Borrelia burgdorferi (Lyme Disease)

5,098 views

Bacteria - Gram Negative

Borrelia burgdorferi

Characteristics
- Spirochete (spiral-shaped with axial filaments)
  - Doesn’t gram-stain well due to thin cell walls
Transmission
- Common in northeastern US
  - Often in patients who do outdoor activities (hiking, camping) in northeast US
- Transmitted by the Ixodes tick
  - Also a vector for Anaplasma spp. and Babesia; coinfection is common
  - Natural reservoir is the mouse
Lyme disease
- Stage 1 – localized
  - flu-like symptoms
  - Erythema migrans ("bulls-eye" or “target” lesion)
    - Expanding ring-shaped erythematous rash that begins 1-2 weeks around site of bite
- Stage 2 – early disseminated
  - Occurs weeks to months after inoculation without treatment
  - “FACE” mnemonic: facial nerve, arthralgias, cardiac block, erythema migrans
  - Facial nerve (Bell) palsy
    - Extremely rare presentation of Lyme disease
  - Migratory arthralgias
    - Transient migratory joint pain
  - Heart block (AV block)
    - Due to Lyme carditis and localized inflammation in conductive tissue of heart
- Stage 3 – late disseminated
  - Occurs months or years after inoculation without treatment
  - Encephalopathy
  - Chronic arthritis (knees)
Diagnosis
- Visualized by dark-field microscopy, or direct fluorescent antibody (DFA) microscopy
- Can use ELISA to detect serologic immunoglobulins
Treatment
- Doxycycline (1st line)
- Amoxicillin (and ceftriaxone if severe illness – CNS signs or heart block)
- Macrolides
  - Second line in those who are allergic to first line