Retained bioburden does not pose contamination risk after a full sterile processing cycle

Introduction After sterile processing, orthopedic instrument trays are occasionally found to have retained bone from prior procedures. This study aims to assess the effect on heavily contaminated bioburden, adjacent tray, and instrument contamination risk of a standard medical facility sterile processing cycle for orthopedic instruments. Methods Porcine bone was placed in a wire mesh basket and inoculated with Geobacillus Stearotherophilus (G. stearothermophilus). This was then processed in the standard manner at our medical center, placed into unwrapped trays, and then into a multi-tray sterilization container (Turbett Sterilization Pod) for autoclave sterilization. The study was conducted at a private laboratory specializing in certification of sterile processing, Highpower ValidationTesting and Lab Services, Rochester ,N.Y.(Highpower).The steps of processing included an initial soak, ultrasonic cleaning, rinse, automated wash cycle, and steam sterilization. Following this, all test samples were placed into culture medium and incubated for seven days. Results There were no positive test samples following completion of the standard sterile processing steps. These included 36 samples of inoculated bone, 72 samples of simulated adjacent instruments, and 36 spore indicator strips. Conclusions This is the first investigation to the authors knowledge that examines bone bioburden in the context of a standard full sterile processing sequence. Similar prior studies have focused on the autoclave only efficacy. This study suggests that bone bioburden that has been through the full sequence of sterile processing is not contaminated and does not cross contaminate adjacent instruments or trays. The methodology used most closely replicated the scenario of freely exposed bone bioburden.