New Standard Helps Measure Antimicrobial Effectiveness Against Biofilms

The test method will show a treated material’s resistance to microbial colonization and subsequent biofilm formation relative to an untreated (control) sample. The standard is specifically designed to examine tubular samples or small quantities of yarns and fibers.

ASTM International member Matt Henry notes that antimicrobial tests typically quantify the population or concentration of microorganisms that survive exposure to a sample treated with an antimicrobial agent without distinguishing whether the surviving microorganisms were in a planktonic (free-floating) or an adhered (biofilm) state.

“A unique feature of the standard is that it not only assesses the antimicrobial activity of the test sample against free-floating bacteria, but it can also determine the ability of the sample to resist microbial colonization that can lead to biofilm formation,” says Henry, vice president of microbiology and medical devices applications at NanoHorizons, Inc.

“This distinction is important because the behavior of bacteria in a biofilm state differs substantially from when they are in a planktonic state, especially with respect to susceptibility to disinfectants, sanitizers and antimicrobial agents.  Evaluating the ability of a material’s surface to resist bacterial colonization may be of equal or greater significance than its efficacy versus planktonic bacteria.”

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