Abstract
Pathogenic spore-forming bacteria pose high risks to healthcare settings, as well as in the food and beverage industries. We reported recently that novel alcohol-based formulations containing plant-derived compounds, including epigallocatechin-3-gallate-palmitate (EGCG-P), a green tea polyphenol ester, provide > 99.99% inactivation of bacterial spores within 60 sec. Based on recently published data from our group and others, we hypothesize that a combination of EGCG-P and alcohol formulated with other plant-derived ingredients would achieve high sporicidal efficacy against a wide spectrum of bacterial spores and can provide novel hand hygiene methods against bacterial spores without toxicity. The objectives of the current study were to optimize two novel formulations with combinations of glycerol, citric acid, and EGCG-P to increase sporicidal activity and explore the rapid inactivation mechanisms and suitability for sporicidal products with broad-spectrum activities against aerobic and anaerobic bacterial spores. Methods included suspension testing of two formulations against spores from Bacillus cereus and Clostridium sporogenes, quantification of spore germination, and scanning electron microscopy. The results demonstrated that these novel formulations were able to reduce spore germination by >99.999% after 30 sec exposure in suspension tests, and rapidly caused physical damage to the spores. Additional studies are warranted to determine the suitability of the novel formulations for future hand hygiene use.
Highlights
The current guidelines from United States Center for Disease Control and Prevention (CDC) and World Health Organization (WHO) for a hand hygiene method to prevent bacterial spore infection are still limited to hand wash with soap and water [1] [2]
In the US, the Environmental Protection Agency (EPA) is the regulatory body for sporicidal disinfectant tests and claims using a protocol with SOP Number: MB-15-03, based on Association of Analytical Communities (AOAC) method 966.04, to test B. subtilis, or American Society for Testing and Materials (ASTM) method E2197-11 to test B. subtilis and C. sporogenes on a hard surface
One sample t-test comparison showed that neutralized cF1 and cF2 failed to inactivate the spores, with only 0.12 ± 0.32 and 0.17 ± 0.35 log reduction respectively (p < 0.001). These results demonstrate that cF1 and cF2 rapidly inactivated B. cereus spores in the suspension tests, and the efficacy of the alcohol-based formulations were significantly improved by combination of plant-derived compounds, with both cF1 and cF2 capable of reducing the germination of B. cereus spores by >5 log10 (>99.999%)
Summary
The current guidelines from United States Center for Disease Control and Prevention (CDC) and World Health Organization (WHO) for a hand hygiene method to prevent bacterial spore infection (and norovirus infection) are still limited to hand wash with soap and water [1] [2]. This is based on evidence that the available hand hygiene products do not have sporicidal or virucidal activity (>4 log reduction of infectivity within 60 sec in a standard suspension test, or >2 log reduction of infectivity within 5 min in a human hand test: WHO guidelines attached) [1]. Criteria for a sporicidal hand hygiene product might be expected to be a >4 log reduction in 30 - 60 sec against relevant bacterial spore species
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