Sterilization of Heat-Resistant Instruments With Infrared Radiation

Objective:To evaluate the lethality profile of an infrared radiation (IR) prototype sterilizer.Method:Simulated use and D value tests were conducted with Bacillus subtilis spores American Type Culture Collection–9372. A spore suspension (1.06 ± 0.03 × 106) in 5% bovine serum albumin was air dried on stainless steel instruments. IR cycles were completed and the instruments were immersed in tryptic soy broth for 120 hours at 37°C. Direct enumeration of survivors was performed to evaluate IR death. Instrument loads contained carriers laden with spores (1.06 ± 0.3 × 106). The spores were seeded on tryptic soy agar and survivors were counted after 120 hours of incubation at 37°C.Results:All instruments exposed to IR (n = 50) were culture negative. In contrast, all unprocessed instruments (n = 30) showed B. subtilis growth. The prototype's D value was 0.56, and the death rate's slope was -1.76 (r = -0.99741; P < .0001). The 10-6 sterility assurance level was reached after 8 minutes and 40 seconds of exposure, from cold start.Conclusions:IR destroys B. subtilis spores. Instrument sterilization with IR may provide another technology for infection control.