Disinfectant Testing for Clostridium difficile

A proposed new ASTM International standard will describe the production and semipurification of Clostridium difficile spores, known as endospores, when testing environmental surface disinfectants that are used to combat C. difficile. WK31504, Test Method for Producing High Titers of Viable and Semi-Purified Spores of Clostridium difficile Using a Liquid Medium, is being developed by Subcommittee E35.15 on Antimicrobial Agents, part of ASTM International Committee E35 on Pesticides, Antimicrobials, and Alternative Control Agents. The liquid medium described in WK31504 will make it possible to properly test disinfectants for a higher confidence in their ability to deal with C. difficile in the environment, leading to safer healthcare facilities.

C. difficile has emerged as a significant healthcare-associated pathogen over the past two decades. Elderly people on antibiotic treatments can be at high risk of acquiring a potentially fatal infection because powerful antibiotics that upset the balance of gut flora in the body make it easier for C. difficile to take effect. The most prominent clinical outcome of this is severe and frequent episodes of diarrhea, which can lead to contamination of the healthcare environment, where environmentally stable and disinfectant-resistant spores can survive and spread to cause more cases of infection.

"While C. difficile is not a new pathogen, it has acquired much greater significance due to the increasing number of vulnerable individuals in our communities," says Syed Satter, Ph.D., professor emeritus, microbiology, and director, Centre for Research on Environmental Microbiology at the University of Ottawa. "Other contributing factors may be genetic changes in the pathogen contributing to greater virulence, widening antibiotic use and increasing life expectancy."

Sattar notes that up until a few years ago, several environmental surface disinfectants had label claims of activity against C. difficile. However, these claims were based on testing against the vegetative form of the organism, which is easier to kill than the spores. This discovery led to a guidance document issued by the U.S. Environmental Protection Agency requiring that any new labels claims against C. difficile be based on testing with spores.

All interested parties are invited to become involved in the standards developing activities of E35.

CONTACT Technical Information: Syed Sattar, Ph.D., Centre for Research on Environmental Microbiology (CREM), Faculty of Medicine, University of Ottawa • Ottawa, Ontario, Canada • Phone: 613-562-5800, ext. 8314 | ASTM Staff: Jennifer Rodgers • Phone: 610-832-9694 | Upcoming Meeting: Oct. 21-24 • October Committee Week • Jacksonville, Fla.

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