we observed that
BcepIL02 delivered to the apical cell surface did not penetrate
the intact epithelium (data not shown). It is also possible that
the lower phage titers we observed in infected lungs after intraperitoneal
injection (relative to phage titers after inhalation)
reflect a more rapid decrease in bacterial density and the subsequent
clearance of phage in the absence of sufficient bacterial
hosts [34]. Finally, we found no significant differences between
any of the treatment or control groups in the density of bacteria
recovered from spleens of infected mice (data not shown). Although
it is possible that systemic phage may have greater access
to such extrapulmonary sites than do intranasal phage, this
finding suggests that bacterial reinfection of lung from infected
spleen does not account for the differences in lung bacterial
density observed between groups.