II-A. Systemic Bacteriology | 25. Rickettsia Flashcards

1
Q

I. Rickettsia genus
1. What are the main features of Rickettsia genus?

A
  1. Intracellular, Gram-negative coccobacilli
  2. Could be categorised based on clinical diseases
    - typhus group
    - spotted fever group
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2
Q

I. Rickettsia genus
2. Give the classification based on clinical diseases?

A
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3
Q

I. Rickettsia genus
3. What are the species of typhus group?

A
  • R. prowazekii ➡ (epidemic) typhus
  • R. typhi ➡ endemic typhus
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4
Q

I. Rickettsia genus
4. What are the species of spotted fever group?

A
  • R. rickettsii
  • R. conorii
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5
Q

II. Rickettsia prowazekii
1. What is the source of infection of Rickettsia prowazekii?

A

infected person

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6
Q

II. Rickettsia prowazekii
2. What is route of transmission of Rickettsia prowazekii?

A

by the bite of body louse (Pediculus humanus)

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7
Q

II. Rickettsia prowazekii
3. What are the 2 diseases caused by Rickettsia prowazekii?

A
  • epidemic (exanthematic) typhus
  • Brill-Zinsser disease: reactivation
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8
Q

II. Rickettsia prowazekii
4. What are the features of epidemic (exanthematic) typhus?

A
  • high fever, headache
  • rash (present on palms, soles, and face as well!)
  • confusion
  • mortality is high (c.a. 40%) in untreated cases!
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9
Q

II. Rickettsia prowazekii
5. What are the features of Brill-Zinsser disease?

A

Brill-Zinsser disease: reactivation
* usually milder than the primary disease
* infectious!

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10
Q

II. Rickettsia prowazekii
5. What are the features of Brill-Zinsser disease?

A

Brill-Zinsser disease: reactivation
* usually milder than the primary disease
* infectious!

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11
Q

III. Rickettsia typhi
1. What is the source of infection of Rickettsia typhi?

A

Rodents (rats – zoonotic!)

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12
Q

III. Rickettsia typhi
2. What is the route of transmission of Rickettsia typhi?

A

through the bite of rat flee (vector- borne!)

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13
Q

III. Rickettsia typhi
3. What is the disease caused by Rickettsia typhi?

A
  • high fever, headache
  • rashes (palms - soles - face are usually spared!)
  • disturbed state of consciousness
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14
Q

IV. Rickettsia rickettsii
1. Wha is the source of infection of Rickettsia rickettsii?

A

wild animals (zoonotic)

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15
Q

IV. Rickettsia rickettsii
2. What is the route of transmission of Rickettsia rickettsii?

A

by the bite of ticks (Dermacentor species)

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16
Q

IV. Rickettsia rickettsii
3. What is the pathomechanism of Rickettsia rickettsii?

A
  • infects capillary endothelial cells, spread from cell to cell
  • causes vasculitis (inflammation of vessels) in different organs
17
Q

IV. Rickettsia rickettsii
4. What is the disease caused by Rickettsia rickettsii?

A

Rocky-mountain spotted fever (RMSF)
- flu-like symptoms after a week of incubation
- rash usually starts on the wrists, ankles then spread to other parts of
the body (face is usually spared!)
- mortality is high (20%) if left untreated!

18
Q

V. Rickettsia conorii
1. What is the source of infection of Rickettsia conorii?

A

wild animals (zoonotic)

19
Q

V. Rickettsia conorii
2. What is the route of transmission of Rickettsia conorii?

A

by the bite of ticks

20
Q

V. Rickettsia conorii
3. What is the pathomechanism of Rickettsia conorii?

A
  • infects capillary endothelial cells, spread from cell to cell
  • causes vasculitis (inflammation of vessels) in different organs

(similar to RMSF)

20
Q

V. Rickettsia conorii
3. What is the pathomechanism of Rickettsia conorii?

A
21
Q

V. Rickettsia conorii
4. What is the disease caused by Rickettsia conorii?

A

mediterranean spotted ever
* similary to RMSF
* rash is usually present on the face as well

22
Q

VI. Diagnosis of Rickettsia and Orientia infections
1. What is the diagnosis of Rickettsia and Orientia infections?

A
23
Q

VI. Diagnosis of Rickettsia and Orientia infections
2. How do we do laboratory for Diagnosis of Rickettsia and Orientia infections

A

serology (it takes time for antibodies to be produced!)
1. immunofluorescence (IF): detection of anti-Rickettsia (anti-Orientia) antibodies from patient’s serum
2. Weil-Felix tube agglutination: etection of anti-Rickettsia antibodies from patient’s serum

24
Q

VI. Diagnosis of Rickettsia and Orientia infections
3. How do we perform immunofluorescence (IF) for Diagnosis of Rickettsia and Orientia infections?

A

Detection of anti-Rickettsia (anti-Orientia) antibodies from patient’s serum
- pre-made slides (containing Rickettsia / Orientia) antigens are incubated with patien’s serum, then secondary, fluorophore labeled antibodies are added, and the slide is examined under a fluorescent microscope

25
Q

VI. Diagnosis of Rickettsia and Orientia infections
4. How do we perform Weil-Felix tube agglutination for Diagnosis of Rickettsia and Orientia infections?

A

Detection of anti-Rickettsia antibodies from patient’s serum
- certain proteins of Rickettsia are quite similar to the proteins of Proteus vulgaris OX19
- we mix the patients serum with proteins of Proteus vulgaris OX19
- if agglutination is present, we could say that the patient MIGHT HAS antibodies against Rickettsia

26
Q

VII. What is the empirical therapy for Rickettsia and Orientia infections?

A

tetracyclins (doxycyclin)