Impact of Interfering Substances on the Bactericidal Efficacy of Different Commercially Available Hypochlorous Acid-Based Wound Irrigation Solutions Commonly Found in South-East Asia

Abstract

The high prevalence of chronic wounds is a growing concern. Recently, hypochlorous acid (HOCl)-based solutions were introduced as an alternative antimicrobial for wound cleansing. In this study, we assessed the in vitro bactericidal activities of seven commercially available wound irrigation products commonly found in South-East Asia. The evaluation was conducted using quantitative suspension method, EN 13727 in either low or high protein conditions. Under low protein conditions, four out of the five HOCl products achieved bactericidal activity (≥5 log₁₀ reduction factor; RF) within 2-5 min, and only one product achieved 5 log₁₀ RF at 15 s. None of the HOCl achieved 5 log₁₀ RF under high protein, even after 30 min of exposure time. In contrast, protein interference on the antimicrobial activities of polyhexamethylene biguanide-based product is less pronounced (low protein: 60 s vs. high protein: 2 min to attain ≥5 log₁₀ RF). Octenidine dihydrochloride is the only active not affected by protein interference achieving ≥5 log₁₀ RF within 15 s in both low and high protein conditions. These findings warrant the need to screen antimicrobial wound care products, especially HOCl-based products, in high protein condition to better reflect the antimicrobial activities in wound care.

Keywords: antimicrobial; antimicrobial activity; commercial hypochlorous acid-based solutions; protein interference; quantitative suspension method; wound cleansing.

Figure 1

Bactericidal efficacy of various wound irrigation solutions against S. aureus according to EN 13727 in low protein condition. Log reduction achieved by the eight test solutions against S. aureus was evaluated under low protein condition, ranging from 15 s to 30 min of contact time. The dotted line represents the minimum requirement (logarithmic reduction factor of 5) to demonstrate bactericidal activity according to EN 13727. The bars represent mean values with standard deviations of two independent tests.

Figure 2

Bactericidal efficacy of various wound irrigation solutions against S. aureus according to EN 13727 in high protein condition. Log reduction achieved by the eight test solutions against S. aureus was evaluated under high protein condition, ranging from 15 s to 30 min of contact time. The dotted line represents the minimum requirement (logarithmic reduction factor of 5) to demonstrate bactericidal activity according to EN 13727. The bars represent mean values with standard deviations of two independent tests.