Compliance to hand-hygiene guidelines in healthcare facilities remains disappointingly low for a variety of human-factors (HF) reasons. A device HF-engineered for convenient and effective use even under high-workload conditions could contribute to better compliance, and consequently to reduction in healthcare-acquired infections. We present an overview of the efficacy of a passive hand-spray device that uses solubilized ozone —a strong, safe, non-irritant biocide having broad-spectrum antimicrobial properties—on glass surface, pigskin, and synthetic human skin matrix.
Reported incidents of healthcare-associated infection (HAI) have declined from nearly 2 million annually in the United States to about 800,000 despite similar or greater patient load [
Because ozone is a strong oxidizing biocide that has broad-spectrum antimicrobial properties [
The device (
A series of tests were performed on various carrier/microbe combinations comparing different ozone stream delivery methods at varying ozone concentrations. The tests showed the relative contributions of the spray action and the ozone reactivity to the antimicrobial effect, and they demonstrated the efficacy against a range of microbes.
Testing was performed using 0.8 ppm ozone water concentration (above the minimum required to act as a disinfectant) delivered at a rate of 0.5 GPM (gallons per minute) using a laminar flow water delivery. Glass slide carriers (cleaned using 95% ethanol prior to rinsing with reverse osmosis water and then autoclave sterilized) were challenged with seven microbe strains with an inoculum that ranged from 1 to 5 × 105 CFU/carrier. Each carrier was placed under the ozonated water stream at a distance of 6 inches. Three exposure durations were examined: 10, 15, and 30 sec. Ten samples were used for each test.
Testing compared water alone with two levels of ozone concentration (0.7 and 0.9 ppm) and two water delivery methods (3D fluidics spray and laminar flow). Staphylococcus aureus was chosen as the test pathogen (prepared in Tryptic Soy Broth and incubated at 36˚C for ~18 hours) and pigskin was chosen as a surrogate for human skin. The pigskin was cut into 1-inch squares and sterilized (by soaking in 95% ethanol for 20 min, then rinsed 3 - 5 times with sterile reverse osmosis water and placed into paper lined petri dishes at ambient temperature until visibly dry. Once dry, carriers were exposed to germicidal UV light for 10 minutes for added sterilization.). The inoculum (0.01 mL of 1:10 culture) was distributed across each pigskin carrier at an inoculum ranging from 5 to 7 at concentration approximately 5 × 105 CFU/carrier. Each carrier was placed under the water stream during the test at a distance of approximately 6 inches at a 45-degree angle. Three durations were examined: 10, 30, and 60 sec with five samples for each test.
VITRO-SKINÒ (IMS Inc., Portland, ME) is an advanced synthetic substrate formulated to have characteristics similar to human skin. Testing compared water alone with an ozone concentration of 0.8 ppm. S. aureus was chosen as the test organism. The sterile substrate was cut into 4 × 4 inch square carriers, which were inoculated with 0.1 mL of a 1:10 culture. The inoculum was spread evenly over the surface of the carrier. Once dry, each carrier was placed under the water stream at a distance of approximately 6 inches at a 45-degree angle. Three durations were examined: 5, 10, and 20 sec with five samples for each test. The carrier was moved in a circular motion through the ozonated water stream. Ozonated water remained in contact with the carrier for the entire duration of the contact time. At the conclusion of the contact time, the carrier was neutralized in 20 mL D/E broth. Neutralized carriers were vortex mixed for 2 minutes and plated using standard dilution and plating techniques. Plates were incubated for ~24 to 48 hours at 36˚C ± 1˚C.
The results are summarized in
| Organism | Straina | Classification | 10 sec Log Kill | 15 sec Log Kill | 30 sec Log Kill |
|---|---|---|---|---|---|
| Staphylococcus aureus (control) | 25923 | Gram-pos. bacteria | 4.16 | >4.57 | 4.57 |
| Staphylococcus aureus (MRSA) subsp. Aureus Rosenbach | BAA-44 | Gram-pos. bacteria | 4.55 | >3.85 | 4.55 |
| Staphylococcus epidermis (CoNS)― (Winslow and Winslow) Evans | 12228 | Gram-pos. bacteria | 3.47 | >3.11 | 3.91 |
| Enterococcus faecium (Orla-Jensen) Schleifer and Kilpper-Balz | 6569 | Gram-pos. bacteria | 4.83 | >4.87 | 4.87 |
| Enterococcus faecaelis (Andrews and Horder) Schleifer and Kilpper-Balz | 49532 | Gram-pos. bacteria | 3.93 | >4.11 | 4.11 |
| Candida albicans (Robin) Berkhout | 14053 | Diploid fungi | 4.00 | >4.00 | 4.00 |
| Clostridium difficile serogroup F | 43598 | Endospore | 1.26 | 1.61 | 3.17 |
| Ozone (ppm) | Delivery (0.5 GPM) | Straina | Classificationa | 10 sec Log Kill | 30 sec Log Kill | 60 sec Log Kill |
|---|---|---|---|---|---|---|
| 0.9 | Spray― 3D Fluidics | 6538 | Gram-pos. bacteria | 2.87 | 2.99 | 3.78 |
| 0.7 | Spray― 3D Fluidics | 6538 | Gram-pos. bacteria | 2.38 | 2.54 | 2.86 |
| 0.9 | Laminar | 6538 | Gram-pos. bacteria | 0.99 | 1.33 | 1.70 |
| 0.7 | Laminar | 6538 | Gram-pos. bacteria | 1.23 | 1.31 | 1.58 |
| 0.0 | Spray― 3D Fluidics | 6538 | Gram-pos. bacteria | N/A | N/A | 2.00 |
| 0.0 | Laminar | 6538 | Gram-pos. bacteria | N/A | N/A | 0.95 |
| Ozone (ppm) | Delivery (0.5 GPM) | Straina | Classificationa | 5 sec Log Kill | 10 sec Log Kill | 20 sec Log Kill |
|---|---|---|---|---|---|---|
| 0.0 | Spray― 3D Fluidics | 6538 | Gram-pos. bacteria | 0.68 | N/A | 0.80 |
| 0.0 | Spray― Needle Jet | 6538 | Gram-pos. bacteria | 0.50 | N/A | 0.42 |
| 0.8 | Spray― 3D Fluidics | 6538 | Gram-pos. bacteria | 2.17 | 2.27 | 2.91 |
| 0.8 | Spray― Needle Jet | 6538 | Gram-pos. bacteria | 1.27 | 1.85 | 2.11 |
device. 3D fluidics demonstrated superior ability to produce a greater log reduction in microbe growth when compared to laminar flow. The superior aspects of this device are excellent coverage and pressure when compared against needle jets and laminar flow. The tests show the efficacy of the product against a range of pathogenic microbes on a variety of surfaces, including surfaces similar to human skin (pigskin).
The results of testing on glass carries are shown in Part A, presented as log reductions for each exposure duration.
The results in Part B show that both the spray action and ozone concentration contribute to the antimicrobial effect. Spray flow (0.9 ppm) resulted in 2.99 log reduction in 30 sec, compared to 1.33 log reduction with laminar flow. With tap water (no ozone), spray flow resulted in 2.0 log reduction after 60 sec, compared to 0.95 log reduction with laminar flow. With respect to ozone concentration, tap water resulted in 2.0 log reduction after 60 sec, compared to 2.86 and 3.78 log reduction with 0.7 and 0.9 ppm ozonated water, respectively.
The results in Part C show that ozonated water combined with the 3D spray nozzle resulted in a 2.27 log reduction after 10 sec and 2.91 log reduction after 20 sec, in contrast to needle jet spray, which resulted in 1.85 log reduction after 10 sec and 2.11 log reduction after 20 sec.
Human factors engineering (HFE) [
The device described herein combines spraying action and the action of ozone to achieve a three-log reduction in microbes in test systems. Efficacy is achieved by a combination of fluidic action of the spray and of the ozonated water. The ozone within the water stream exerts its antimicrobial effect, and then rapidly degrades into oxygen. It is convenient and non-irritating, suitable for medical settings where personnel have heavy workloads and require multiple hand washings throughout the course of their workday. Improved hand-hygiene compliance should translate into reduced hospital-acquired infections [
Members of the Delta Faucet Co. Medical Advisory Group (Robert Lubitz, Sanjib Chouduri, John Leslie, Brian Leon, Jay Ramasamy, Amy Beth Kresse, Kalib Alexander, Garry Marty, John Noble, Patrick Jonte)―for contributions to the development of the device. NEMA Research Inc. received funding from the Delta Faucet Co. to write this manuscript. The content is solely that of the authors.
The authors declare no conflicts of interest regarding the publication of this paper.
Raffa, R.B., Pergolizzi, J.V., Taylor, R., Choudhuri, S. and Rodenbeck, R. (2018) Persistence of Healthcare-Associated (Nosocomial) Infections Due to Inadequate Hand Hygiene: Part 3―Application of Human Factors Engineering to an Ozone Hand Sanitizer. Pharmacology & Pharmacy, 9, 324-330. https://doi.org/10.4236/pp.2018.98025