Prevalence of bacterial burden on macroscopic contaminants of orthopaedic surgical instruments following sterilization

Abstract

Background: Macroscopic contamination of orthopaedic instruments with particulates, including cortical bone and polymethyl methacrylate (PMMA) bone cement, that have previously undergone pre-operative sterilization is frequently encountered peri- or intraoperatively, calling into question the sterility of such instruments.

Aim: To determine if macroscopic contaminants of orthopaedic surgical instrumentation maintain a bacterial burden following sterile processing, and to determine the most commonly contaminated instruments and the most common contaminants.

Methods: Macroscopic contaminants in orthopaedic instrument trays were collected prospectively at a single tertiary referral centre over a 6-month period from August 2021 to May 2022. When identified, these specimens were swabbed and plated on sheep blood agar. All specimens were incubated at 37 °C for 14 days, and inspected visually for colony formation. When bacterial colony formation was identified, samples were sent for species identification.

Results: In total, 33 contaminants were tested, and only one contaminant was found to be growing bacterial colonies (Corynebacterium sp.). The items most commonly found to have macroscopic contamination were surgical trays (N=9) and cannulated drills (N=7). The identifiable contaminants were bone (N=10), PMMA bone cement (N=4) and hair (N=4). Eleven macroscopic contaminants were not identifiable.

Conclusion: This study found that 97% of macroscopic orthopaedic surgical instrument contaminants that underwent sterile processing did not possess a bacterial burden. Contaminants discovered during a procedure are likely to be sterile, and do not pose a substantially increased risk of infection to a patient.

Keywords: Bacteria; Contaminant; Instruments; Orthopaedic; Sterility; Tools.