- More difficult to cure, also significant drug resistance.
- Need DUAL abx! Use ampicillin + ceftriaxone for synergy (in the past, often amp + gent, but now often use CTX b/c of toxicities a/w gent, and studies show CTX works just as well) x6 weeks
- MOA: CTX saturates the beta-lactam receptors on bacterial cell walls, allowing for more ampicillin killing of the bacteria. So cool!
- Ixodes tick bite on for >24 hours!!
- Clinical manifestations/treatment: 3 phases
- 1) early localized (erythema migrans) à can treat with po doxycycline (10-21 days)
- 2) early disseminated (acute neuro or cardiac involvement weeks to months after tick bite) à generally, IV ceftriaxone for 28 days
- 3) late (arthritis, encephalopathy, polyneuropathy, years after) à IV CTX, cefotaxime, or PCN G for 28 days if CNS involvement
- When to get serologies: Two-tier testing with ELISA followed by Western blot for Borrelia burgdorferi
- +endemic area/exposure to ticks, +compatible sxs
- NO serologies if:
- erythema migrans rash – may be too early and serologies may be negative
- Screening of asx pts, non-specific sxs (fatigue, myalgias/arthralgias) – low pre-test probability and high false positive rate!