AUTHOR=Edwards Adrianne N. , Karim Samiha T. , Pascual Ricardo A. , Jowhar Lina M. , Anderson Sarah E. , McBride Shonna M. 

TITLE=Chemical and Stress Resistances of Clostridium difficile Spores and Vegetative Cells

JOURNAL=Frontiers in Microbiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2016.01698

DOI=10.3389/fmicb.2016.01698

ISSN=1664-302X

ABSTRACT=<p><italic>Clostridium difficile</italic> is a Gram-positive, sporogenic and anaerobic bacterium that causes a potentially fatal colitis. <italic>C. difficile</italic> enters the body as dormant spores that germinate in the colon to form vegetative cells that secrete toxins and cause the symptoms of infection. During transit through the intestine, some vegetative cells transform into spores, which are more resistant to killing by environmental insults than the vegetative cells. Understanding the inherent resistance properties of the vegetative and spore forms of <italic>C. difficile</italic> is imperative for the development of methods to target and destroy the bacterium. The objective of this study was to define the chemical and environmental resistance properties of <italic>C. difficile</italic> vegetative cells and spores. We examined vegetative cell and spore tolerances of three <italic>C. difficile</italic> strains, including 630Δ<italic>erm</italic>, a 012 ribotype and a derivative of a past epidemic strain; R20291, a 027 ribotype and current epidemic strain; and 5325, a clinical isolate that is a 078 ribotype. All isolates were tested for tolerance to ethanol, oxygen, hydrogen peroxide, butanol, chloroform, heat and sodium hypochlorite (household bleach). Our results indicate that 630Δ<italic>erm</italic> vegetative cells (630 <italic>spo0A</italic>) are more resistant to oxidative stress than those of R20291 (R20291 <italic>spo0A</italic>) and 5325 (5325 <italic>spo0A</italic>). In addition, 5325 <italic>spo0A</italic> vegetative cells exhibited greater resistance to organic solvents. In contrast, 630Δ<italic>erm</italic> spores were more sensitive than R20291 or 5325 spores to butanol. Spores from all three strains exhibited high levels of resistance to ethanol, hydrogen peroxide, chloroform and heat, although R20291 spores were more resistant to temperatures in the range of 60–75°C. Finally, household bleach served as the only chemical reagent tested that consistently reduced <italic>C. difficile</italic> vegetative cells and spores of all tested strains. These findings establish conditions that result in vegetative cell and spore elimination and illustrate the resistance of <italic>C. difficile</italic> to common decontamination methods. These results further demonstrate that the vegetative cells and spores of various <italic>C. difficile</italic> strains have different resistance properties that may impact decontamination of surfaces and hands.</p>