Standardization News

Disinfectant Efficacy

ASTM International Committee E35 on Pesticides, Antimicrobials and Alternative Control Agents has approved its fourth standard on biofilms. E2799, Test Method for Testing Disinfectant Efficacy Against Pseudomonas aeruginosa Biofilm Using the MBEC Assay, is under the jurisdiction of Subcommittee E35.15 on Antimicrobial Agents.

Darla Goeres, Ph.D., assistant research professor, Center for Biofilm Engineering, Montana State University, explains that biofilms are cooperative communities of bacteria attached to surfaces and embedded in a slime matrix. Because biofilms are found in diverse environments, from chronic wounds and infected medical devices to oil pipelines and hot tubs, a collection of standards is needed that gives researchers test methods that allow them to grow the most relevant biofilm for their research needs.

Goeres, an E35 member, says E2799 describes how to grow biofilm in a 96-well microtiter device (MBEC Assay™), then test the efficacy of disinfectants against the established biofilm. The design of the MBEC Assay™, which was developed by Innovotech Inc., allows for testing multiple concentrations of one disinfectant, or multiple disinfectants in a single experiment, which makes it an efficient tool for researchers interested in efficacy testing.

"One of the defining characteristics of biofilm is that it is more tolerant to disinfection," says Goeres. "In practical terms, this means that it will take a high concentration, or longer contact times, to get to the same level of kill against biofilm as compared to individual bacteria in suspension. If the goal is to know how effective a particular disinfectant is against biofilm, then it is critical that the efficacy testing is done using biofilm."

Goeres believes that the MBEC Assay™ will have applications beyond determining the efficacy of disinfectants against biofilms. One future application could be screening for disinfectants effective against a wide range of bacteria responsible for food poisonings in food processing facilities.

"The MBEC Assay™ has also been used as a platform for additional assays including biofilm antibiotic susceptibility tests in both the human and animal health care industry," says Goeres. "Food chain contamination and growing bacterial resistance to antibiotics are two significant problems that mankind is facing. This technology, with its focus on biofilms, offers a new perspective to these ongoing issues." To view images of biofilm grown in the MBEC Assay™, visit the Innovotech website.

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CONTACT Technical Information: Darla M. Goeres, Ph.D., Center for Biofilm Engineering, Montana State University • Bozeman, Mont. • Phone: 406-994-2440 • Amin Omar, PhD., Innovotech Inc. • Edmonton, Alberta, Canada • Phone: 780-448-0585 O ASTM Staff: Jennifer Rodgers • Phone: 610-832-9694 O Upcoming Meeting: April 16-19, 2012 • April Committee Week • Phoenix, Ariz.

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