Microbial Diseases Lecture Notes

Introduction to Spirochetes

• Spirochetes: Helical bacteria characterized by their spiral shape.
  • Size: Thin and long, ranging from 0.1-3 micrometers in diameter and 5-250 micrometers in length.
  • Cell Wall: Gram-negative with an outer sheath composed of lipid, carbohydrate, and protein.
  • Axial Filament: Also known as periplasmic or endoflagella, enclosed within the outer sheath.
  • Movement: Endoflagella rotation results in the rotation of the outer sheath, propelling the cell through its medium.

Structure of Spirochetes

• Visual representation and detailed structure analysis (refer to accompanying slide image).

Pathogenic Spirochetes

• Two significant spirochetes causing diseases in the U.S.:
  • Treponema pallidum:
    • Causative agent of syphilis.
    • Syphilis is a sexually transmitted disease with 200,000 cases per year in the U.S. as of 2022.
    • Congenital syphilis is acquired in utero with approximately 3,500 cases per year in the U.S.
  • Borrelia burgdorferi:
    • Causative agent of Lyme disease.
    • Zoonosis transmitted by the tick vector.

Borrelia burgdorferi and Lyme Disease

• Characteristics:
  • Relatively large spirochete measuring 0.2 by 10-30 micrometers.
  • Difficult to grow in culture due to a slow generation time of 10-12 hours.
• Transmission:
  • Vector: Ixodes tick, commonly known as the deer tick.
  • Reservoir: White-footed mouse.
• Prevalence:
  • Significant epidemic in the U.S. with 60,000 cases per year.
  • Most prevalent in the Northeast and Pacific Coast of the U.S.

Additional Notes

• The presentation consists of 74 slides focusing on microbial diseases.
• Further exploration of different microbial diseases is expected in subsequent slides.