Spirochetes

• What is the main focus of the study material?

  Spirochetes and their clinical correlates
• What are the objectives of the study material?

  • Enumerate medically important members
  • Describe classification, cultural and microscopic characteristics
  • Discuss pathogenicity and virulence
  • Explain laboratory diagnosis
  • Review epidemiology
  • Outline treatment
• What shape do spirochetes typically have?

  Long, slender, helically coiled
• What structural feature produces the spiral shape in spirochetes?

  Presence of endoflagella or axial filaments
• Where are endoflagella located in spirochetes?

  In the periplasm, between membranes
• What are the characteristics of Treponema?

  • Family: Spirochaetaceae
  • Genus: Treponema
  • Width: about 0.2 µm
  • Length: 5-15 µm
  • Regularly spaced spirals (1 µm)
  • Replicates by transverse binary fission
• What microscopy technique is used for laboratory diagnosis of Treponema?

  Darkfield microscopy
• How do Treponema appear under darkfield microscopy?

  As motile, bright corkscrews
• What is the challenge in culturing Treponema?

  Difficult to culture continuously
• What medium is used to culture Treponema?

  Sf1Ep rabbit epithelial cells in TpCM-2
• What do treponemal tests detect?

  Presence of antibodies against Treponema
• What are nontreponemal tests used for?

  Screening for possible syphilis infection
• What do nontreponemal tests detect in the blood?

  Presence of cardiolipin or reagin IgE antibodies
• Why are nontreponemal tests not specific for syphilis?

  They may be positive in other conditions
• What are the laboratory diagnosis methods for Borrelia?

  • Brightfield microscopy with Giemsa stain
  • Serology tests (EIA or IFA)
  • Checks for antibodies against B. burgdorferi
  • Confirmed using immunoblot assay
• What are the characteristics of Leptospira?

  • Family: Leptospiraceae
  • Genus: Leptospira
  • Length: 5-15 µm
  • Tightly coiled, flexible spirochetes
  • One end often bent, forming a hook
• What medium is used to culture Leptospira?

  Ellinghausen-McCullough-Johnson-Harris (EMJH)
• What is the optimal growth condition for Leptospira?

  Aerobic conditions at 28-30 °C
• What is the appearance of Leptospira growth in culture?

  Dinger’s ring or disk
• What are the clinically important spirochetes mentioned?

  • Treponema (T. pallidum)
  • Leptospira (L. interrogans)
  • Borrelia (B. burgdorferi, B. recurrentis)
• What are the pathogenic species of Treponema?

  • T. pallidum subspecies:
  • pallidum (venereal disease)
  • pertenue (yaws)
  • endemicum (endemic syphilis)
  • T. carateum (pinta)
• What is the mode of transmission for T. pallidum?

  Sexual contact
• What are the stages of syphilis caused by T. pallidum?

  • Primary syphilis
  • Secondary syphilis
  • Tertiary syphilis
• What characterizes primary syphilis?

  Hard chancres or painless ulcers
• How long do lesions from primary syphilis typically last?

  6 to 8 weeks
• What are the symptoms of secondary syphilis?

  Mucocutaneous lesions and lymph node inflammation
• What percentage of patients may develop symptoms in secondary syphilis?

  Around 25%
• What is a common manifestation of tertiary syphilis?

  Neurosyphilis and cardiovascular syphilis
• What is congenital syphilis associated with?

  Hutchinson’s triad in neonates
• What are the potential outcomes of congenital syphilis?

  • Abortion or stillbirth
  • Hutchinson’s triad at birth
• What is the historical treatment for syphilis?

  • Penicillin
  • No transposable elements = low antibiotic resistance
• What is a potential characteristic of untreated syphilis?

  It may become latent syphilis
• What is the causative agent of syphilis?

  Treponema pallidum
• What is tertiary syphilis?

  Most invasive and severe form of syphilis
• When can tertiary syphilis manifest?

  After months, years, or decades post-infection
• What percentage of untreated patients may develop tertiary syphilis?

  Around 25% to 40%
• How does tertiary syphilis present?

  Varies depending on the affected organ
• What is the most common manifestation of tertiary syphilis?

  Cardiovascular syphilis
• What is congenital syphilis?

  Transplacental transmission of syphilis
• Is congenital syphilis usually contagious?

  No, usually not contagious