Low-temperature sterilization methods can often fail to completely sterilize surgical tools, according to a new study published in Infection Control & Hospital Epidemiology, the journal of the Society for Healthcare Epidemiology of America.
One such method, vaporized hydrogen peroxide (VHP), failed to completely sterilize tools 76% of the time when the tools were soiled with salts or blood and not cleaned prior to sterilization, the study found.
“While sterilization technology is capable of killing billions of microorganisms on instruments, some low temperature processes are unintentionally undermined when surgical instruments are improperly cleaned before sterilization,” said William A. Rutala, PhD, MPH, director of the North Carolina Statewide Infection Control and Epidemiology Program, in a release.
Researchers at the University of North Carolina at Chapel Hill tested the effectiveness of three low-temperature technologies, often used for plastic tools, against steam sterilization by simulating the impact of proteins and salts left on tools before sterilization. Stainless steel test carries were used to simulate surgical tools; researchers soiled them with salt and blood and contaminated them with common bacteria found in healthcare settings such as Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, vancomycin-resistant Enterococcus, among others.
The equipment was then sterilized using VHP, ethylene oxide (ETO), hydrogen peroxide gas plasma (HPGP), or steam. VHP had the highest failure rate at 76.3%, followed by HPGP and ETO with 1.9%. Steam sterilization, the most common technique for sterilization of heat-resistant instruments, had no failures.
“If instruments are not properly cleaned prior to sterilization and then placed in a low-temperature sterilization technology such as vaporized hydrogen peroxide, there is a possibility of failure,” Rutala said. “Effectively cleaning, removing visible soil and microbial contaminants from objects, must precede sterilization to ensure tools are thoroughly and optimally sterilized.”
Cleaning complex medical equipment, such as surgical instruments and endoscopes with hinges, sharp bends, and lumens, presents a special challenge for cleaning and sterilization, the researchers said. Another challenge is naturally occurring biofilm build-up on medical and surgical instruments, they added.