Spirochetes

• Spirochaetaceae family


  Spiral bacteria
• Taxonomy of Spirochetes


  • Order Spirochetales
  • Genus Treponema
  • Genus Borrelia
  • Genus Leptospira
  • Spirochaetaceae family
  • Leptospiraceae family
• Spirochetes


  • Long and thin bacteria, spiral shaped
  • Extremely mobile, very flexible
  • All have axial filaments that act as an intracellular propeller
  • HIGH MOBILITY
• Metabolism of Spirochetes


  Microaerophilia, anaerobic
• Some species of Spirochetes can be cultivated in the lab, most cannot
• Habitat of Treponema


  • Humans are the only natural hosts
  • There are commensal treponemas in the oral cavity
  • Species of medical interest - Treponema pallidum (3 subspecies)
• Routes of transmission for Treponema pallidum

  1. Unprotected sexual intercourse

  2. Direct contact with moist secretions at the lesion site

  3. Through the placenta
• Syphilis


  • Infectious disease with the potential to become chronic (can last 8-10 years)
  • Evolves in 3 phases: Primary, Asymptomatic, Secondary, Asymptomatic, Tertiary
• Types of Syphilis


  • Genital syphilis
  • Congenital syphilis
• Syphilis lesions


  • Chancre lesion on the lower lip
  • Penian chancre
  • Oral chancre
  • Syphilitic roseola (rash)
  • Condiloma lata
  • Syphilitic gumma
• Congenital Syphilis


  • Extended central nervous system lesions (mental retardation)
  • Liver and spleen enlargement
  • Rash and fever
  • Saddle nose deformation
  • Numerous cutaneous and ocular lesions
  • Oral cavity anomalies
• Dental defects in congenital syphilis

  • Hutchinson's incisors
  • Moon's molars
  • Fournier's molars

  
• Laboratory diagnosis of syphilis

  1. Sample collection: exudate, lymph node, organ biopsy, blood, CSF, umbilical cord blood, placental tissue, nasal secretion

  2. Microscopic examination: wet mount, dark field microscopy, fluorescence microscopy, Giemsa stain, Fontana-Tribondeau stain

  3. Isolation on culture media (not done for diagnostic purposes)

  4. Serological diagnosis: non-treponemal tests, treponemal tests

  
• Non-treponemal tests


  Low specificity, use a mixture of cardiolipin, cholesterol, lecithin as antigen, used for screening, become negative after clearance of infection
• Treponemal tests


  High specificity, use Treponema pallidum extracts as antigen, used for confirmation, remain positive for life
• False-positive reactions may appear in non-treponemal and treponemal tests in various conditions
• VDRL test


  Easy, convenient screening test, becomes positive 7-10 days after appearance of chancre lesion, useful for screening and monitoring treatment
• TPHA test


  Passive hemagglutination reaction, used as confirmation test, can be used semi-quantitatively to determine antibody titre
• Treatment of syphilis


  Penicillin G intramuscular is the preferred antibiotic, erythromycin or tetracycline in case of penicillin allergy
• Aggressive treatment with penicillin can cause Jarish Herxheimer reaction
• There is no vaccine for syphilis, prevention is through safe sex practices
• Borrelia


  • Strictly parasitic spirochetes, have 3-10 free spirals, 'L' shaped extremity, largest diameter, can be cultivated on acellular media, microaerophilic
• Habitat of Borrelia


  Natural reservoir is Ixodes ticks, transmitted from animals to humans (zoonosis)
• Borrelia recurrentis


  Aetiological agent of epidemic recurrent fever, transmitted by lice
• Borrelia burgdorferi complex


  Transmitted by Ixodes ticks, causes Lyme disease
• Lyme disease


  Infectious disease with articular, neuronal, cardiac muscle tropism, transmitted by ticks infected with Borrelia burgdorferi complex, progresses in 3 stages
• MPLEX


  Transmitted by ticks from the Ixode family (hard ticks)
• Borrelia species in MPLEX

  • B. burgdorferi sensu stricto
  • B. garinii
  • B. afzelii
  • B. spielmanii
• LYME DISEASE


  Infectious disease that has articular, neuronal, cardiac muscle tropism transmitted to humans by ticks infected with species from Borrelia burgdorferi Complex
• Stages of Lyme Disease

  1. Early LOCALISED stages

  2. Early DISEMINATED stages

  3. LATE DISEMINATED stages
• NOT ALL ticks are infected [around. 35% of them]
• Stages of Lyme Disease

  1. Primary - Expanding area of redness at tick bite site (erythema migrans), rash is neither itchy or painful

  2. Secondary - Arthritis, meningitis, cranial nerve paralysis, heart palpitation, fever, headaches, memory loss

  3. Tertiary - Severe cardiovascular and neuronal manifestations, possibility of developing cerebral tumors
• Migratory rash


  BULLs EYE appearence
• Laboratory Diagnosis of Lyme Disease

  1. Sample collection

  2. Microscopic examination

  3. Isolation of Borrelia
• Microscopic examination


  Wet mount, Dark field microscopy, Stained smear, Fluorescence microscopy
• Isolation of Borrelia


  1. In vivo - Intraperitoneal injection in rats

  2. In vitro - Barbaour-Stoenner-Kelly culture media, Incubation conditions, Identification
• Fluorescence microscopy


  Staining technique - acridine orange, Observe spirochetes in patient/lab animal blood
• Indirect diagnosis - Serology

  ELISA test, Western-blott test, Advantages of new diagnosis algorithm
• Treatment


  Doxicicline, Penicilin G, Ceftriaxone, Early treatment prevents late neurologic complications
• There is no VACCINE available !!