Related Experiment Video
Updated: Jun 2, 2026
A Periprosthetic Joint Candida albicans Infection Model in Mouse
Published on: February 2, 2024
Different microbial biofilm formation on polymethylmethacrylate (PMMA) bone cement loaded with gentamicin and
E Bertazzoni Minelli1, T Della Bora, A Benini
1Pharmacology Section, Department of Public Health and Community Medicine, University of Verona, Policlinico G.B. Rossi, P.le L.A. Scuro, 10, 37134 Verona, Italy. elisa.bertazzoni@univr.it
Abstract:
We studied the in vitro effects of gentamicin and vancomycin alone and in combination added to polymethylmethacrylate (PMMA) cement specimens on the bacterial adhesion of multiresistant clinical isolates. The PMMA specimens (discs) loaded with gentamicin (1.9%) or vancomycin (1.9%) or with a combination of the two were placed in Mueller-Hinton Broth inoculated with bacterial strains. After incubation, bacterial growth was determined by optical density (OD(540)) and sub-cultures. The biofilm PMMA-associated dye (crystal violet) was measured. Antibiotic concentrations in broth were determined by fluorescence polarisation immunoassay. All antibiotic-loaded PMMA cement specimens released high, inhibitory concentrations of gentamicin and vancomycin. However, differences in strain growth and adhesion were recorded. The clinical isolates Met-R/Gent-R CoNS showed no adhesion to gentamicin-loaded specimens for 24 h; strains with Gent-Intermediate susceptibility exhibited growth after 48 h but reduced adhesion. Some Gent-R strains exhibited growth and adhesion to antibiotic-loaded specimens similar to controls (plain discs). Only the VRSA strain (Staphylococcus aureus 5/7) and Escherichia coli were able to grow and adhere to vancomycin-loaded specimens after 24 h of incubation. The specimens loaded with the gentamicin + vancomycin combination showed a synergistic inhibitory effect against all tested strains (no bacterial growth). The degree of bacterial adhesion to PMMA cement loaded with gentamicin or vancomycin may be reduced in spite of a normal growth rate and is different for the tested strains. The effect of gentamicin and vancomycin on bacterial growth and adhesion to PMMA bone cement depends on the antibiotic concentrations, on the characteristics of each specific strain and on its ability to produce biofilm and adhere to antibiotic-loaded PMMA bone cement.
Insights
Gentamicin and vancomycin in polymethylmethacrylate (PMMA) cement effectively inhibit bacterial adhesion, with a combination showing synergistic effects against multiresistant strains.
Area of Science:
- Orthopedic surgery
- Infectious disease
- Biomaterials science
Background:
- Polymethylmethacrylate (PMMA) bone cement is widely used in orthopedic procedures.
- Multiresistant bacterial infections pose a significant challenge, often requiring antibiotic-eluting implants.
- Understanding antibiotic efficacy against bacterial adhesion to PMMA is crucial for preventing implant-associated infections.
Purpose of the Study:
- To evaluate the in vitro efficacy of gentamicin and vancomycin, alone and in combination, when incorporated into PMMA cement.
- To assess the impact of these antibiotic-loaded cements on bacterial adhesion and growth of multiresistant clinical isolates.
Main Methods:
- PMMA cement discs loaded with gentamicin, vancomycin, or both were prepared.
- Specimens were incubated with bacterial strains in Mueller-Hinton Broth.
- Bacterial growth (optical density, sub-cultures) and biofilm formation (crystal violet) were measured.
- Antibiotic concentrations in the broth were quantified using fluorescence polarization immunoassay.
Main Results:
- All antibiotic-loaded PMMA specimens released high, inhibitory concentrations of gentamicin and vancomycin.
- Gentamicin-loaded PMMA showed no adhesion for Met-R/Gent-R CoNS, reduced adhesion for Gent-Intermediate strains, and similar adhesion for some Gent-R strains compared to controls.
- Vancomycin-loaded PMMA allowed growth and adhesion of VRSA and E. coli strains.
- The gentamicin + vancomycin combination demonstrated synergistic inhibition, preventing bacterial growth against all tested strains.
Conclusions:
- Antibiotic-loaded PMMA cement can reduce bacterial adhesion and growth, but efficacy varies with antibiotic type, concentration, and bacterial strain characteristics.
- The combination of gentamicin and vancomycin exhibits a synergistic effect, offering superior inhibition of bacterial adhesion and growth.
- Strain-specific factors, including biofilm production and adhesion capabilities, influence the effectiveness of antibiotic-loaded PMMA bone cement.
