Bacterial Infections of the Vascular System: Rickettsia, Burnetii, Ehrlichia, and Anaplasma

Question 1

What are the vectors of Rickettsia, Ehrlicia, and Anaplasma species?

Answer 1

Arthropod vectors

Question 2

To what drug are Rickettsia, Ehrlichia, and Anaplasma sensitive?

Answer 2

Tetracycline (doxycycline)

Question 3

What bug is Q fever caused by?

Answer 3

Coxiella burnetii

Question 4

How is Q fever transferred?

Answer 4

By aerosols

Question 5

In what type of cell does Coxiella burnetii proliferate?

Answer 5

Alveolar monocyte/macrophages

Question 6

What is the second choice Tx for pregnant and allergic patients for Rickettsia? Q Fever? Erlichia? Anaplasma?

Answer 6

Chloramphenicol (Rickettsia); Fluoroquinolones (Q Fever, Enrlichia, Anaplasma)

Question 7

What is the proper technique to remove a tick?

Answer 7

Tweezers while wearing gloves, promptly

Question 8

What bug is epidemic typhus caused by?

Answer 8

Rickettsia prowazekii

Question 9

For which bugs are humans the proper host and reservoir?

Answer 9

Rickettsia prowazekii (Epidemic typhus); Others are all transmitted to humans by promiscuous vectors

Question 10

What diseases do Ehrlichia and Anaplasma cause? Typical presentation?

Answer 10

Erlichiosis and Anaplasmosis; Similar to spotted fever without the spots

Question 11

Where do Rickettsia, Erlichia, Anaplasma, and Coxiella replicate?

Answer 11

Within infected cells; Ehrlichia and Anaplasma form morulae within phagocytic vacuoles

Question 12

What is the major difficulty with identifying these bugs microscopically?

Answer 12

They are difficult to stain chemically and require IHC assay to visualize

Question 13

What is the policy for treating small children and pregnant women for these bugs?

Answer 13

Children can be treated with tetracyclines but pregnant women CANNOT

Question 14

What disease does Rickettsia rickettsia cause?

Answer 14

Rocky Mountain Spotted Fever

Question 15

What disease does Rickettsia conorii cause?

Answer 15

Mediterranean Spotted Fever

Question 16

What disease is caused by Rickettsia typhi?

Answer 16

Murine Typhus

Question 17

What bug causes Scrub typhus?

Answer 17

O. tsutsugamushi

Question 18

What are the 4 virulence factors of Rickettsia rickettsia?

Answer 18

1. Omp A & B: Adhesion
2. Type 4 Secretion System: Entry
3. Phospholipase A2: Escape from endosome
4. ActA: Actin-based cell-cell spread

Question 19

A patient is bitten with a tick and the lesion below is observed. The patient shows mild symptoms. What is the name of this lesion? What is the Dx? What is the bug?

Answer 19

• Eschar
• Mediterranean Spotted Fever
• Rickettsia conorii

Question 20

What is Brill-Zinnser disease?

Answer 20

Recrudescent (recurring) typhus caused by Rickettsia prowazekii seen in malnourished patients or those treated with improper/incomplete antibiotic therapy

Question 21

What is the vector of Rickettsia prowazekii?

Answer 21

Lice

Question 22

What is the vector for murine typhus?

Answer 22

Flea

Question 23

A patient presents with pneumonia and hepatitis. The patient is a farmer and is commonly around sheep and goats. His chest xray is shown below. What is the likely Dx?

Answer 23

Q Fever caused by Coxiella burnetii

Question 24

For what bugs are vaccines available?

Answer 24

Rickettsia prowazekii and Coxiella burnetii (Only of the military variety)

Question 25

A patient presents during the summer with mild fever, chills, headache and cough. The patient has a Hx of a tick bite. What two bugs are on your DDx? What would you suspect if this patient presented in a cold weather season, no Hx of a tick bite and had a SHx of living in crowded conditions?

Answer 25

Murine typhus (R. typhi) and Scrub typhus (O. tsutsugamushi); Epidemic typhus (R. prowazekii)

Question 26

A patient presents with fever, headache, myalgias, shaking chills, and a Hx of hiking. The patient was asymptomatic previously. Shown below is the blood smear. What two bugs are in your DDx? What is your first line Tx? Second line?

Answer 26

Anaplasma and Ehrlichia; Tetracyclines (Doxycycline); Fluoroquinolones