The Biofilm Problem
Bacterial infections of the bone are generally considered very difficult to treat and can be cured only with great effort. The reason that conventional antimicrobial therapies often fail, is the formation of so-called "biofilms" on the surface of dead bone areas or foreign bodies such as implants. Numerous bacteria are capable of forming such biofilms. Once these germs make contact with poorly perfused bone or said foreign bodies, they usually require only a few hours to convert from the free-living planktonic to the adherent sessile form, producing a kind of slime sheath. Within this protective environment, they slow their growth and are largely cut off from most environmental conditions, including the effect of immune cells and antibiotics.
Free-living (planktonic) bacteria can be killed by antibiotics and the immune system. Adherent bacteria, however, survive within the biofilm since they are vulnerable only to extremely high doses of antibiotics, which cannot be achieved by systemic administration.
For years germs protected by the above mentioned microfilm often cause only minor or no symptoms at all, but then for reasons unknown become active again.
Several studies have now demonstrated that these bacterial films are much more common than previously thought and frequently may be the cause of "aseptic" loosening of implants, but also for not clearly identifiable symptoms (Culture Negative Orthopedic Biofilm Infections).