Sterile Water (sWFI) as Negative Control for Sterility - (Mar/14/2012 )
I don't see any real reason not to use water for negative control, as long as it's sterile. WFI isn't all that kind to bacteria, osmotically. But definately preferred would be the same media you're using for the rest of the testing if its sterile just so you eliminate one more factor.
Injection in what?
It can have an influence.. so it all depends on whether it an influence your animals or whatever you are going to inject.