Effect of rifabutin and tigecycline combination on M. abscessus viability. The following antibiotics were added to M. abscessus ATCC 19977 cultures: rifabutin at 1× (6.3 mg/liter), 1/2×, or 1/4× MIC (A); tigecycline at 1× (0.8 mg/liter), 1/2×, or 1/4× MIC (B); or a combination of rifabutin and tigecycline at 1×, 1/2×, or 1/4× MIC of each antibiotic (C). CFU were determined at 24-h intervals after antibiotic addition. Data points are the means from three replicates with standard deviations presented as error bars.