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Micro Post Quiz 3 JXC > 4. Spirochetes > Flashcards

4. Spirochetes Flashcards

1
Q

What are the three major genera of spirochetes?

A
  1. treponema
  2. borrelia
  3. leptospira
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2
Q

What causes syphilis? Why is it difficulty to see under light microscopy? How can you improve visibility? What are its physical and biochemical characteristics?

A
  • -Treponema pallidum
  • -hard to see b/c they are long, but wicked skinny; use darkfield, immunofluoro, silver salts or EM
  • -cannot be cultured!
  • -would be Gm-, motile, helicoid and flexible w/ axial filament = internal flagella
  • -easily killed by heat, soap & water, or drying but very resistant to freezing (revived after -80°C!)
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3
Q

What are the stages of syphilis and how do you dx each one?

A

1° after 1-4 wks incubation

  • infectious
  • -DERM: spontaneously-healing, genital chancres
  • -SYST: focal lymphadenopathy

2° after 2-10 wks post 1° onset

  • infectious
  • -DERM: generalized papulosquamous rash, condyloma lata
  • -SYST: h/a, f/c, leukocytosis, wt. loss, sore throat
  • -RENAL: dysfunction

3° after 2-20 years

  • not infectious
  • -SYST: gummas, hypersensitivity
  • -CNS: paresis, meningitis, tabes dorsalis
  • -COR: aortic valves, aortic aneurysm
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4
Q

How is syphilis tx?

A

“Syphilis is exquisitely sensitive to antibiotics.”

  • -Pen G IM x 1 dose
  • -if allergy: long course of doxy
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5
Q

What are other treponemal disease?

A

Yaws, Bejel and Pinta

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6
Q

What causes yaws? Properties? Tx?

A

T. pertenue in tropical areas

  • -open skin sore transmission
  • -children
  • -no trans-placental trans
  • -Primary lesions = mother yaw = raspberry
  • -sensitive to Pen G
  • -will cause false positive T. pallidum tests
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7
Q

What causes bejel? Properties? Tx?

A

T. pallidum ssp. “endemicum”

  • -Syrian peds
  • -Similar to yaws
  • -No venereal trans
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8
Q

What causes pinta? Properties? Tx?

A

T. carateum in Central and S Amer

–flat, non-ulcerating skin lesions of hands, feed and scap that heal spontaneously –> depigmented area left behind

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9
Q

What are other, non-treponemal spirochete pathogens?

A
  • -Borrelia spp.

- -Leptospira spp.

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10
Q

What causes lyme disease?

A

Borrelia burgdorferi which is visible in light microscopy; can only be cultured in chick embryo thus far

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11
Q

What is the reservoir and vector of lyme dz?

A

white footed mouse is reservoir

–Ixodes spp. ticks = vector

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12
Q

What is the pathogenesis of lyme dz?

A

Three stages:

  1. 3-14 days after bite: bulls-eye expanding erythema chronicum nigrans w/ fever, h/a, stiff neck and malaise
  2. various neuro and cardio sx; bilat facial nerve palsy
  3. arthritis; occur weeks to months after bite and may last years
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13
Q

Dx Lyme dz?

A
  • -sx (e.g. bulls-eye rash)

- -ELISA for circulating Abs

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14
Q

Tx Lyme dz?

A

tetracycline; ampicillin for young kids

–PenG or ceftriaxone work, too

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15
Q

Leptospira pathogenesis and sx?

A

transmitted by rats, dogs and other animals; occ hazard for sewage workers, slaughter house, rat-infested areas

  • -infected urine
  • -ingestion or mucus membrane entry–> circulation–>end organs
  • -biphasic w/ illness followed by remission followed by immunopathology
  • -causes Weil’s dz (infectious jaundice), nephritis, meningitis
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16
Q

Leptospira dx?

A

culture or serological ID

17
Q

Leptospira tx?

A

Penicillin; erythromycin and tetracycline

18
Q

Is there a vaccine for Lyme? For Leptospira?

A

There was one for Lyme against outer surface protein A (OspA) that was given to those at high risk (e.g. foresters), but it is no longer available.
–There is no vaccine for Leptospira

19
Q

How is syphilis transmitted?

A

3 ways:

  • -genital contact
  • -vertical transmission via placenta
  • -very rare: blood transfusion (rare b/c cannot live in blood alone for very long time)
20
Q

How do you dx syphilis?

A
  1. Microscopy with darkfield
  2. Non-Specific Serology
    - -use cardiolipin to react with serum samples of pts w/ suspected syphilis case (e.g. VDRL=viral dz research lab; RPR=rapid plasma reagin)
  3. Specific Serology
    - -more expensive, more specific (i.e. fewer false positives)
    - -immunofluorescence (FTA-ABS) or micro-hemagglutination with Abs in the pt’s serum
    - -ELISA–USED AT DHMC
    - -TPI T. palldium immobilization; important if false poz suspected
    - -will remain positive even after tx (vs. non-specific tests)
21
Q

What causes relapsing fever?

A 
Borrelia recurrentis (epidemic, not in U.S., louse transmission)
An Borrelia hernsii (endemic in W U.S. ticks-->rodents-->ticks-->humans)
22
Q

What is the clinical course of relapsing fever?

A

4-5 days fever, 7-10 afeb

–wash, rinse repeat 3-10 times

23
Q

How do you dx relapsing fever?

A
  • -blood smear

- -bioassay (inject into mouse)

24
Q

How do you tx relapsing fever?

A

-tetracycline derivatives

Micro Post Quiz 3 JXC (6 decks)

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