Effectiveness of an electrochemically activated saline solution for disinfection of hospital equipment.

To the Editor—Hospital equipment that touches patients (eg, blood pressure cuffs, bedside commodes) frequently becomes contaminated with pathogens such as Clostridium difficile, methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant enterococci (VRE).' Because equipment is often shared among patients, there is a need for simple and effective disinfection methods that include activity against C. difficile spores. ElectrochemicaUy activated saline solutions are broad-spectrum disinfectants with sporicidal activity that are generated by passing saline solution through an electrolytic cell, resulting in production of hypochlorous acid and free radicals.~ They are commonly used for disinfection of dental equipment and endoscopes, washing fruits and vegetables, and swimming pool sanitation. One formulation (ie, Vashe, PuriCore) is approved for wound care, suggesting that these solutions may have a low propensity for skin and mucous membrane irritation. Here, we tested the hypothesis that spraying equipment with electrochemicaUy activated saline containing 0.05% hypochlorous acid (Sterilox HG, PuriCore) would reduce bacterial contamination, including C. difficile spores, on equipment. The study protocol was approved by the Cleveland Veterans Affairs Medical Center's Institutional Review Board. The in vitro efficacy of Sterilox HG was compared with a 1:10 dilution of household bleach (ie, ~5,000 ppm free chlorine) for killing spores of 3 strains each of C. difficile (a restriction endonuclease analysis type BI isolate and American Type Culture CoUection strains 43593 and 43601), VRE (C68, a VanBtype isolate, and C37 and C25, VanA-type isolates), and MRSA (pulsed-field gel electrophoresis types USA300 and USA800 and ATCC strain 43300). C. difficile spores were prepared as previously described. Ten-microliter aliquots containing ~6 log10 colony-forming units (CFUs) of the organisms suspended in deionized water with or without simulated organic load containing bovine serum albumin, tryptone, and mucin (0.5 : 5 :0.4% w/v) were spread to cover 1-cm-diameter polystyrene ceU culture wells (nest ceU culture plate, Denville Scientific). After the suspensions air dried, 300 IxL of deionized water, Sterilox HG, or 10% household bleach (Clorox) was added. After 10 minutes of contact time, 1 mL of Dey-Engley neutralizer (Remel) was added, and viable organisms were quantified by plating on media selective for each pathogen. Although the complete experiments included only a 10-minute contact time, preliminary experiments with the 3 C. difficile strains did demonstrate equivalent kiUing of spores at 5 and 10 minutes for both bleach and Sterilox HG, respectively. The experiments were repeated 3 times. On hospital wards, we evaluated Sterilox HG for disinfection of wall-mounted equipment in patient rooms (ie, blood pressure cuffs, thermometer handles, and pulse oximetry finger probes), portable vital signs equipment units, intravenous medication pumps, and bedside commodes. Cultures were coUected from half of the surface area of each set of objects, using sterile swabs (BD BBL CultureSwab, Becton Dickinson) followed by sterile gauze, both premoistened with Dey-Engley neutralizer (Remel). The equipment was sprayed with Sterilox HG in sufficient quantities to thoroughly wet the surfaces (~6 sprays at one time). The surfaces were allowed to air dry (~15—30 minutes for complete drying), and the other half of the surface area was cultured. Cultures for C. difficile were processed as previously described. The swabs were also plated onto 5% sheep blood tryptic soy agar plates (Becton Dickinson) to quantify total aerobic and facultative bacteria. A Fisher exact test was used to compare the percentages of positive cultures, and paired t tests were used to compare mean CFUs recovered before versus after application of Sterilox HG.