Abstract
Ethylene oxide (EO) is one of the most important sterilizing agents for heat and moisture-sensitive materials. Strings for surgical sutures were exposed to EO/nitrogen (N2) gaseous mixtures at defined process conditions and biologically monitored by Bacillus subtilis spores, inoculated on strips. The study aimed to determine the best relation between logarithmic spore reduction (SLR) of B. subtilis spores and process parameter range: EO concentration, from 138 mg/L to 301 mg/L; exposure temperature from 45 °C to 72 °C and exposure time from 50 min to 150 min.

For 138 mg/L of EO, the average SLR rose from 4.55 to 9.36 at 45 °C and from 5.98 to 10.08 at 72 °C, respectively on increasing the exposure time from 50 min to 150 min. For 301 mg/L of EO, the average SLR of 10.78 for 50 min decreased slightly to 9.36 for 150 min exposure time, at 72°C. The EO concentration range from 138 mg/L to 301 mg/L for 150 minutes at 45 °C was equivalent to 301 mg/L of EO for 50 min at 45 °C and for 150 minutes at 72 °C. The EO at 138 mg/L for 150 min corresponded to 301 mg/L for 50 min at 72 °C, the parameters of which guaranteed lethality levels greater than 10-4 in relation to B. subtilis logarithmic spore reductions. Furthermore, the physical integrity of the surgical suture strings was preserved, thus guaranteeing safe and effective usage.
 

Abstract
Alkaline detergents have been widely used as detergents for medical use. Especially, enzymatic detergents containing protease demonstrate a strong detergent action within a neutral area, and they have the advantage of being less damaging to equipment and devices. For that reason, the use of enzymatic detergents containing protease has been rapidly spreading in recent years. Although protease is an enzyme that can decompose protein such as blood powerfully, protease itself is quite unstable. When detergents containing protease were stored at 4 °C or 40 °C for 161 days, the protease activity in the detergent stored at 4 °C was unchanged, while that stored at 40 °C was decreased by 38 %. Likewise, when a 1.0 % diluted detergent solution (normal concentration) was kept at 37 °C, the protease activity was almost halved from the 2nd day to the 3rd day. In addition, when protease activities of 9 different types of protease containing enzymatic detergents (1.0 % diluted detergent solutions) were measured, they showed wide variations ranging from 2,000 U/L to 70,000 U/L. When the relationship between protease activity and detergent action was examined by using concentrations of adenosine triphosphate (ATP) derived from blood as an indicator, the amount of protease required for a 1.0 % diluted detergent solution was assumed to be approximately 50,000 U/L.