Phagolysosomal ROS production within KCs controls intracellular MRSA replication. (a) Stitched image of mouse livers by SD-IVM from WT and ROS-deficient Cybb^−/− mice at 8 h after i.v. infection with MRSA (MW2-GFP; green). Bar, 250 µm. Quantification of Staphylococcal accumulation in the liver (c) 15 min and (b) 8 h after infection in WT, MPO^−/−, CatC^−/− iNOS^−/−, Ncf1^m1j, and Cybb^−/− mice. Sum of MRSA-GFP fluorescence calculated from 2 mm² stitched liver images. n = 4 per group. Error bars, SEM. *, P < 0.05; ***, P < 0.001, versus WT by one-way ANOVA with Bonferroni’s posttest. (a–c) Data were pooled from two independent experiments. (d) Survival of MRSA (MW2)-infected WT mice or Cybb^−/− mice. n = 5 mice per group; log-rank test. (e) Staphylococcal accumulation in liver and kidney 24 h after i.v. infection with MRSA (MW2) in WT or Cybb^−/− mice measured by CFU. n = 4 per condition. *, P < 0.005; **, P < 0.01, Student’s t test. SD-IVM imaging of in vivo ROS production. (f) WT mice infected with oxidation-reporter MRSA (MW2 labeled with AF647 (blue) and OxyBURST (green). White arrow heads indicate MRSA that have been oxidized. Yellow arrowheads show MRSA where no oxidation was detected. Images were taken at 5 and 30 min after infection (Video 5). (g) Percentage of intracellularly oxidized MRSA within KCs over time. Data represent mean of five separate FOV, per time point. n = 4 mice. Error bars, SEM.