Evolving strategies for preventing biofilmon implantable materialsSHAH RS, TATARA AM, D’SOUZA RN, MIKOS AG, & KASPER FK

Background Many implants are exposed to site bacteria

Biofilm allows bacteria to increase antibiotic resistance and escape immune responses

Biofilm contains mostly polysaccharide chains and extracellular DNA

The polysaccharide network prevents the effects of antibiotics on the bacteria

The persister theory offers a mechanism that explains why biofilm infections recur

Biofilm producing bacteria stained with crystal violet

Past Attempts: working with materialsFor dental implants, surface roughness, implant morphology, and material used has been found to have little impact on biofilm formationMaterial choice is significant for orthopedic implants, PMMA as the most sensitive to bacterial colonization and titanium as the least◦ Antibiotic-loaded PMMA beads coating the implant surface harbor bacteria

Vancomycin HCL Tobramycin sulfate

Culture media surrounding these constructs is rendered sterile by eluted antibiotics (circled areas indicate where culture media was spot-plated on an agar plate)

Present Attempts: local delivery of antibiotics

Collagen sponges have good flexibility, coverage, and biocompatibility ◦ releases most of the antibiotics too quickly

Calcium sulfate is resorbable and has osteoconductive properties◦ autologous bone grafts are convenient

Degradable polymer matrices , namely PLA and PLGA:◦ provide controlled release ◦ preserve the drug’s bioactivity◦ release almost all of the drug

Future Approaches: PreventionD-amino acids are good dispersal agents due to low-cost and high potency

Bacteriophages can lyse bacteria and disrupt the biofilm

Some surface coatings resist biofilm and have anti-adhesive properties

Coating the implants with bacteria that lack the virulence for an infection prevents adhesion of biofilm

Conclusions and Significance As knowledge of biofilms has grown, new methods of dealing with implant-associated infections have evolved

Presently, as we treat biofilms with antibiotics, resistance is increasing

Approaches that are necessary for current antibiotics to stay effective, such as◦ Competition using non-virulent species◦ Using agents that bacteria already synthesize◦ Synthetic materials◦ Bacteriophages