Sterility maintenance study: Dynamic evaluation of sterilized rigid containers and wrapped instrument trays to prevent bacterial ingress.
BACKGROUND
Sterilized packaging systems are designed to maintain the sterility of surgical instruments and devices from the time of sterilization until use. This study evaluated the effectiveness of rigid containers versus wrapped instrument trays, sterilized using North American sterilization protocols, to maintain a sterile internal environment poststerilization when challenged with aerosolized bacteria under dynamic environmental conditions.


METHODS
Using a custom aerosol chamber, 111 rigid containers of various durations of use (unused, used <5 years, used 5-9 years) and 161 wrapped trays using 3 grades of sterilization wrap were challenged with ~10(2) colony-forming units per liter of air containing aerosolized Micrococcus luteus with a count median particle size of 1 μm, while simultaneously experiencing air volume exchanges due to vacuum cycles-two 1-psi cycles, three 0.7-psi cycles, and three 0.4-psi cycles-to simulate air exchange events occurring during the sterilization, transportation, and storage of sterilized instrument trays in health care facilities.


RESULTS
Of 111 rigid containers tested, 97 (87%) demonstrated bacterial ingress into the container. Of 161 wrapped trays, 0 (0%) demonstrated bacterial ingress into the tray. Contamination rates of rigid containers increased significantly with increasing duration of use.


CONCLUSIONS
In this study using a dynamic bacterial aerosol challenge, sterilized wrapped trays demonstrated significantly greater protection than sterilized rigid containers against the ingress of airborne bacteria.
Sterilization Consulting Services, LLC, Highlands Ranch, CO. Electronic address: shafferscs@gmail.com.
Harry L
HL
Shaffer
Engineering Science Division, Applied Research Associates, Panama City, FL.
Delbert A
DA
Harnish
Engineering Science Division, Applied Research Associates, Panama City, FL.
Michael
M
McDonald
United States Air Force Academy, Colorado Springs, CO.
Reid A
RA
Vernon
Engineering Science Division, Applied Research Associates, Panama City, FL.
Brian K
BK
Heimbuch
D000336:Aerosols; D050456:Fomites; D016982:Micrococcus luteus / Q000302:isolation & purification; D009656:North America; D019064:Product Packaging / Q000379:methods; D013242:Sterilization; D013523:Surgical Equipment / Q000382:microbiology*
D000336:Aerosols
Bacterial contamination; Microbial barrier; Rigid container; Sterility maintenance; Sterilization; Sterilization wrap; Surgical site infection; Surgical tools