MMI 301: Lecture 23: Borrelia and Treponema

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MMI 301: Lecture 23: Borrelia and Treponema
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  1. Borrelia Morphology
    • Gram -    -Stain poorly
    •    -Use Giemsa or Wright
    • Visible under bright-field
  2. Borrelia Motility
    Motile, endoflagellar structure in periplasm.
  3. Borrelia species
    • recurrentis: blood
    • burgdoferi: rarely visualized in clinical specimens.
  4. Growing Borrelia
    • -Grow Slowly
    • -Require complex media
    • -Microaerophilic conditions
    • -Optimal growth at 30 degrees
  5. How does Borrelia achieve motility?
    Periplasmic endoflagella move in helical waves
  6. Relapsing fever
    • Caused by Borrelia
    • Arthropod vector required
    •      -recurrentis carried by louse, epidemic (more dangerous, humans only reservoir)
    •      -hermsii carried by tick, endemic (less severe, animal reservoirs)
    • -Results in bacteremia, one week after bite, fever, headaches, last 3-7 days
    • -Can have several relapses
    •      -VMP (variable major protein) undergoes anti-genic change, body must make new antigens, causing bouts of the disease
  7. Lyme disease caused by:
    Borrelia burgdorferi
  8. Lyme disease
    • burgdorferi
    • Identified in 1981
    • Endemic to many parts of Wisconsin
    • One of most common arthropod diseases
  9. Epidemiology of Lyme disease
    • Transmitted to human by tick bite
    •      -Ixodes scapularis most common in wisco
    • Nymph and young responsible for most disease
    • Natural reservoirs: white-tail, field mouse, other mammals
  10. Tick life cycle
    • Born in summer to larvae
    • Dormant nymph through fall-spring
    • Become adults over summer, lay eggs in fall which become larvae next summer
    • -See most disease from them in spring/early summer
  11. Structure of Borrelia
    • Spirochete
    •     -Can be seen under bright-field, with Giesma/Wright
    •      -burgdoferi rarely seen in clinical specimens
  12. Genetics of Borrdelia
    • Linear chromosomes and plasmids
    • Major outer membrane proteins (Osp's) encoded by unusual linear plasmids
    • High rate of recombination leading to antigenic variation
    • No relapse- Osp variation has no effect on pathogenesis
  13. Membrane structure of Borrelia
    • Similar to other Gram -, but:
    • -No LPS in outer membrane
    • -Produce large # lipoproteins, many in OM-Osps (outer surface proteins)
    • -Have endo-periplasmic flagella (EF)
  14. Antigenic Variation of burgdorferi
    • Linear plasmid encodes variable lipoprotein VlsE
    • Plasmid contains one full vlsE gene and 16 partial copies
    • Partial copys can be put into full gene with recombinants
    • 16 flavors of LP allow avoidance of immune system
  15. Stages of Lyme disease
    • Stage 1: Erythema migrans (bulls eye rash) 3-30 days after infec, fever, headache, malaise, chills, muscle pain, stuff neck
    • Stage 2: Occurs in only 10-20%, secondary lesions, arthritis, Bell's palsy, neurological and cardiac symptoms.
    • Stage 3: Neuro/Cardio symp, arthritis resolves, 10% sever destructive arthritis, immune over-response the cause at this point.
  16. Diagnosis and Treatment of Lyme
    • Easily diagnosed, bull's eye rash/bite
    • Not seen in blood/tissues
    • Can use symptoms, history or serology in advanced cases
    •      -Anti-IgG borrelia antibodies more reliable than anti-IgM
  17. Failed Lyme vaccine
    • Developed 1998
    • Contained OspA (outer surface lipoprotein, immunodominant)
    • OspA only found in Borrelia infected ticks, prevented infection (blood goes into tick when they eat, fight bacteria)
    • Vaccine caused arthritis, no good
  18. Treponema do not use:
    Iron, Manganese instead (fact-check)
  19. Causitive agent of Syphilis:
    Treponema pallidum
  20. Spirochaetales:
    • Order
    • Includes T. pallidum, B. burgdorferi, L. interrogans
    • Placed based on helical cell shape
  21. Treponema p. Structure
    • Thin, relatively long helical structure
    • Cannot be seen on bright-field microscopy
    • Posses periplasmic flagellar structure used for motility
    • Technically gram -
  22. Disease/Pathogenesis
    Majorly unknown, cannot be grown on media, cannot be tested in animals, hard to research
  23. Stages of Syphilis
    • Stage 1: Lesion at site of infection
    •    -Painless, site of neutrophil/macrophage infiltration
    •    -Other aspects of disease from immune response
    • Stage 2: 2-12 weeks later, Organism spreads through body, general rash, lesions at local replication sites
    • Stage 3: Can occur years later, chronic inflammatory disease (granulomatous lesions in bone, brain, heart, skin), Neurosyphilis (chronic inflammation of CNS-->Paralysis, dementia, sensory loss)
  24. Congenital Syphilis
    • Transplacental transmission from mother-->fetus
    • Can result in deformation/stillborn
    • Child may be born into rapid secondary syphilis
  25. Syphilis transmission
    • Sexual Transmission
    • Contact with primary/secondary lesions can cause infection
    • Rarely transferred via infusion
    • Humans are reservoir
    • Bacteria sensitive to low temp/drying
    • Third most common STD
  26. Diagnosis of syphilis
    • Clinical presentation/dark-field microscopy on material from the lesions
    •      -helical organisms spotted      /Immunofluorescence with anti-treponemal antibodies also used 
    • Cannot be cultured in lab
    •      -No useful assays, can be killed with penicillin
  27. Serology diagnosis (Non-treponemal)
    • Non-treponemal:
    •    -Test for antibodies to cardiolipin
    •         -Antibodies produced in response to infection can aggregate cardiolipin
    •     -VDRL (Venereal Disease Research Laboratory)
    •           -Use patient sera to cause cardiolipin to flocculate
    •            -Very false positive
  28. Serology diagnosis (Treponemal)
    • -Fluorescent Treponemal antibody absorbtion (FAT-ABS)
    •       -Measure presence of specific anti-Treponema pallidum antibodies in the serum
    • -Immunoblotting
    •         -T. pallidum antigens separated by electrophoresis
    •         -Use patient serum and measure reactivity of the patients antibodies to the antigens.
  29. Tuskegee Experiment
    Researchers observed african-american that were infected with syphilis over 40 years, never treated them. Resulted in passage of laws for informed consent.

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