Validating sporicidal efficacy of ultrasound probe high-level disinfection devices in clinical settings

IntroductionIn accordance with AS5369:2023 and ISO 15883-1:2024 Standards, in-field validation testing of automated high-level disinfection (HLD) devices in clinical settings is necessary to qualify their performance. Responding to reports that some ultraviolet-C (UV-C) devices were failing to achieve sporicidal efficacy during routine in-field validation, we evaluated the sporicidal efficacy of these devices via a performance qualification test. MethodsSporicidal efficacy was assessed using commercially available stainless steel biological indicators (BIs) inoculated with 106 Geobacillus stearothermophilus spores (ATCC(R) 7953). BIs were clamped in top and bottom locations inside chambers of devices [UV-C light-emitting diode (LED), UV-C lamp and hydrogen peroxide (H2O2) mist]. BI test conditions included packaged, unwrapped and non-flamed and unwrapped and flame sterilised on the clamped coupon end. Results were evaluated on a pass (no growth) or fail (growth) basis. ResultsThe results showed that the UV-C LED device failed to inactivate spores in all tested positions and conditions (n=18). The UV-C lamp device passed 2/6 tests in the flamed condition but failed all other tests (n=12). The H2O2 mist system passed all tests, inactivating spores for all conditions and chamber positions (n=18). ConclusionOur findings show that despite claiming sporicidal efficacy, the UV-C devices both failed in-field validation tests using bacterial endospores. These results indicate that the UV-C devices were not sporicidal in these tests. The H2O2 mist device was the only system in this study that passed all tests, achieving sporicidal efficacy.