Ricketsia Flashcards Preview

FM3_ EB > Ricketsia > Flashcards

Flashcards in Ricketsia Deck (38):
1

Rickettsia are obligate ______ pathogens and will not show up on Gram stain

intracellular

2

List the causative agent of Rocky Mountain Spotted Fever

Rickettsia rickettsii

3

List the causative agent of Mediterranean spotted fever

Rickettsia conorii

4

List the causative agent of African tick bite fever

Rickettsia africae

5

List the causative agent of murine (endemic) typhus and its mode of transmission

Rickettsia mooseri (typhi), fleaborne

6

List the causative agent of Q fever

Coxiella burnetti

7

List the causative agent of epidemic typhus and its mode of transmission

Rickettsia prowazekii, louseborne

8

List the two rickettsial diseases that can be transmitted by inhalation

Q fever (coxiella burnetii)
epidemic typhus (Rickettsia prowazekii)

9

Describe the pathogenesis of Rickettsial diseases

- vasculitis caused by invasion of organism in the endothelium and smooth muscle of vessels
- thrombosis, occlusion, and necrosis of vessel walls
- thrombocytopenia (consumptive) and hemorrhage NOT true DIC
- capillary leakage resulting in edema, hypovolemia, hypotension, ARDS
- ADH produced in response to hypovolemia leading to hyponatremia

10

_____ is released in response to the hypovolemia seen in rickettsial infection, leading to hyponatremia

ADH

11

What is the classic triad seen in RMSF?

fever, headache, rash
- with appropriate travel/ exposure history

12

What geographic region is associated with RMSF?

Southeast US, especially North Carolina

13

The rash in RMSF is _____ - it starts in the extremities and moves toward the trunk

centripedal

14

Involvement of the ____ and ____ is considered a classic feature of the rash with RMSF

palms and soles

15

List other symptoms that are associated with RMSF

- myalgia
- abdominal pain
- nausea/ vomiting
- periorbital edema
- conjunctival suffusion

16

Will there be an eschar at the site of inoculation in RMSF?

NO eschar at the site of the tick bite

17

Outline the timeline of Rickettsia ricketsii infection

- 2-14 day incubation then fever, headache, myalgia
- petechial rash by day 3-5 of illness

18

How is the diagnosis of RMSF made?

Clinical suspicion (start antibiotics)
Indirect immunofluorescent antibody (IFA) confirmation takes weeks

19

How is Rickettsia prowazekii transmitted?

Causative agent of epidemic typhus
Spread person to person by the human body louse
Outbreaks in times of war, natural disaster, great poverty- inability to bathe and wash clothes in hot water

20

Outline the timeline of Rickettsia prowazekii infeciton

Incubation of 8-16 days then severe headache, fever, myalgias, central rash

21

What are the main symptoms of epidemic typhus

sever headache, fever, myalgia, central rash, mental status changes

22

What animal is associated with outbreaks of epidemic typhus in the US?

Flying squirrels- asymptomatic reservoir
Found mainly in Southwest US

23

What is Brill-Zissner disease?

Mild, recrudescent form of epidemic typhus seen months-years after initial infection

24

How is Q fever transmitted?

Organism is aerosolozied from feces, urine, milk, infected placenta of sheep, cattle, goats
NO arthropod vector

25

What are the symptoms of Q fever?

range from self limited febrile illness to Q fever pneumonia (with severe headache), Q fever hepatitis, Q fever endocarditis

26

____________ is a characteristic histologic finding of Q fever

Donut shaped non-caseating granuloma

27

How is the diagnosis of Q fever made?

Specific serology

28

Mediterranean spotted fever is found in France, Spain, Africa, Asia, and is transmitted by ________

dog ticks

29

How does Mediterranean spotted fever present?

Fever, constitutional symptoms, generalized flat red rash, inoculation eschar at the site of the tick bite
Severe cases have neurologic involvement and peripheral gangrene

30

________ is the most common rickettsial infection seen in travel medicine

African tick bite fever

31

African tick bite fever is most strongly associated with what country?

South Africa

32

How is Rickettsia africae transmitted?

bite of cow tick

33

How does African tick bite fever present?

headache, myalgia, inoculation eschars (can have multiple), regional lymphadenopathy
can see mouth blisters and disseminated vesicular rash

34

List serologic tests that are used to diagnose rickettsial infections

- indirect immunofluorescent antibody
- indirect hemagglutination antibody
- complement fixation

either four fold increase or a single high titer is confirmatory

PCR is emerging

35

The _______ reaction was formerly used to diagnose rickettsia, but it is both insensitive and non-specific

Weil-Felix reaction

36

Why is early treatment so important in severe RMSF, Q fever, and typhus infections?

Prevention of severe endothelial damage helps avoid complications of multi-system organ failure

37

List drugs used to treat rickettsia infections

Doxycycline is DOC, can be given IV
Tetracycline
Chloramphenicol (not available in US, risk of aplastic anemia)

38

List some strategies to prevent rickettsia infection

Minimize exposure to arthropod vectors
Inspection for ticks, removal
Louse infestations must be treated