Not sure my post said anything about killing them? the real problem with a biofilm, is changing the terrain though. biofilms are strong enough to survive industrial solvents... once we put ourselves in this stage, no easy way out. even knowing whether they are gone is extremely difficult. can lie dormant for years protected in the biofilm, dormant and totally safe from the immune system. with no cell wall, you immune system doesn't even know that they are there.