FIG 1.
Rifabutin kills M. abscessus in mice. (A) Kinetics of bacterial burden in lungs and spleen of M. abscessus K21-infected NOD.CB17-Prkdcscid/NCrCrl mice. The inoculum of 106 CFU was delivered intranasally. At designated time points, lungs and spleens of 4 animals were homogenized and plated on agar for CFU determination. (B) Schematic representation of the murine M. abscessus lung infection model used in this study. (C and D) Animals infected with M. abscessus K21 underwent drug treatment for 10 consecutive days. Drugs were administered once daily by oral gavage to groups of 6 mice per study group. At 11 days postinfection, organ homogenates were plated on agar to determine the bacterial load. Results were analyzed using one-way analysis of variance (ANOVA) multicomparison and Tukey’s posttest. *, P < 0.05; **, P < 0.01; ***, P < 0.001. MICs reducing growth of M. abscessus K21 by 90% over 3 days for clarithromycin (CLR), rifampin (RIF), and rifabutin (RFB) were 0.6 μM, 50 μM, and 2.4 μM, respectively. CFU kinetics was carried out twice, and the drug efficacy study was done three times. Representative data sets are shown.