Efficacy of Dilute Hypochlorite Solutions and an Electrochemically Activated Saline Solution Containing Hypochlorous Acid for Disinfection of Methicillin-Resistant Staphylococcus aureus in a Pig Skin Model

Abstract

Recurrent skin and soft-tissue infections (SSTIs) due to Staphylococcus aureus are a common problem in children and adults. Many of these SSTIs are caused by a community-associated methicillin-resistant S. aureus (MRSA) strain designated USA300. Dilute bleach baths are commonly used as part of decolonization regimens for recurrent SSTI, particularly in children. However, limited data are available on the microbiological efficacy of dilute bleach on skin, and optimal concentrations are unknown. Recent practice guidelines for MRSA from the Infectious Diseases Society of America recommend a teaspoon of household bleach per gallon of bath water (1.3 μL/mL or a quarter cup per quarter tub of water) for 15 minutes twice weekly. On the basis of in vitro data, Fisher et al suggested that a higher concentration (2.5 μL/mL or a half cup per quarter tub of water) might be more effective (more than a 3-log reduction in MRSA in 5 minutes versus a 2-log reduction for a 1.2-μL/mL concentration). In contrast, more dilute bleach solutions (eg, a quarter cup of 6% sodium hypochlorite per bathtub full of water) for 5 days in combination with intranasal mupirocin were effective for eradication of colonization in a recent randomized trial, but 29% of patients in the mupirocin/bleach bath group developed recurrent colonization within 4 months. Here, we used a pig skin model to examine the effectiveness of various concentrations of dilute bleach solution and an electrochemically activated saline solution containing 0.025% hypochlorous acid (Vashe; PuriCore) for disinfection of MRSA on skin. Vashe is safe for use on skin and is commercially available as a wound care product.