Unlocking the Sporicidal Potential of Ethanol: Induced Sporicidal Activity of Ethanol against <i>Clostridium difficile</i> and <i>Bacillus</i> Spores under Altered Physical and Chemical Conditions

<div><p>Background</p><p>Due to their efficacy and convenience, alcohol-based hand sanitizers have been widely adopted as the primary method of hand hygiene in healthcare settings. However, alcohols lack activity against bacterial spores produced by pathogens such as <i>Clostridium difficile</i> and <i>Bacillus anthracis</i>. We hypothesized that sporicidal activity could be induced in alcohols through alteration of physical or chemical conditions that have been shown to degrade or allow penetration of spore coats.</p><p>Principal Findings</p><p>Acidification, alkalinization, and heating of ethanol induced rapid sporicidal activity against <i>C</i>. <i>difficile</i>, and to a lesser extent <i>Bacillus thuringiensis</i> and <i>Bacillus subtilis</i>. The sporicidal activity of acidified ethanol was enhanced by increasing ionic strength and mild elevations in temperature. On skin, sporicidal ethanol formulations were as effective as soap and water hand washing in reducing levels of <i>C</i>. <i>difficile</i> spores.</p><p>Conclusions</p><p>These findings demonstrate that novel ethanol-based sporicidal hand hygiene formulations can be developed through alteration of physical and chemical conditions.</p>