In vivo infection models vary significantly in their pathophysiology and severity. We initially demonstrated activity of MyxA in the mouse model of P. multocida sepsis. Mice were treated with single doses of 10 mg/kg (i.p.) or 50 mg/kg (s.c.) MyxA 1 h post-infection. Strikingly, although blood levels of MyxA at 30 min and 2 h after administration did not exceed in vitro MICs, the compound was highly effective in reducing the bacterial burden in liver and significantly increasing survival rates when administered i.p. (Fig. ). Interestingly, although blood levels after s.c. administration of 50 mg/kg were higher than in the group receiving the 10 mg/kg i.p. dose, the latter treatment was much more successful and bacteriological cure was achieved for five out of six animals.