(Symposium on Bacterial Spores : Paper IV). Germination and the Problem of Dormancy

2013

PLoS ONE

BackgroundGermination is the irreversible loss of spore-specific properties prior to outgrowth. Because germinating spores become more susceptible to killing by stressors, induction of germination has been proposed as a spore control strategy. However, this strategy is limited by superdormant spores that remain unaffected by germinants. Harsh chemicals and heat activation are effective for stimulating germination of superdormant spores but are impractical for use in a hospital setting, where Clostridium difficile spores present a challenge. Here, we tested whether osmotic activation solutes will provide a mild alternative for stimulation of superdormant C. difficile spores in the presence of germinants as previously demonstrated in several species of Bacillus. In addition, we tested the hypothesis that the limitations of superdormancy can be circumvented with a combined approach using nisin, a FDA-approved safe bacteriocin, to inhibit outgrowth of germinated spores and osmotic activation solutes to enhance outgrowth inhibition by stimulating superdormant spores.Principal FindingsExposure to germination solution triggered ∼1 log10 colony forming units (CFU) of spores to germinate, and heat activation increased the spores that germinated to >2.5 log10CFU. Germinating spores, in contrast to dormant spores, became susceptible to inhibition by nisin. The presence of osmotic activation solutes did not stimulate germination of superdormant C. difficile spores exposed to germination solution. But, in the absence of germination solution, osmotic activation solutes enhanced nisin inhibition of superdormant spores to >3.5 log10CFU. The synergistic effects of osmotic activation solutes and nisin were associated with loss of membrane integrity.ConclusionsThese findings suggest that the synergistic effects of osmotic activation and nisin bypass the limitations of germination as a spore control strategy, and might be a novel method to safely and effectively reduce the burden of C.difficile spores on skin and environmental surfaces.

Section: Introductionmentioning

confidence: 99%

Activate to Eradicate: Inhibition of Clostridium difficile Spore Outgrowth by the Synergistic Effects of Osmotic Activation and Nisin

2013

PLoS ONE

“…Spore germination is defined as the irreversible loss of spore-specific properties and is an essential step required prior to outgrowth of vegetative cells [8], [9]. Because germinated spores become more susceptible to killing by heat and other stressors, induction of germination could be a potential strategy to facilitate eradication of C. difficile spores.…”

Section: Introductionmentioning

confidence: 99%

Triggering Germination Represents a Novel Strategy to Enhance Killing of Clostridium difficile Spores

2010

PLoS ONE

Background Clostridium difficile is an anaerobic, spore-forming bacterium that is the most common cause of healthcare-associated diarrhea in developed countries. Control of C. difficile is challenging because the spores are resistant to killing by alcohol-based hand hygiene products, antimicrobial soaps, and most disinfectants. Although initiation of germination has been shown to increase susceptibility of spores of other bacterial species to radiation and heat, it was not known if triggering of germination could be a useful strategy to increase susceptibility of C. difficile spores to radiation or other stressors.Principal FindingsHere, we demonstrated that exposure of dormant C. difficile spores to a germination solution containing amino acids, minerals, and taurocholic acid resulted in initiation of germination in room air. Germination of spores in room air resulted in significantly enhanced killing by ultraviolet-C (UV-C) radiation and heat. On surfaces in hospital rooms, application of germination solution resulted in enhanced eradication of spores by UV-C administered by an automated room decontamination device. Initiation of germination under anaerobic, but not aerobic, conditions resulted in increased susceptibility to killing by ethanol, suggesting that exposure to oxygen might prevent spores from progressing fully to outgrowth. Stimulation of germination also resulted in reduced survival of spores on surfaces in room air, possibly due to increased susceptibility to stressors such as oxygen and desiccation.ConclusionsTaken together, these data demonstrate that stimulation of germination could represent a novel method to enhance killing of spores by UV-C, and suggest the possible application of this strategy as a means to enhance killing by other agents.

“…Clostridium difficile spores remain dormant until they are exposed to agents that trigger them to come back to life through the process of germination [8]. Spore germination is defined as the irreversible loss of spore-specific properties and is an essential step required before outgrowth of vegetative cells [9].…”

mentioning

confidence: 99%

A Quaternary Ammonium Disinfectant Containing Germinants Reduces Clostridium difficile Spores on Surfaces by Inducing Susceptibility to Environmental Stressors

Open Forum Infectious Diseases

2016