Persisting bacteria survive antibiotic treatment in lab culture. Here, the authors showed that antibiotics killed most of lab-grown B. burgdorferi, with a small surviving population that tolerated drug treatment. They found that mitomycin C, a cancer drug, efficiently killed persisters. They also showed how pulse-dosing, wherein four repetitive cycles that included treating bacterial cultures with ceftriaxone, followed by washing out the drug, resulted in eradication of persistent bacteria.