MedMicroTest3Spirochetes

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victimsofadown
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MedMicroTest3Spirochetes
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2013-11-07 07:18:09
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MedMicroTest3Spirochetes
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  1. General information about Spirochetes (shape, motility, gram, aeration, growth factors, important human pathogens w/ disease)
    • long and slender corkscrew shape
    • undulating motility
    • varies depending on species
    • some cannot be cultured
    • Treponema pallidium: syphilis
    • Borrelia burgdorferi: Lyme disease
    • Borrelia recurrentis: relapsing fever
    • Leptospira interrogans: leptospirosis
  2. Describe the structural features of Spirochetes
    • cylinder bounded by plasma membrane and gram negative cell wall surrounded by outer sheath
    • Endoflagella (axial filaments) propel the cell in a corkscrew manner and allow movement through viscous solutions (tissue)
  3. General information about T. pallidum (disease, aeration, culture requirements, strength of organism, other important info)
    • syphilis
    • anaerobic
    • cannot be cultured in lab
    • very fragile (heat, drying, disinfectants, etc)
    • divides slowly
    • True intracellular parasite¬† (lacks TCA, ETC, catalase, and oxidase)
    • Cannot be observed by light microscopy (too thin)
  4. Transmission of T. pallidum
    • Sexual contact: oral, vaginal, anal
    • Transplacental transmission: doesn't occur in birth canal (bacteria dies too quickly)
    • Enters body through break in skin/penetrates mucous membrane
  5. Describe the diseases caused by T. pallidum w/ description
    • Primary syphilis: chancre (genital or oral)
    • Heals after 6 weeks, but organism spreads via lymph and blood
    • Secondary syphilis: after asymptomatic period
    • Maculopapular rash that is EXTREMELY infectious
    • A latent period occurs after rash heals
    • Tertiary syphilis: degeneration of nervous system (resembling severe mental illness)
    • lesions on liver, skin, and bones
    • Not transmissible at this stage
    • Congenital syphilis: transmitted through placenta to fetus
    • Most often causes death and spontaneous abortion, stillbirth
    • If infants survive they develop a condition similar to secondary syphilis
  6. lab ID of T. pallidum
    • Serological ID using antibodies against T. pallidum
    • enzyme immunoassays
    • problem-assays remain positive for years after treatment
  7. Treatment of T. pallidum
    • One treatment with penicillin (no resistance)
    • Treatment for mother prevents congenital syphilis
    • Patients are often associated with HIV and should be tested for additional diseases
  8. Prevention of T. pallidum
    • No vaccine
    • Depends on safe sexual practices
    • 8000+ new cases each year despite effective cure
  9. What is unique about B. burgdorferi?
    • Linear, no circular, chromosome!
    • 3rd genome ever sequenced
  10. Describe the disease caused by B. burgdorferi in detail
    • Lyme disease (endemic relapsing fever)
    • The most common arthropod-transmitted disease in the US
    • Transmitted by bite of tick
    • Rodents and deer act as primary reservoires
    • First stage: red circular lesion with clear center at site of bite
    • 3-6 days of fever, 7-10 days of wellness, repeated 3-10 times
    • Second stage: arthritis, arthralgia, meningitis (weeks to months later)
    • Third stage: appearance of chronic arthritis (months to years later)
  11. Lab ID of B. burgdorferi
    • Can be cultured, but takes 6-8 weeks
    • Serological tests provide too many false-positives
    • Most definitive test is PCR assay
  12. Treatment and prevention of B. burgdorferi
    • Treatment with antibiotics.
    • If arthritic symptoms have appeared, longer courses of antibiotics are required
    • Prevention includes insect repellents, and proper clothing to protect from ticks
  13. Difference between endemic relapsing fever and epidemic relapsing fever
    • Endemic relapsing fever: (Lyme disease) caused by B. burgdorferi
    • Occurs in most areas of the world and is tickborn
    • Fatalities are rare
    • Epidemic relapsing fever: caused by B. recurrentis
    • Transmitted from human to human by body lice
    • Fatalities can be as high as 30% if untreated
  14. Describe symptoms caused by B. recurrentis.  What causes them?
    • High fever, severe headache, muscle pains for 3-5 days with abundant spirochetes in blood
    • Latent period (with no spirochetes in blood) for 4-10 days follows
    • Rinse/repeat up to ten times
    • Caused by the antigenic variation of B. recurrentis
  15. Diagnosis, treatment, and prevention of B. recurrentis
    • Diagnosis based on spirochetes in blood during fever portion of disease
    • Antibiotics are effective, but it is hard to tell difference between latency and cure
    • No vaccines are available
    • Protect against lice
  16. Describe the epidemiology of L. interrogans
    • A zoonosis which is coincidentally transmitted to humans by water or food contaminated with animal urine
    • Entrance to body via small skin abrasions or conjunctiva
    • Very rare in developed countries
  17. Describe the disease of L. interrogans
    • Leptospirosis
    • Fever occurs 1-2 weeks after infection, when spirochetes appear in blood, and decrease after a week
    • In biphasic disease spirochetes reappear and invade liver, kidneys, and CNS
    • This results in jaundice, hemorrhage, tissue necrosis, and/or aseptic meningitis
  18. Diagnosis, treatment, and prevention of L. interrogans
    • Diagnosis based on serologic agglutination tests and visual demonstration of spirochetes in blood, urine, or CSF
    • Antibiotics are effective during first stage, but ineffective at later stages
    • No vaccine is available
    • Prevention of exposure to contaminated water/food

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