According to a scientific study published in the December print publication of the American Journal of Infection Control (AJIC), 87 percent of tested sterilized rigid containers – used in the sterilization of surgical instruments – allowed ingress of aerosol-ized bacteria under the test condi-tions used. This study calls into question the assumption that rigid containers, regardless of duration of use, can maintain the sterility of their contents post-sterilization.

Approximately 300,000 surgical site infections (SSIs) occur annually in U.S. hospitals, resulting in an estimated 9,000 attributable deaths. Maintaining a sterile environment in the operating room (OR) is essential for SSI prevention and may be achieved through the use of sterile packaging systems (SPS). SPS are designed to protect surgical instruments post-sterilization until use in the OR. The two primary types of SPS include rigid contain-ers and sterilization wrap. Rigid

containers are reusable and come in a variety of materials (various metals, aluminum and polymers) and sizes, while single-use steriliza-tion wrap is often composed of polypropylene.

The study, “Sterility Maintenance Study: Dynamic Evaluation of Sterilized Rigid Containers and Wrapped Instrument Trays to Prevent Bacterial Ingress,” used a dynamic aerosol test method that allowed for air exchanges to occur in SPSs that may simulate normal air exchanges in hospital settings. The study found that:

• Rigid containers, both used and unused, failed to maintain barrier performance under these test conditions: 87 percent (97 out of 111) of the rigid containers failed to maintain barrier performance, allowing ingress of the challenge microorganism.

Rigid containers may be less effective the longer they are in use: Contamination rates of rigid containers increased as durationof use increased.

• Rigid containers with 5-9 years of use were signifi cantly more likely to have bacterial ingress than unused rigid containers (p = 0.04).

Sterilization wraps provided no detectable ingress of bacteria: 100 percent (161 out of 161) of the wrapped trays using sterilization wrap maintained barrier perfor-mance, preventing any bacterial ingress and protecting sterility.

The study was conducted by Harry L. Shaff er of Sterilization Consulting Services LLC, High-lands Ranch, Colorado; Reid A. Vernon of the United States Air Force Academy, Colorado Springs, Colorado; and Delbert Harnish, Michael McDonald and Brian K. Heimbuch of Applied Research Associates, Panama City, Florida.

The study was funded by Halyard Health (formerly Kimberly-Clark Health Care).