It is easy to kill bacteria - what is much harder is doing so without significant toxicity to the host. And there is no mention in the PR of even animal tox data.
The PR says the drug won't be ready for the clinic until 2014 so presumably those safety studies still remain to be completed in 2013. Galapagos does note that the target of the drug is absent in humans. Presumably that may bode well for safety in that there may be a wider safety window and less risk of off-target effects; perhaps not, as other issues could arise of course.