Sensitivity of Borrelia and Leptospira to Quinupristin-dalfopristin (Synercid) in vitro.

In vitro activity of Quinupristin-dalfopristin (Synercid) against seventeen isolates of Borrelia burgdorferi and two representatives of Leptospira spp. was investigated. MICs ranged from 0.03 to 0.125 for B. burgdorferi and 0.125-0.25 microg/ml for Leptospires. Time killing studies carried out with 2 MIC demonstrated U 3 log(10)-unit killing after 72 h, showing a significant activity against spirochetes, though at a lower level than other antibiotics in use in the therapy of Lyme disease and leptospirosis.