Spirochetes

• How many genera of spirochetes cause human infection?


  Three
• What is the genus of spirochetes that causes syphilis?

  Treponema
• Which spirochete causes Lyme disease?

  Borrelia
• What disease is caused by Leptospira?


  Leptospirosis
• What are the diseases caused by the three genera of spirochetes?


  • Treponema: Syphilis and nonvenereal treponematoses
  • Borrelia: Lyme disease and relapsing fever
  • Leptospira: Leptospirosis
• What are the modes of transmission for the diseases caused by spirochetes?


  • T. pallidum (Syphilis): Intimate contact; across the placenta
  • B. burgdorferi (Lyme disease): Tick bite
  • B. recurrentis (Relapsing fever): Louse bite
  • L. interrogans (Leptospirosis): Contaminated food or drink
• What is the morphology of T. pallidum?


  Thin, tight spirals
• How is T. pallidum diagnosed?


  Microscopy and serologic tests
• What is the treatment for T. pallidum infection?


  Penicillin G
• What is the mode of transmission for B. burgdorferi?


  Tick bite
• What is the treatment for Lyme disease?

  Tetracycline or amoxicillin for acute; Penicillin G for chronic
• What is the morphology of B. recurrentis?


  Large, loosely coiled
• What is the treatment for B. recurrentis infection?


  Tetracycline
• How is L. interrogans transmitted?


  Through food or drink contaminated by urine of infected animals
• What is the morphology of L. interrogans?


  Thin, tight spirals
• What is the treatment for leptospirosis?


  Penicillin G
• How do spirochetes move?


  Through the undulation of axial filaments that lie under the outer sheath
• What microscopy techniques are used to see spirochetes?


  Darkfield microscopy, silver impregnation, and immunofluorescence
• What is a key property of Treponema pallidum?


  Has not been grown on bacteriologic media or in cell culture
• How is Treponema pallidum transmitted?


  From spirochete-containing lesions of skin or mucous membrane of an infected person
• Where does Treponema pallidum infect in the body?


  Small blood vessels
• What are the clinical findings of primary syphilis?


  A local nontender ulcer (chancre) usually forms in 2-10 weeks
• What are the clinical findings of secondary syphilis?


  Maculopapular rash, moist papules, and patchy alopecia
• What is latent syphilis?


  A stage where no lesions appear but the infection continues
• What is the difference between early and late latent syphilis?


  Early can last for a year or two after secondary stage; late can last for many years with no symptoms
• What are the clinical findings of tertiary syphilis?


  May show granulomas (gummas) and CNS involvement
• What is congenital syphilis?


  Transmitted across the placenta, typically after the 3rd month of pregnancy
• What is the immunity status in Treponema pallidum infections?


  Immunity is incomplete; antibodies do not stop disease progression
• What are the laboratory diagnosis methods for Treponema pallidum?


  1. Microscopy
  2. Nonspecific serologic test
  3. Specific serologic test
• What microscopy techniques are used for laboratory diagnosis of T. pallidum?


  Darkfield microscopy and direct fluorescent antibody test
• What are nonspecific serologic tests for T. pallidum?


  Tests that involve nontreponemal antigens, such as VDRL and RPR
• What does a positive nonspecific serologic test indicate?


  Positive in most cases of primary and secondary syphilis
• What is the prozone phenomenon in serologic testing?


  A false negative result that happens if the titer of antibody is too high
• What are specific serologic tests for T. pallidum?


  Tests that involve the use of treponemal antigens, such as FTA-ABS and TPHA
• What does a positive specific serologic test indicate?


  Remains for life even after effective treatment
• What is the effective treatment for all stages of T. pallidum infection?


  Penicillin
• What is the Jarisch-Herxheimer reaction?


  A reaction experienced by >1/2 of patients with secondary syphilis treated with penicillin, causing fever and chills
• What are the prevention strategies for T. pallidum infections?


  • Early diagnosis and adequate treatment
  • Use of condoms
  • Administration of antibiotics after suspected exposure
  • Serologic follow-up of infected individuals and their contacts
• What is the status of vaccine development for syphilis?


  There is no vaccine
• What are the nonvenereal treponematoses?

  • Infections caused by spirochetes indistinguishable from T. pallidum
  • Endemic in some populations
  • Transmitted by direct contact
  • Positive results on serological tests
  • All can be cured by Penicillin