title: The combination of ultrasound with antibiotics released from bone cement decreases the viability of planktonic and biofilm bacteria: an in vitro study with clinical strains.
abstract: OBJECTIVE
  Antibiotic-loaded bone cements are used for the permanent fixation of joint prostheses. Antibiotic-loaded cements significantly decrease the incidence of infection. The objective of this study was to investigate whether the viability of bacteria derived from patients with a prosthesis-related infection could be further decreased when antibiotic release from bone cements was combined with application of pulsed ultrasound.
  
  
  METHODS
  Escherichia coli ATCC 10798, Staphylococcus aureus 7323, coagulase-negative staphylococci (CoNS 7368 and CoNS 7391) and Pseudomonas aeruginosa 5148 were grown planktonically in suspension and as a biofilm on three different bone cements: Palacos R without gentamicin as control, gentamicin-loaded Palacos R-G and gentamicin/clindamycin-loaded Copal. The viability of planktonic and biofilm bacteria was measured in the absence and presence of pulsed ultrasound for 40 h.
  
  
  RESULTS
  Ultrasound itself did not affect bacterial viability. However, application of pulsed ultrasound in combination with antibiotic release by antibiotic-loaded bone cements yielded a reduction of both planktonic and biofilm bacterial viability compared with antibiotic release without application of ultrasound.
  
  
  CONCLUSIONS
  This study shows that antibiotic release in combination with ultrasound increases the antimicrobial efficacy further than antibiotic release alone against a variety of clinical isolates. Application of ultrasound in combination with antibiotic release in clinical practice could therefore lead to better prevention or treatment of prosthesis-related infections.
authors.affiliation: Department of Biomedical Engineering, University Medical Center Groningen, and University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.
authors.forename: Geert T
authors.initials: GT
authors.lastname: Ensing
authors.forename: Daniëlle
authors.initials: D
authors.lastname: Neut
authors.forename: Jim R
authors.initials: JR
authors.lastname: van Horn
authors.forename: Henny C
authors.initials: HC
authors.lastname: van der Mei
authors.forename: Henk J
authors.initials: HJ
authors.lastname: Busscher
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism* / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D001843:Bone Cements / Q000737:chemistry*; D002981:Clindamycin / Q000494:pharmacology; D015169:Colony Count, Microbial; D005839:Gentamicins / Q000494:pharmacology; D050296:Microbial Viability; D014465:Ultrasonics
chemical_list: D000900:Anti-Bacterial Agents; D001843:Bone Cements; D005839:Gentamicins; D002981:Clindamycin