Figure 5. Streptococcus mitis strains cause dose-dependent disease in mice with neutropeniaA) Multilocus sequence analysis–generated neighbor-joining tree showing genetic relationships among all Smitis strainsBold branches indicate locations of the 5 strains used in the mouse model challenge experimentNumbers 1–3 refer to clusters of Smitis strains (defined in Figure 3)Scale bar indicates genetic distanceB) Example of mouse challenge dataTen neutropenic Balb/C mice per dose were infected intraperitoneally with serial 10-fold CFU dilutions of strain SVGS004 (range 10⁷–10³) and monitored for 168 h (7 d) for near-death statusPhosphate buffered saline (PBS) was injected as a controlNone of the mice injected with PBS or with the 10³ dose were near death; thus, the 1 × 10³ line is obscured by the PBS line on the graphSVGS, Shelburne viridans group streptococcus.