Tedizolid is highly bactericidal in the treatment of pulmonary Mycobacterium avium complex disease

Objectives: To determine if tedizolid is effective for pulmonary Mycobacterium avium complex (MAC) disease, and to use pharmacokinetics/pharmacodynamics to design optimal doses. Methods: We performed an exposure-response experiment in the hollow-fibre system model of intracellular MAC (HFS-MAC). We mimicked the tedizolid concentration-time profiles achieved in the lungs of patients treated once daily for 28 days. The HFS-MAC was sampled at intervals to determine the tedizolid pharmacokinetics and MAC intracellular burden. We identified the 0-24 h area under the concentration-time curves to MIC (AUC(0-24)/MIC) ratios associated with the following targets: 80% of maximal kill (EC80), bacteriostasis, and 1.0 and 2.0 log(10) cfu/mL kill. We then performed 10000 patient Monte Carlo simulations to identify the optimal dose for each of the exposure targets. Results: Tedizolid achieved the feat of 2.0 log10 cfu/mL kill below initial bacterial burden, an effect not seen before in this model with other antibiotics. The tedizolid exposure associated with 1.0log(10) cfu/mL kill was a non-protein bound AUC(0-24)/MIC ratio of 23.46, while that associated with 2.0 log(10) cfu/mL kill was 37.50, and the EC80 was 21.71. The clinical dose of 200mg achieved each of these targets in similar to 100% of the 10000 patients, except the 2.0 log(10) cfu/mL kill which required 300mg/day. A tedizolid susceptibilityMIC breakpoint of 1mg/L is proposed. Conclusions: Tedizolid, at standard clinical doses, is expected to be bactericidal, and even achieved an unprecedented 2.0 log(10) cfu/mL kill of MAC as monotherapy. We propose it as the backbone of short-course anti-MAC chemotherapy.