Because Burkholderia species typically are nonpathogenic in
animals, studies investigating the virulence of these species often
employ the agar bead model of respiratory infection, where
bacteria are embedded in agar beads prior to instillation into
murine lungs [31]. Animals develop nonlethal pulmonary disease,
and viable bacteria may be recovered from lungs for 2–
3 weeks. However, because phage killing depends on unobstructed
access of phages to their bacterial target, we chose to
employ a model of acute infection that avoids encasing bacteria
in agar. In a series of preliminary experiments, we determined
that when inoculated into the lungs of mice via intratracheal
instillation, B. cenocepacia causes nonlethal pulmonary disease
and can be recovered for up to 7 days, thus providing a tractable
model to assess the relative efficacy of anti-infective treatments.
We also chose to use B. cenocepacia strain AU0728, which was
recovered from respiratory culture of a patient with cystic fibrosis,
and is a representative of the B. cenocepacia Midwest clone,
a lineage that accounts for a great deal of infection among patients
with cystic fibrosis in the United States [32]. Furthermore,
our previous work with AU0728 indicates that it is multidrugresistant
and capable of robust biofilm formation in vitro (unpublished
data) and thus ought to provide for a rigorous test
of novel anti-infective therapies.