evolving strategies for preventing biofilm on implantable materials
Post on 23-Feb-2016
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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
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