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Published on: March 3, 2023
Pre-sterilization of vancomycin-loaded cement spacers: impact on antibacterial efficacy against Staphylococcus aureus
Kulapat Chulsomlee1, Pisut Pongchaikul2, Rungroj Sadchaphaiboonkit1
1Chakri Naruebodindra Medical Institute, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
Background:
Antibiotic-loaded polymethylmethacrylate (PMMA) cement spacers are widely used in periprosthetic joint infection and chronic osteomyelitis. Manual prefabrication and sterilisation of non-commercial antibiotic-loaded cement may reduce operative time and cost; however, the effects of sterilisation and storage on antimicrobial efficacy remain unclear.
Methods:
Manually prefabricated PMMA cement containing vancomycin (2 g or 4 g) underwent formaldehyde gas sterilisation (FO) and storage for one, four or seven days. Antibiotic elution was evaluated over 28 days. Antimicrobial activity against Staphylococcus aureus ATCC 25923 was assessed using minimum inhibitory dilution (MID) testing at predefined time points. Given the small number of specimens per subgroup, all comparisons should be interpreted as preliminary and hypothesis-generating.
Results:
FO sterilisation significantly reduced antimicrobial activity during the early elution phase. In the 4-g vancomycin group, Day 1 MID values were significantly higher in one day storage sterilised specimens than in specimens stored for four or seven days (1024 µg/mL vs. 213 µg/mL and 213 µg/mL, respectively; P < 0.001). Differences persisted at early time points but were no longer significant during the sustained elution phase (Days 14-28; P > 0.05). Overall, sterilised cement containing 4 g of vancomycin demonstrated higher MID values than 2 g cement during the early and mid-elution phases (Days 1-14; P < 0.01). MID values in all sterilised specimens remained several-fold above inhibitory thresholds for S. aureus throughout the 28-day period.
Conclusions:
FO sterilisation transiently reduces vancomycin antimicrobial activity during the early elution phase (Days 1-7) but does not affect sustained antimicrobial efficacy compared with non-sterilised cement. Based on these findings, vancomycin-loaded PMMA cement containing 4 g of antibiotic may be sterilised and stored for up to seven days while maintaining MIC values several-fold above inhibitory thresholds for Staphylococcus aureus throughout the 28-day elution period.
Insights
Formaldehyde gas sterilization of vancomycin-loaded polymethylmethacrylate (PMMA) cement temporarily reduces early antimicrobial activity but maintains efficacy against Staphylococcus aureus over 28 days, even after seven days of storage.
Area of Science:
- Orthopedics
- Infectious Diseases
- Materials Science
Background:
- Antibiotic-loaded polymethylmethacrylate (PMMA) cement spacers are crucial for treating periprosthetic joint infections and chronic osteomyelitis.
- Manual prefabrication and sterilization of PMMA cement can reduce operative time and costs.
- The impact of sterilization and storage on the antimicrobial efficacy of PMMA cement remains unclear.
Purpose of the Study:
- To evaluate the effects of formaldehyde gas sterilization and storage duration on the antimicrobial efficacy of vancomycin-loaded PMMA cement.
- To determine if manual prefabrication and sterilization are viable methods for clinical use.
Main Methods:
- Polymethylmethacrylate (PMMA) cement loaded with vancomycin (2g or 4g) was prefabricated and sterilized using formaldehyde gas (FO).
- Specimens were stored for one, four, or seven days.
- Antibiotic elution was measured over 28 days.
- Antimicrobial activity against Staphylococcus aureus was assessed using minimum inhibitory dilution (MID) testing.
Main Results:
- Formaldehyde gas (FO) sterilization significantly reduced early antimicrobial activity, with higher Day 1 MID values observed in specimens stored for longer durations.
- These differences in antimicrobial activity diminished during the sustained elution phase (Days 14-28).
- Specimens with 4g vancomycin showed higher MID values than those with 2g during the early and mid-elution phases, and all sterilized specimens maintained efficacy above inhibitory thresholds for S. aureus throughout the 28-day period.
Conclusions:
- Formaldehyde gas (FO) sterilization transiently reduces vancomycin antimicrobial activity in PMMA cement during the initial elution phase (Days 1-7).
- Sustained antimicrobial efficacy is not compromised by sterilization and storage for up to seven days.
- Vancomycin-loaded PMMA cement (4g) can be sterilized and stored for up to seven days, maintaining significant antimicrobial activity against Staphylococcus aureus.
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