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MY Bacteriology exam 2 > Rhodococcus > Flashcards

Rhodococcus Flashcards

1
Q

What color is rhodococcus?

A

Red colored- after 24 hours produce pink colonies in the agar

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2
Q

Who are the main host for this bacteria?

A

Horses- Especially foals 1-6 months old

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3
Q

mainly associated with what types of lesions?

A

granulose and pyogranulous

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4
Q

What kind of cell wall does this bacteria have?

A

very Lipid rich!

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5
Q

Is rhodococcus acid fast positive or negative?

A

Acid fast positive- rich in mycolic acid

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6
Q

Rhodococcus is a facultative _____ organism

A

intracellular

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7
Q

What cells do Rhodococcus live in?

A

Macrophages- develop granulomas

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8
Q

What kind of immune response do we want for Rhodococcus?

A

cell mediated immune response- Th1

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9
Q

Is rhodococcus aerobic or anaerobic?

A

Aerobic

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10
Q

Rhodococcus is: catalase _____ oxidase ______ CAMP ______

A

positive, negative, positive

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11
Q

True or False: Rhodococcus is spore forming and non motile

A

FALSE- non- spore forming and non motile

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12
Q

Rhodococcus are gram positive ____

A

bacilli- (very small and can look like cocci) also can be pleomorphic with rods and cocci

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13
Q

Does Rhodococcus have a capsule?

A

Yes, they are encapsulated

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14
Q

Picture of Gram stain for Rhodococcus

A

Pleomorphic gram stain

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15
Q

Would Rhodococcus be positive or negative on the Ziehl-Neelsen stain?

A

positive, because this is the acid fast stain

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16
Q

What is the only pathogenic species of Rhodococcus?

A

Rhodococcus Equi

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17
Q

What does rhodococcus equi cause in foals?

A

pneumonia

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18
Q

The antibiotic that you use needs to ____ the cell

A

penetrate

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19
Q

What are the virulence factors of Rhodococcus?

A

Capsule, cell wall, and Vaps

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20
Q

Why does Rhodococcus want C3b to bind to them?

A

They want to be opsonized so that the macrophages will take them in. Once inside the macrophage, they will replicate

21
Q

Does Rhodococcus want to be uptaken by the FC receptor?

A

no- they will get killed via this pathway

22
Q

Is the capsule anti-phagocytic?

A

not in Rhodococcus! They want to be taken up by the macrophages

23
Q

What are Vaps?

A

virulence associated proteins

24
Q

Rhodococcus equi that has lost its plasmid and do not produce Vaps are ____ in virulence

A

lower

25
Q

______ have genes that will code for the virulence associated proteins

A

Pathogenicity islands

26
Q

What is the role of pathogenicity islands?

A
  1. intracellular survival 2. down regulation of IFN gamma 3. Temperature regulation
27
Q

Why does Rhodococcus down regulate IFN gamma?

A

IFN gamma is one of the key cytokines necessary for Th1 activation of the cell mediated immunity

28
Q

Does Rhodococcus survive in the environment for long periods of time?

A

YES- it can persist in dry environments

29
Q

What environment does Rhodococcus persist in?

A

Soil and animal manure

30
Q

Does Rhodococcus have high variability?

A

yes!- many different antigens present in the capsules

31
Q

How is Rhodococcus transmitted?

A

inhalation, ingestion or congenitally

32
Q

Pathogenesis of Rhodococcus

A
  1. Opsonization by C3b and will be taken in by macrophages
  2. Induces Vaps and survives inside the phagolysosome
  3. Down regulates IFN gamma
  4. Causes pyogranulomatose to granulomatose lesions
33
Q

What will the prognosis of foals depend on?

A

The passive immunity and the amount of maternal anitbodies in the foal. Also, if the bacteria have the plasmid that encode for the pathogenicity island then the Vaps will be more virulent

34
Q

What are the elements of the granulomatous inflammation?

A

macrophages, giant cells and neutrophils

35
Q

What is the main manifestation in Foals?

A

Pneumonia- produces large abscesses in the lungs and lymph nodes

36
Q

What happens if Rhodococcus is swallowed and gets into the GI tract?

A

Ulcerative intestinal lesions

37
Q

What is the fatality rate in foals?

A

50%

38
Q

Rhodococcus equi causes what in the lungs?

A

Pyogranulomatous Bronchopneumonia

39
Q

What does Rhodococcus equi cause in the GI tract?

A

enteritis

40
Q

Does Rhodococcus affect Humans?

A

It can cause pneumonia in immunocompromised individuals. Mortality can reach 50%

41
Q

What does Rhodococcus cause in swine?

A

Nasty lesions of the lymph node

42
Q

When is the seasonal peak for Rhodococcus?

A

Summer- heat and dust

43
Q

What kind of immunity do you want?

A

Both cell mediated and Humoral immunity, however cell mediated is much more important. Antibodies for the foals are extremely important

44
Q

Is there a vaccine for Rhodococcus?

A

No

45
Q

What will you see in stains of infected tissue?

A

Intracellular and extracellular clusters of Gram positive cocci or rods. Completely packed macrophages

46
Q

What will the media show with Rhodococcus growth?

A

non hemolytic mucoid colonies

47
Q

This bacteria has a positive CAMP test with _____

A

Staph aureus or C. pseudotuberculosis- when cultured with these bacteria it produces complete hemolysis

48
Q

What is the treatment?

A

Sick foal should be isolated and treated with antimicrobials (drug needs to penetrate the macrophages).

PREVENTION is key

  • good colostrum is very important
  • dust control
49
Q

Do foals have a good or bad prognosis?

A

Bad

MY Bacteriology exam 2 (18 decks)

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