Rickettsia

Question 1

Obligate intracellular. Replicate in cytoplasm of cells. Difficult to see in tissues - need giemsa stain

Answer 1

Rickettsia

Question 2

Causes rocky mountain spotted fever

Answer 2

Rickettsia rickettsii

Question 3

Has outer membrane protein A

Answer 3

rickettsia rickettsii

Question 4

Allows adherence to endothelial cells

Answer 4

outer membrane protein A

Question 5

Replication in cytoplasm and nucleus results in vasculitis

Answer 5

Rickettsia rickettsii

Question 6

Intracellular growth protects bacteria from clearance

Answer 6

rickettsia rickettsii

Question 7

Most common rickettsia causing human disease in USA

Answer 7

rickettsia rickettsii

Question 8

90% of infections from april-september

Answer 8

rickettsia rickettsii

Question 9

Vectors are ticks (lxodeae family)

Dermacentor adersoni and dermacentor variabilis

Answer 9

rickettsia rickettsii

Question 10

Dermacentor andersoni

Answer 10

Wood tick (rocky mountain states) of rickettsia rickettsii

Question 11

Dermacentor variabilis

Answer 11

Dog tick (SE US) of rickettsia rickettsii

Question 12

Occurs in Arkansas, Delaware, Missouri, North Carolina, Oklahoma, and Tennessee

Answer 12

rickettsia rickettsii

Question 13

Tick reservoir via transovarian transmission

Answer 13

Rickettsia rickettsii

Question 14

6-10 hours after tick bite dormant, avirulent bacteria are activated by warm blood meal. Translocation of bacteria from salivary glands to bloodstream

Answer 14

Rickettsia rickettsii

Question 15

Bacteria incubates 2-14 days. Centripetal rash on palms and soles of feet. Respiratory failure, encephalitis, renal failure, myocarditis
Fatal in 20% of untreated cases

Answer 15

RMSF

Question 16

Erythematous

macular > papular > petechial

Answer 16

RMSF

Question 17

Thrombocytopenia, coagulopathy, anemia, normal WBC count, hyponatremia, transaminitis

Answer 17

RMSF

Question 18

National notifiable disease

Answer 18

RMSF

Question 19

In acute phase RMSF organism best detected by _______ and ________

Answer 19

PCR

immunohistochemistry

Question 20

For RMSF paired _________ and _______ samples are essential for confirmation

Answer 20

acute

convalescent

Question 21

Fourfold increase in _______ for rickettsii between acute and convalescent serum comparisons

Answer 21

IgG

Question 22

Causes rickettsialpox

Answer 22

Rickettsia akari

Question 23

Transmitted by infected mites. Rodents (common house mouse) is reservoir. Humans accidental hosts when bitten by infected mites

Answer 23

Rickettsia akari

Question 24

Rickettsialpox has ____________ presentation

Answer 24

biphasic

Question 25

Gram - bacilli. Minimal peptidoglycan layer. LPS weak endotoxic activity. No beta-lactam treatment

Answer 25

Rickettsia

Question 26

First phase - 1 wk after bite. Papule > ulcer > eschar at bite site. Incubation 7-24 days, then systemic spread. Second phase: High fever, severe headache, photophobia, papulo-vesicular rash, pox-like progression (vesicles crust over) Milder course than RMSF

Answer 26

Rickettsialpox

Question 27

Must be differentiated from anthrax

Answer 27

rickettsialpox

Question 28

Anthrax patients only have ______

Answer 28

eschar

Question 29

Can be either epidemic or sporadic. Epidemic - louse born typhus USA sporadic - fleas from flying squirrels

Answer 29

Rickettsia prowazekii

Question 30

Humans main reservoir. Transmitted by pediculus humanus (body louse) Rare in USA - seen in disasters, war, famine

Answer 30

Epidemic (louse-borne) typhus

Question 31

During blood meal, louse defecates highly infective feces at feeding site. Bacteria present in louse feces introduced into bite site. Lice feces may remain infectious for as long as ____ days > can have human to human transmission via clothes

Answer 31

Rickettsia prowazekii 100

Question 32

Can have 2 syndromes - acute, severe vasculitis form or recrudescent form

Answer 32

Rickettsia prowazekii

Question 33

7-14 days after contact with infected lice. Fever, CNS sxs. | Centrifugal maculopapular rash

Answer 33

Acute, potentially severe vasculitis of Rickettsia prowazekii

Question 34

10-50 yrs after primary infection. | Milder form. Rash, flu-like sxs. Elderly pts (WWII refugees)

Answer 34

Recrudescent form (Brill-Zinsser disease) of Rickettsia prowazekii

Question 35

Diagnose by serology MIF test

Answer 35

Rickettsia prowazekii

Question 36

American Boutonneuse fever/Tidewater spotted fever

Answer 36

Rickettsia parkeri

Question 37

Recently described (index case 2002). Mainly southern USA (in VA).

Answer 37

Rickettsia parkeri

Question 38

Vector is amblyomma maculatum (gulf coast tick).

Answer 38

Rickettsia parkeri

Question 39

Several eschars and rash. Low mortality. Serology, PCR, culture from skin biopsy

Answer 39

Rickettsia parkeri

Question 40

Perivascular mononuclear inflammatory cell infiltrates and edema of adjacent superficial dermis and intact epidermis

Answer 40

Rickettsia parkeri

Question 41

Endemic (murine) typhus. | Worldwide. More in warm, humid areas

Answer 41

Rickettsia typhi

Question 42

Reservoir is rodents. | Main vector is xenopsylla cheopis (rat flea). Also cat flea in USA

Answer 42

Rickettsia typhi

Question 43

Inoculated by infective flea feces in bite wounds

Answer 43

Rickettsia typhi

Question 44

Mild and non-specific symptoms. Variable presentation of rash. Serology by IFA

Answer 44

Rickettsia typhi

Question 45

With ________ diseases, early reliable diagnosis is not possible. Clinical presentation and epidemiological setting is key

Answer 45

rickettsial