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Autoclaving Effectively Sterilizes Contaminated Retained Cement in Orthopaedic Surgical Trays
Andrew L Thomson1, Christina Chao1, Mohammad Hammad1
1Arthroplasty Research Laboratory, Research Institute, Hospital for Special Surgery, New York, NY.
Background:
Retained polymethylmethacrylate (PMMA) in surgical instrument trays and on instruments is becoming more common and is a disquieting situation for the arthroplasty operating room team. Although retained debris may be sterile after autoclaving, previous studies have not specifically investigated bacterial viability on retained PMMA. This study determined whether heavily contaminated PMMA surfaces and instruments covered in PMMA could be effectively sterilized by clinically utilized autoclaving protocols.
Methods:
Mature methicillin-susceptible Staphylococcus aureus (MSSA) and Escherichia coli biofilms were grown on PMMA coupons with a smooth surface (n = 5 per condition) or with deep crevices (n = 5 per condition) and on threaded screws, which were inserted into polymerizing PMMA (n = 5 per condition). PMMA coupons and PMMA-covered screws were subjected to 3 autoclave sterilization protocols. Colony-forming unit (CFU) counts and adenosine triphosphate (ATP) levels were measured to detect viable bacteria. Scanning electron microscope (SEM) images were obtained to determine whether biofilm was present.
Results:
Non-autoclaved PMMA surfaces were heavily contaminated, with values of 4.1 ± 2.3 × 10 6 CFUs/mL for S . aureus and 2.4 ± 1.2 × 10 6 CFUs/mL for E . coli. ATP levels of 3,230 ± 1,297 relative light units (RLU) for S . aureus and 1,006 ± 602 RLU for E . coli were observed. Crevices and screws were also heavily contaminated. Following autoclaving, CFUs/mL counts of <10 and RLU levels of <5 (beneath the hygienic threshold for cleanliness) were recorded on all PMMA surfaces, crevices, and screws. SEM confirmed that the biofilm structures remained intact, but they did not contain viable bacteria.
Conclusions:
PMMA and PMMA-covered instruments contaminated with gram-positive or gram-negative biofilms are effectively sterilized using clinical autoclaving protocols.
Clinical Relevance:
Retained PMMA and PMMA-covered surgical instruments that undergo a clinical autoclaving protocol do not carry viable bacteria.
Insights
Standard autoclaving effectively sterilizes polymethylmethacrylate (PMMA) and contaminated surgical instruments. This ensures that retained PMMA debris does not pose a risk of bacterial contamination in operating rooms.
Area of Science:
- Orthopedics
- Surgical Infection Control
- Biomedical Engineering
Background:
- Retained polymethylmethacrylate (PMMA) on surgical instruments is an increasing concern in arthroplasty.
- Previous studies have not confirmed bacterial viability on retained PMMA after autoclaving.
Purpose of the Study:
- To determine if clinical autoclaving protocols can effectively sterilize PMMA surfaces and instruments contaminated with biofilms.
- To assess bacterial viability on PMMA after standard sterilization procedures.
Main Methods:
- Biofilms of Staphylococcus aureus and Escherichia coli were cultured on PMMA coupons (smooth and crevice) and screws.
- Samples were subjected to three clinical autoclave sterilization protocols.
- Bacterial viability was assessed using colony-forming unit (CFU) counts and adenosine triphosphate (ATP) levels.
Main Results:
- Non-autoclaved PMMA showed high bacterial contamination (up to 4.1 x 10^6 CFUs/mL).
- Post-autoclaving, all PMMA surfaces, crevices, and screws showed negligible viable bacteria (<10 CFUs/mL and <5 RLU).
- Scanning electron microscopy confirmed biofilm structures remained intact but lacked viable bacteria.
Conclusions:
- Clinical autoclaving protocols are effective in sterilizing PMMA and PMMA-contaminated surgical instruments.
- Retained PMMA and instruments undergoing autoclaving do not harbor viable bacteria, ensuring surgical safety.
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