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MY Bacteriology exam 2 > Rhodococcus > Flashcards

Flashcards in Rhodococcus Deck (49):
1

What color is rhodococcus?

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

2

Who are the main host for this bacteria?

Horses- Especially foals 1-6 months old

3

mainly associated with what types of lesions?

granulose and pyogranulous

4

What kind of cell wall does this bacteria have?

very Lipid rich!

5

Is rhodococcus acid fast positive or negative?

Acid fast positive- rich in mycolic acid

6

Rhodococcus is a facultative _____ organism

intracellular

7

What cells do Rhodococcus live in?

Macrophages- develop granulomas

8

What kind of immune response do we want for Rhodococcus?

cell mediated immune response- Th1

9

Is rhodococcus aerobic or anaerobic?

Aerobic

10

Rhodococcus is: catalase _____ oxidase ______ CAMP ______

positive, negative, positive

11

True or False: Rhodococcus is spore forming and non motile

FALSE- non- spore forming and non motile

12

Rhodococcus are gram positive ____

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

13

Does Rhodococcus have a capsule?

Yes, they are encapsulated

14

Picture of Gram stain for Rhodococcus

Pleomorphic gram stain 

A image thumb
15

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

positive, because this is the acid fast stain

16

What is the only pathogenic species of Rhodococcus?

Rhodococcus Equi

17

What does rhodococcus equi cause in foals?

pneumonia

18

The antibiotic that you use needs to ____ the cell

penetrate

19

What are the virulence factors of Rhodococcus?

Capsule, cell wall, and Vaps

20

Why does Rhodococcus want C3b to bind to them?

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

21

Does Rhodococcus want to be uptaken by the FC receptor?

no- they will get killed via this pathway

22

Is the capsule anti-phagocytic?

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

23

What are Vaps?

virulence associated proteins

24

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

lower

25

______ have genes that will code for the virulence associated proteins

Pathogenicity islands

26

What is the role of pathogenicity islands?

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

27

Why does Rhodococcus down regulate IFN gamma?

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

28

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

YES- it can persist in dry environments

29

What environment does Rhodococcus persist in?

Soil and animal manure

30

Does Rhodococcus have high variability?

yes!- many different antigens present in the capsules

31

How is Rhodococcus transmitted?

inhalation, ingestion or congenitally

32

Pathogenesis of Rhodococcus

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

What will the prognosis of foals depend on?

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

What are the elements of the granulomatous inflammation?

macrophages, giant cells and neutrophils 

35

What is the main manifestation in Foals?

Pneumonia- produces large abscesses in the lungs and lymph nodes 

36

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

Ulcerative intestinal lesions 

37

What is the fatality rate in foals?

50%

38

Rhodococcus equi causes what in the lungs? 

Pyogranulomatous Bronchopneumonia 

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39

What does Rhodococcus equi cause in the GI tract?

enteritis 

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40

Does Rhodococcus affect Humans?

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

41

What does Rhodococcus cause in swine?

Nasty lesions of the lymph node 

42

When is the seasonal peak for Rhodococcus?

Summer- heat and dust 

43

What kind of immunity do you want?

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

44

Is there a vaccine for Rhodococcus?

No

45

What will you see in stains of infected tissue?

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

46

What will the media show with Rhodococcus growth?

non hemolytic mucoid colonies 

47

This bacteria has a positive CAMP test with _____

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

48

What is the treatment?

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

Do foals have a good or bad prognosis?

Bad