Borrelia burgdorferi
One-Sentence Definition
Borrelia burgdorferi sensu lato spirochetes are tick-transmitted agents of Lyme disease in North America/Europe — causing early localized, disseminated, and late musculoskeletal/neurologic/cardiac manifestations.
Taxonomy & Morphology
- Spirochaetaceae; spiral bacteria; microaerophilic
- Related: B. recurrentis (relapsing fever), Treponema pallidum
Virulence Highlights
- Migration through skin and tissues
- Immune evasion (variable surface proteins)
- Tick (Ixodes) vector — coinfection with other tick agents possible (ehrlichia, babesia — context)
Clinical Syndromes
- Erythema migrans (pathognomonic early)
- Disseminated: facial palsy, meningitis, carditis, migratory arthralgias
- Late Lyme arthritis (US pattern)
Diagnosis
- Clinical EM often sufficient in endemic areas
- Serology two-step (EIA → Western blot) — interpret by timing (Serology in Clinical Microbiology)
- PCR on EM biopsy early; CSF PCR limited sensitivity
Treatment Notes (conceptual)
- Doxycycline, amoxicillin, ceftriaxone by stage/system involvement
- Prophylaxis after tick bite — selective per guidelines
Related Notes
Active Recall
- Early localized hallmark lesion?
- Why two-step serology?
- Vector genus?