Bacteria IV: Rickettsial diseases

Question 1

intracellular vector-borne diseases

Answer 1

• typhus (lice)
• rocky mountain spotted fever (ticks)
• Erlichiosis-> ticks

Question 2

Extracellular vector-borne diseases

Answer 2

lyme disease (ticks)
relapsing fever (lice or ticks)
plague (fleas)

Question 3

what does rickettsia infect?

Answer 3

intracellular infection of endothelial cells with perivascular lymphocytic infiltrate (perivascular cuffing)

Question 4

rickettsia characteristics

Answer 4

small, G-, obligate intercellular bacteria

• ticks
• dark, swollen, crusted lesion

Question 5

how do you diagnose rickettsial disease?

Answer 5

immunostaining or serology or exposure to vector

Question 6

where does rickettsia multiple?

Answer 6

small vessel endothelial

Question 7

triad related to rickettsia diseases?

Answer 7

rash, fever, CNS manifestations (headache, seizures)

-small vessel vasculitis with microthrombi, ischemia and hemorrhage

Question 8

what does the typhus group do to endothelial cells?

Answer 8

lysis

Question 9

what does the spotted fever group do to endothelial cells?

Answer 9

spread cell to cell

Question 10

does rickettsia have toxins?

Answer 10

No endotoxins, no exotoxins

• LPS non-toxic
• small vessel damage: thrombosis and hemorrhage

Question 11

what are the first cells to come in for rickettsial diseases?

Answer 11

1st-> Natural killer cells-> produce gamma-interferon

2nd-> cytotoxic T cells mediated immune responses responsible for much of the tissue damage seen

Question 12

clinical features from rickettsia

Answer 12

fever, rash, CNS symptoms

-severe cases: hypovolemic shock, DIC, pulmonary edema

Question 13

treatment for rickettsia

Answer 13

doxycycline

Question 14

typhus group of rickettsia

Answer 14

R. bellii

R. canadensis

Question 15

other group of rickettsia

Answer 15

R. prowazekii

R. typhi

Question 16

R. prowazekii: Epidemic typhus

Answer 16

head lice

• centrifugal rash, CNS involvement (apathy, dullness, stupor, coma)
• high fever, chills, cough, rash, severe muscle pain, sensitivity to light, delirium

Question 17

murine typhus

Answer 17

related syndrome to epidemic typhus

-high density population and poor hygiene

Question 18

clinical findings R. prowazekii: Epidemic typhus

Answer 18

mild rash, small hemorrhages

severe: gangrene of tips of fingers, nose, earlobes, scrotum, penis, vulva

Question 19

R. prowazekii: Epidemic typhus morphology

Answer 19

cuff of mononuclear inflammatory cells around vessels
ecchymotic hemorrhages of affected organs
microthrombi
no necrosis of vessels

Question 20

rocky mountain spotted fever group

Answer 20

R. rickettsia, tick bite
incubation time 7 days
-fever (high 2-3 weeks), N&V, headache, muscle pain

Question 21

when does the rash appear for rocky mountain spotted fever

Answer 21

day 6 of fever
extends over all body, INCLUDING palms, soles
-begins in periphery (palms wrists, soles)-> then to trunk, face and neck

Question 22

rocky mountain spotted fever morphology

Answer 22

perivascular mononuclear infiltrate
necrosis, fibrin extravasation and thrombosis of small blood vessels and arterioles
-severe cases-> foci of necrotic skin, fingers, toes, elbows, ears, scrotum

Question 23

what is the major death from rocky mountain spotted fever

Answer 23

noncardiogenic pulmonary edema

Question 24

Scrub typhus

Answer 24

Orienta (rickettsia tsutsugamushi)

• rash transitory or absent
• transmitted by mites

Question 25

Ehrilichiosis

Answer 25

``` similar to RSMF -rash rare -(infects)Neutrophils or monocytes -cytoplasmic inclusions-> shaped like mullberries ticks ```

Question 26

Lyme disease (Borrelia burgdorferi)

Answer 26

tick of white tailed deer | -shift antigenic markers to avoid antibody production

Question 27

what is the primary stage of Lyme disease?

Answer 27

local infectio | -skin rash shows vasodilation with dense perivascular inflammatory infiltrates of mononuclear leukocytes

Question 28

what is the secondary stage of Lyme disease?

Answer 28

spread, Late (months) - bacteremia disseminates the spirochetes to many with focal necrosis, hemorrhages - joint disease - muscle pain, cardiac arrhythmias, meningitis, cranial nerve involvement

Question 29

what is the tertiary stage of Lyme disease?

Answer 29

multisystem chronic inflammation disease - local lesion progresses to bacteremia and chronic inflammatory lesions in distant organ - manifestations include chronic arthritis, polyneuropathy and encephalitis, skeletal muscle involvement

Question 30

what toll like receptor does LPS bind to in Lyme disease?

Answer 30

TLR2 of macrophages

Question 31

why does the bull's eye (target) rash appear in lyme disease?

Answer 31

spreading erythematous margins and a blanching center - erythema chronicum migrans - fever and constitutional symptoms may occur at this point

Question 32

lyme disease pathogenesis

Answer 32

focal necrosis, hemorrhages and DIC -rash shows vasodilation with dense perivascular inflammatory infiltrates of mononuclear leukocytes (lymphoplasmacytic cell infiltrate)

Question 33

how does lyme disease resemble rheumatoid arthritis

Answer 33

synovial hyperplasia lymphocytes, plasma cells proliferative arteritis

Question 34

relapsing fever (Borrelia recurrentis)

Answer 34

lice 1-2 week latent period, shaking, chills, fever, headache, fatigue -successive attacks results from ability of organism to expressive new surface antigen

Question 35

Plague, Yersinia Pestis

Answer 35

G- bacillus | -Sylvatic cycle (organism cycle in rodents)

Question 36

Plague, Yersinia Pestis pathogenesis

Answer 36

rapid proliferation in lymphoid tissues - injection of YOP's, yersinia outer proteins - inactivation molecules that regulate actin polymerization, inhibits secretion of inflammatory cytokines - necrosis of tissue and blood vessels - swelling of lymphoid tissue, striking leukocytosis, septicemia/DIC

Question 37

what constitutes minor plague symptoms?

Answer 37

lymphadenopathy and constitutional symptoms

Question 38

what constitutes bubonic plague symptoms?

Answer 38

prominent lymphadenopathy, most common

Question 39

what constitutes pneumonic plague symptoms?

Answer 39

hemorrhagic, necrotizing pneumonia primary or secondary to bubonic infections -septicemia-> rapidly fatal