The efficacy of the STERISAFE technology is demonstrated on a test microorganism (Enterococcus faecium) in real-life conditions. The test was performed in a hospital patient room to replicate real-life conditions.

Healthcare-associated infections (HAI) are infections acquired in healthcare facilities, notably hospitals. They can have tremendous financial, medical and emotional consequence for anyone involved; and with the emergence of antibiotic-resistant bacteria, to the society in general. Unfortunately, due to their very nature and the presence of often immune-weakened patients, hospitals are extremely prone to HAI occurrences. There is an ongoing effort to prevent such infections, with the ultimate goal to eradicate them.

While proper personal hygiene routine from patients, employees and visitors are essential to prevent HAI, poorly sanitized surfaces are a considerable risk for infections. Frequent and thorough disinfection is needed in every nook and cranny of healthcare facilities. However, it is often difficult and impractical to do so in some places. For example, patient rooms in hospitals contain many hard-to-reach corners, high places, or behind-furniture locations that are potentially great breeding grounds for pathogens. Airborne-disinfection systems are a practical way to address this issue. Such system includes the STERISAFE PRO from STERISAFE, which uses automated room decontamination technology using ozone gas to treat a given sealed area, such as a hospital patient room.

The scientists Knobling, Kostenkow and Knobloch (2018) from the University Medical Center Hamburg-Eppendorf (UKE) tested a STERISAFE PRO unit, going beyond the strict requirements of the NF T 72-281 standard. While this standard evaluates airborne disinfection systems under harsh efficacy passing grades in terms of pathogen kill-rate, it only does so in unfurnished standardized rooms. To replicate the real-life conditions under which the STERISAFE PRO is supposed to operate, Knobling et al. tested its disinfection efficiency in a hospital patient room, complete with furniture, an integrated bathroom and a vestibule.

Efficacy was tested by preparing ceramic tiles pre-contaminated at high levels with a test pathogen. Those tiles were scattered in hospital patient rooms at diverse locations: they could be inside furniture or out in the open, and placed on the ground, or at mid- or high-level (see Figure below for more details). The STERISAFE PRO was operated as per intended use, using a maximum ozone concentration of 80 ppm for a dwell time of 60 minutes at 90% relative humidity, giving a total disinfection cycle lasting about 150 minutes. This test was repeated 5 times, with the tiles placed at the same locations and pre-contaminated at the same levels.

The test microorganism used for the study was an innocuous strain of Enterococcus faecium, which in its pathogenic form can cause various infections such as endocarditis. E. faecium is also known for its antibiotic-resistant strain commonly referred to as Vancomycin-resistant Enteroccocus (VRE), and a leading cause of HAI in the world. Over their 5 replicates, Knobling et al. demonstrated an average of above 99.999% kill-rate of E. faecium in the test hospital room, irrespective of the location of the test surface. This result corresponds to a log-reduction of 5.1, which is above the minimum kill-rate required for bacteria under the NF T 72-281 standard.

This test demonstrates the efficacy of the STERISAFE PRO for E. faecium under complex real-life conditions, where a significant pathogenic reduction was achieved even in traditionally hard-to-reach areas of patient hospital rooms.  The use of STERISAFE technology can be extended to healthcare spaces other than patient rooms. In general, airborne disinfection is potentially adequate for any area with cleaning challenges, where high levels of disinfection are required but traditional cleaning by hand or aqueous media is insufficient.

ADDITIONAL NOTE: Variations of the same test were later performed on other organisms (Acinetobacter baumanii and Candida auris) with success.

With courtesy of Knobling et al. DGKH (2018)

Reference: Knobling B., Kostenchow T. & Knobloch J.K.M. (2018). Standardised test of the disinfection efficiency of room disinfection with ozone under complex room conditions.