Solithromycin MIC and Disk Diffusion Quality Control Ranges, a CLSI Multi-Laboratory M23-A3 Study Design

• For AD testing, all (100.0%) reported MIC results would be in the proposed limits of 0.03 – 0.25 µg/mL for solithromycin. The “shoulder” at 0.06 µg/mL represents 80.5% of the modal 0.12 µg/mL MIC value. Therefore, a four log 2 dilution range was proposed for the MIC QC range using the CLSI M23-A3 criteria (Figure 1). No significant skewing of results and modal MIC values was observed among media lots or laboratories; all of the observed solithromycin AD modal MIC values were within one doubling dilution of 0.12 µg/mL. • Ciprofloxacin was used as an antimicrobial control agent, and all MIC values were within the CLSI published QC range (0.001-0.008 µg/mL), therefore providing a validated internal control for this study (Table 2).