Few microbiological differences in households using antibacterials

A microbiological survey of households finds little significant difference in levels of bacteria or antibiotic resistance between those that use antibacterial cleaning products and those who do not. Researchers from Tufts University School of Medicine report their findings today at the 103rd General Meeting of the American Society for Microbiology.

“The use of biocides, also called antibacterials, has become increasingly popular for regular household use. While originally developed to control transmission of infectious disease agents among sick patients, these same products are increasingly incorporated into domestic household cleaners, healthcare products, clothes, and plastics,” says Bonnie Marshall, one of the study researchers.

In contrast to alcohols, peroxides and bleach, which quickly dissipate from environmental surfaces, common antibacterial chemicals such as triclosan and quaternary ammonium compounds leave residues which can exert a more prolonged effect on the microbiology of the application site. Given that triclosan-resistant mutants of E. coli and Staphylococcus aureus have been isolated in the laboratory, concern has developed over the effect of home usage of residue-producing biocides on the microbiology of the home. Of particular interest is the possibility that prolonged application may promote higher levels of antibiotic resistance in the normal and/or disease-causing bacteria.

Marshall and her colleagues performed a “snapshot” survey of the aerobic bacteria from bathroom and kitchen surfaces of 38 households located in the greater Boston and Cincinnati areas. They evaluated the total numbers of gram-negative and gram-positive bacteria, including potential pathogens, as well as the frequency of bacterial resistance to six different antibiotics. There were large variations among identical sites in different homes, and significant numbers of bacteria could be recovered, even from sites where antibacterial products were in use. The highest numbers of bacteria were recovered from kitchen sponges and from sink and bathtub drains.

“In this one-time investigation of the microbiology of households, there was no significant difference in the numbers and kinds of bacteria found in those using or not using antibacterials,” says Marshall.

This release is a summary of a presentation from the 103rd General Meeting of the American Society for Microbiology, May 18-22, 2003, in Washington, DC. Additional information on these and other presentations at the 103rd ASM General Meeting can be found online at http://www.asm.org/Media/index.asp?bid=17053 or by contacting Jim Sliwa (jsliwa@asmusa.org) in the ASM Office of Communications. The phone number for the General Meeting Press Room is (202) 249-4064 and will be active from 12:00 noon EDT, May 18 until 12:00 noon EDT, May 22.