CLS 1113 Introduction to Clinical Laboratory Practices

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CLS 1113Introduction to Clinical Laboratory
Practices

• Unit 7
• Serological Diagnosis of Infectious Diseases

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Syphilis

• Treponema pallidum (Spirochete)
• Helically coiled - Cork-screw motility
• Have no natural reservoir in the environment
• Must multiply within a living host
• Difficult to isolate in the laboratory
• Transmission sexual or congenital
• 50,000 cases per year per your textbook
• http//www.cdc.gov/nchstp/dstd/Fact_Sheets/Syphili
  s_Facts.htm

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Spirochete Image
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Syphilis

• T. pallidum
• rapidly destroyed by heat, cold, and drying out.
• Sexual transmission
• 1/3 of individuals

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Syphilis - Staging

• Primary Stage
• Initial lesion - chancre, develops from 10 90
  days post infection. The lesion is painless.
• The lesions usually occur on the external
  genitalia, can also appear on the cervix, vagina,
  inside the mouth and the rectum.

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Syphilis

• Secondary Stage
• If untreated, ¼ of cases will progress to the
  secondary stage.
• The is characterized by the systemic
  dissemination of the organism.
• Lymphadenopathy, malaise, fever, pharyngitis,
  skin rash, etc.
• Skin lesions will last up to 8 weeks, but
  relapses can occur up to 4 years

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Syphilis

• Latent Stage
• Patients are non-infectious
• Patients lack clinical symptoms
• Occurs around 1 year post-infection

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Syphilis

• Tertiary Stage
• Usually occurs 10-30 years after the secondary
  stage
• Patients exhibit neurological, cardiac and
  cutaneous involvement
• Large skin lesions
• Degeneration of the spinal cord
• Mimics meningitis
• Destruction of elastic tissue of the Aorta

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Congenital Syphilis

• Syphilis passes from mother to child
• Can occur starting at 18 weeks gestation
• 2800 cases in 1990
• http//www.cdc.gov/mmwr/preview/mmwrhtml/mm5027a1.
  htm
• 40 mortality rate
• Bone, neural, and cutaneous abnormalities

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Immune Response

• Primary Defense
• Intact skin and mucous membranes
• What is the primary defense against STD?
• Secondary Defense
• T cells, macrophages, and antibody production

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Testing

• Direct detection
• Darkfield microscopy
• Fluorescent Antibody Testing

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Testing

• Non-Treponemal Serological Tests
• Rapid Plasma Reagin (RPR) and Venereal Disease
  Research Laboratory (VDRL) Tests
• Tests detect the presence of reagin, an
  antibody against cardiolipin (lipid molecule).
• Reagin antibodies
• IgG or IgM
• Also found in other diseases
• RPR-Antigen Suspension containing charcoal
  particles