Public Release: 

Antibiotic resistance risk from triclosan questioned

American Society for Microbiology

NEW ORLEANS - May 24, 2004 -- New research suggests that the risk of bacteria developing antibiotic resistance after exposure to the biocide triclosan may not be as great as previously believed. Researchers from the University of Manchester present their findings today at the 104th General Meeting of the American Society for Microbiology.

Studies released in the 1990s suggested that the general use of antibacterial products, particularly those using the biocide triclosan as the active ingredient, might contribute towards the development and spread of antibiotic resistance. In the laboratory, repeated sublethal exposure of the bacterium Escherichia coli to triclosan led to the emergence of triclosan-resistance in the organism, which researchers believed might select for antibiotic resistance.

In the research released today, Andrew McBain and his colleagues have discovered that the ability of E. coli to develop resistance is not shared by the vast majority of naturally occurring bacteria. Thirty distinct bacterial isolates were taken directly from kitchen sink drains or the mouths or skin of a number of volunteers. These isolates were then exposed to triclosan. Only two, the E. coli and to a lesser degree Klebsiella bacteria, developed resistance.

"These results suggest that the fears expressed about the use of triclosan were premature," says McBain. "Indeed a number of field studies conducted of homes and clinics were unable to link antibacterial use patterns with changes in resistance."


This release is a summary of a presentation from the 104th General Meeting of the American Society for Microbiology, May 23-27, 2004, in New Orleans, Louisiana. Additional information on these and other presentations at the 104th ASM General Meeting can be found online at or by contacting Jim Sliwa ( in the ASM Office of Communications. The phone number for the General Meeting Press Room is 504-670-4240 and will be active from 12:00 noon CDT, May 23 until 12:00 noon CDT, May 27.

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