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Impact of polymethylmethacrylate additives on methicillin-resistant Staphylococcus pseudintermedius biofilm formation
Shauna Morrison1, Ameet Singh, Joyce Rousseau
1Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.
Objective:
To evaluate the impact of gentamicin, silver, or both additives in polymethylmethacrylate (PMMA) beads on methicillin-resistant Staphylococcus pseudintermedius (MRSP) biofilm formation in vitro.
Sample:
4 preparations of PMMA beads (formed with no additive [control], gentamicin, silver, and gentamicin and silver).
Procedures:
Beads from each group were exposed to 10 MRSP isolates known to be strong biofilm formers. Following incubation, the beads were rinsed to remove planktonic bacteria, then sonicated to dislodge biofilm-associated bacteria. Resulting suspensions were serially diluted, plated on blood agar, and incubated overnight; CFUs were counted. Variance of mean CFU counts following log10 transformation was analyzed among PMMA groups.
Results:
None of the PMMA additives tested completely inhibited MRSP biofilm formation. There was a significant effect of gentamicin and gentamicin plus silver on this variable, compared with controls, but not of silver alone. There was no difference between gentamicin and gentamicin plus silver. When only isolates not susceptible to gentamicin were evaluated, there were no significant differences among PMMA additive groups. Within gentamicin-susceptible isolates, there was an impact of gentamicin and gentamicin plus silver, but no impact of silver alone and no difference between gentamicin and gentamicin plus silver.
Conclusions And Clinical Relevance:
Gentamicin-impregnated PMMA was effective at reducing biofilm formation of gentamicin-susceptible MRSP isolates but had no effect on isolates not susceptible to gentamicin. Silver-impregnated PMMA had no effect on MRSP biofilm formation. Results suggested that gentamicin-impregnated PMMA may not be effective in vivo against MRSP isolates not susceptible to gentamicin. Antibacterial efficacy of silver should not be assumed without proper testing of the target bacteria and specific silver compound.
Insights
Gentamicin-impregnated polymethylmethacrylate (PMMA) beads reduced methicillin-resistant Staphylococcus pseudintermedius (MRSP) biofilm formation in vitro, but only for gentamicin-susceptible strains. Silver additives showed no effect on MRSP biofilm.
Area of Science:
- Biomaterials Science
- Microbiology
- Infectious Diseases
Background:
- Methicillin-resistant Staphylococcus pseudintermedius (MRSP) poses a significant challenge due to its ability to form biofilms.
- Polymethylmethacrylate (PMMA) beads are used in orthopedic implants and can be impregnated with antibiotics to prevent infections.
- Evaluating the efficacy of antibiotic-loaded PMMA against MRSP biofilms is crucial for improving treatment outcomes.
Purpose of the Study:
- To assess the in vitro efficacy of PMMA beads containing gentamicin, silver, or both, against MRSP biofilm formation.
- To determine if the presence of gentamicin or silver in PMMA influences MRSP biofilm development.
- To compare the effects of gentamicin-alone, silver-alone, and combined gentamicin-silver PMMA beads on MRSP biofilm.
Main Methods:
- Four types of PMMA beads were prepared: control (no additive), gentamicin, silver, and gentamicin plus silver.
- Beads were exposed to 10 different MRSP isolates known for strong biofilm formation.
- Biofilm formation was quantified by counting colony-forming units (CFUs) after sonication and serial dilution.
Main Results:
- No PMMA additive completely inhibited MRSP biofilm formation.
- Gentamicin and gentamicin-plus-silver PMMA significantly reduced biofilm formation compared to controls.
- Silver alone did not significantly impact MRSP biofilm formation; no difference was observed between gentamicin and gentamicin-plus-silver groups.
Conclusions:
- Gentamicin-impregnated PMMA effectively reduced biofilm formation in gentamicin-susceptible MRSP isolates.
- Gentamicin-impregnated PMMA showed no efficacy against gentamicin-non-susceptible MRSP isolates.
- Silver-impregnated PMMA demonstrated no effect on MRSP biofilm formation, and its in vivo efficacy cannot be assumed without specific testing.
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