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 x 10(6)) 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 degrees C. Direct enumeration of survivors was performed to evaluate IR death. Instrument loads contained carriers laden with spores (1.06 +/- 0.3 x 10(6)). The spores were seeded on tryptic soy agar and survivors were counted after 120 hours of incubation at 37 degrees 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.

Biologic monitoring of dental office sterilizers in Mexico.

BACKGROUND: Biologic indicators (BIs) are the quality control applicable to sterilization cycles, but their use was not previously taught in Mexican dental schools or recommended by professional associations. A Mexican official standard, the Mexican Official Norm, published by health authorities in 1999 makes it compulsory for dentists to biologically verify sterilization cycles. However, only a few dentists comply because the use of BIs is largely unknown and the standard is not being enforced. OBJECTIVE: To evaluate the incidence of sterilization failures in a convenience sample of dental offices in Mexico. METHODS: Spore strips were distributed to dentists interested in using this service. The dentists mailed the processed BIs to the laboratory for culture. RESULTS: In 6 years, 3277 tests were submitted from 82 dental offices. Thirty-four offices (41%) submitted 1 to 12 tests, 22 (27%) sent 14 to 48 tests, 18 (22%) mailed 49 to 96 tests, and 8 (10%) sent >97 tests. The sterilization methods were steam (74.4%), dry heat (20%), and chemical vapor (5.6%). A total of 242 sterilization failures (7.4% of all cycles) were detected. Convection dry heat failed with a greater frequency with chi(2) analysis (chi(2) = 13.71, P =.0175). CONCLUSIONS: Sterilization failures occurred in instrument loads used in patient treatment. Steam and chemical vapor under pressure failed less often than convection dry heat. When corrective action is taken, routine use of BIs increases patient safety.