrome - HUS)

43
Q

II. Shigella
7A. What are the agar plates can we use for growing shigella?

A
  1. Desoxycholate-citrate agar
  2. Eosine-methylenblue ag
44
Q

II. Shigella
7B. What are the features of Desoxycholate-citrate agar?

A

It containing desoxycholic acid, sodium citrate, lead acetate, ferrous ammonium sulfate, lactose, and neutral red indicator
=> Shigellae: small, round-shaped, colourless colonies (lactose -, H2S-).

45
Q

II. Shigella
7C. What are the features of Eosine-methylenblue ag ar?

A

small, round-shaped, colourless colonies (lactose -)

46
Q

II. Shigella
8. How can we prevent shigella?

A

personal and food hygiene

AA Microbio Semifinal (99 decks)

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