In vitro testing of chitosan in gentamicin-loaded bone cement: no antimicrobial effect and reduced mechanical performance.
OBJECTIVE
Efforts to prevent infection of arthroplasties, including the use of antibiotic-loaded bone cement, are not always successful. We investigated whether the incorporation of chitosan in gentamicin-loaded bone cement increases antibiotic release, and prevents bacterial adherence and biofilm formation by clinical isolates of Staphylococcus spp. In addition, we performed mechanical and degradation tests.


METHODS
Different amounts of chitosan were added to the powder of the gentamicin-loaded bone cement. Gentamicin release was determined using high-per-formance liquid chromatography mass spectrometry. Bacterial adherence and bacterial biofilm formation were determined using clinical isolates cultured from implants retrieved at revision hip surgery. The mechanical properties were determined as a function of degradation in accordance with ISO and ASTM standards for PMMA bone cement.


RESULTS
The addition of chitosan to bone cement loaded with gentamicin reduced gentamicin release and did not increase the efficacy of the bone cement in preventing bacterial colonization and biofilm formation. Moreover, the mechanical performance of cement containing chitosan was reduced after 28 days of degradation. The compressive and bending strengths were not in compliance with the minimum ISO and ASTM requirements.


CONCLUSIONS
Clinically, incorporation of chitosan into gentamicin-loaded bone cement for use in joint replacement surgery has no antimicrobial benefit and the detrimental effect on mechanical properties may have an adverse effect on the longevity of the prosthetic joint.
Dunne
Nicholas
N
Schools of Mechanical and Aerospace Engineering, Belfast, UK. n.dunne@qub.ac.uk
Buchanan
Fraser
F
Hill
Janet
J
Newe
Caroline
C
Tunney
Michael
M
Brady
Aaron
A
Walker
Gavin
G
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D019643:Arthroplasty, Replacement / Q000009:adverse effects; D001422:Bacterial Adhesion / Q000187:drug effects*; D018441:Biofilms / Q000187:drug effects*; D001843:Bone Cements; D048271:Chitosan; D005839:Gentamicins / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D016459:Prosthesis-Related Infections / Q000517:prevention & control; D013210:Staphylococcus / Q000187:drug effects; D013314:Stress, Mechanical
D000900:Anti-Bacterial Agents; D001843:Bone Cements; D005839:Gentamicins; D048271:Chitosan