Sterilization of B. Atropheaus Cotton Threads and Polyester Sutures Using Supercritical Carbon Dioxide with Hydrogen Peroxide Additive

Sterilization
of biomedical devices and biomaterials is required prior to invasive surgical
procedures.  The FDA defines sterilization as 6-log (99.9999%) reduction of
bacterial spores.  This project examines the killing of B. atrophaeus
spores inoculated on typical fibrous biomaterials, i.e. cotton threads and
polyester sutures. Both substrates were treated with supercritical CO₂
with trace levels of H₂O₂.  The sterilization process was
also tested with the polyester sutures placed inside a 1/8-inch diameter lumen
(tube), representative of an endoscope.  Treated substrates were assayed for
killing efficiency using a pour plating technique.  We can claim at least 5.24-log
reduction of spores on cotton threads, and 4.55-log reduction of spores on polyester
sutures.  However, turbidity tests of treated threads and sutures showed no
growth of spores after 24-hours, indicating a complete spore killing.  Sutures
treated within a 2 foot lumen indicated 4.24-log kill; additional replication
of results is required.  B. atrophaeus threads and sutures can be used in future work to test
sterilization by securing substrates within biomedical devices, and sterilizing
the devices using SC-CO₂ + H₂O₂.