Sporicidal activity of two disinfectants against Clostridium difficile spores
The sporicidal activity of an odour-free peracetic acid-based disinfectant (Wofasteril) and a widely-used dichloroisocyanurate preparation (Chlor-clean) was assessed against spores of the hyper-virulent strain of Clostridium difficile (ribotype 027), in the presence and absence of organic matter. In environmentally clean conditions, dichloroisocyanurate achieved a >3 log10 reduction in 3 minutes, but a minimum contact time of 9 minutes was required to reduce the viable spore load to below detection levels. Peracetic acid achieved a >3 log10 reduction in 30 minutes and was overall significantly less effective (P<0.05). However, in the presence of organic matter - which reflects the true clinical environment - there was no significant difference between the sporicidal activity of dichloroisocyanurate and peracetic acid over a 60-minute period (P=0.188). Given the greater occupational health hazards generally associated with chlorine-releasing agents, odour-free peracetic acid-based disinfectants may offer a suitable alternative for environmental disinfection.
Available from: Ian R Poxton
- "Though vegetative cells survive under aerobic conditions for only 15 min on dry surfaces, they can survive for up to 6 h on moist surfaces (Weber et al., 2010). The spores of C. difficile, however, can persist on hospital floors for up to 5 months (Kim et al., 1981) and are resistant to several cleaning agents, especially in the presence of organic matter (Fawley et al., 2007; Wheeldon et al., 2008). Surfaces contaminated with C. difficile spores can facilitate cross-colonization (Fawley & Wilcox, 2001). "
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ABSTRACT: Clostridium difficile is a common nosocomial pathogen transmitted mainly via its spores. These spores can remain viable on contaminated surfaces for several months and are resistant to most commonly used cleaning agents. Thus, effective decontamination of the environment is essential in preventing the transmission of C. difficile in health-care establishments. However, this emphasis on decontamination must also be extended to laboratories due to risk of exposure of staff to potentially virulent strains. Though few cases of laboratory-acquired infection have been reported, the threat of infection by C. difficile in the laboratory is real. Our aim was to test the efficacy of four disinfectants, Actichlor, MicroSol 3+, TriGene Advance and Virkon, and one laboratory decontaminant, Decon 90, against vegetative cells and spores of C. difficile. Five strains were selected for the study: the three most commonly encountered epidemic strains in Scotland, PCR ribotypes 106, 001 and 027, and control strains 630 and VPI 10463. MICs were determined by agar dilution and broth microdilution. All the agents tested inhibited the growth of vegetative cells of the selected strains at concentrations below the recommended working concentrations. Additionally, their effect on spores was determined by exposing the spores of these strains to different concentrations of the agents for different periods of time. For some of the agents, an exposure of 10 min was required for sporicidal activity. Further, only Actichlor was able to bring about a 3 log(10) reduction in spore numbers under clean and dirty conditions. It was also the only agent that decontaminated different hard, non-porous surfaces artificially contaminated with C. difficile spores. However, this too required an exposure time of more than 2 min and up to 10 min. In conclusion, only the chlorine-releasing agent Actichlor was found to be suitable for the elimination of C. difficile spores from the environment, making it the agent of choice for the decontamination of laboratory surfaces.
Available from: Tony Worthington
- "Contamination of the clinical environment with spores of C. difficile is a key factor associated with the spread of CDI. Furthermore, patients with CDI excrete in excess 100 C. difficile spores and cells per gram of faeces (Wilcox 2003) and sporicidal agents, including bleach and peracetic acid, are required to eliminate these spores from the environment (Wheeldon et al. 2008b). Clostridium difficile infection occurs in susceptible patients following ingestion of spores from the environment, after which, the irreversible process of spore germination occurs in the small intestine giving rise to the metabolically active vegetative forms of C. difficile which produce the exotoxins associated with disease in the large intestine (Poutanen and Simor 2004; Moir 2006). "
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ABSTRACT: To investigate the influence of chemical and physical factors on the rate and extent of germination of Clostridium difficile spores.
Germination of C. difficile spores following exposure to chemical and physical germinants was measured by loss of either heat or ethanol resistance. Sodium taurocholate and chenodeoxycholate initiated germination together with thioglycollate medium at concentrations of 0.1-100 mmol l(-1) and 10-100 mmol l(-1) respectively. Glycine (0.2% w/v) was a co-factor required for germination with sodium taurocholate. There was no significant difference in the rate of germination of C. difficile spores in aerobic and anaerobic conditions (P > 0.05) however, the initial rate of germination was significantly increased at 37 degrees C compared to 20 degrees C (P < 0.05). The optimum pH range for germination was 6.5-7.5, with a decreased rate and extent of germination occurring at pH 5.5 and 8.5.
This study demonstrates that sodium taurocholate and chenodeoxycholate initiate germination of C. difficile spores and is concentration dependant. Temperature and pH influence the rate and extent of germination.
This manuscript enhances the knowledge of the factors influencing the germination of C. difficile spores. This may be applied to the development of potential novel strategies for the prevention of C. difficile infection.
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ABSTRACT: Persistent contamination of surfaces by spores of Clostridium difficile is a major factor influencing the spread of C. difficile-associated diarrhoea (CDAD) in the clinical setting. In recent years, the antimicrobial efficacy of metal surfaces has been investigated against microorganisms including methicillin-resistant Staphylococcus aureus. This study compared the survival of C. difficile on stainless steel, a metal contact surface widely used in hospitals, and copper surfaces.
Antimicrobial efficacy was assessed using a carrier test method against dormant spores, germinating spores and vegetative cells of C. difficile (NCTC 11204 and ribotype 027) over a 3 h period in the presence and absence of organic matter.
Copper metal eliminated all vegetative cells of C. difficile within 30 min, compared with stainless steel which demonstrated no antimicrobial activity (P < 0.05). Copper significantly reduced the viability of spores of C. difficile exposed to the germinant (sodium taurocholate) in aerobic conditions within 60 min (P < 0.05) while achieving a >or=2.5 log reduction (99.8% reduction) at 3 h. Organic material did not reduce the antimicrobial efficacy of the copper surface (P > 0.05).
The use of copper surfaces within the clinical environment and application of a germination solution in infection control procedures may offer a novel way forward in eliminating C. difficile from contaminated surfaces and reducing CDAD.
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