A potato extract may offer us insight into a new strategy for antibiotic research: Don't kill the bacteria, just prevent them from attaching to our cells. Researchers from the Miami University of Ohio report the results of their study on this potato extract at the 100th General Meeting of the American Society for Microbiology.
"In the past several years many scientists have come to believe that there is another way to prevent or cure infections, besides simply killing the causitive organisms," says researcher Dr. Marjorie Cowan. "Nearly all microorganisms must secure themselves firmly to their target tissue in order to cause disease. Preventing or disrupting the attachment of microorganisms to host tissue could provide a kinder, gentler approach to curing or preventing disease."
All current antibiotics work by essentially killing bacteria. In the search for new antibiotics, one strategy used has been to screen plant extracts, long used by traditional healers, for their killing ability. The researchers in this study chose a different strategy. They decided to study a plant extract that was known to have anti-infective properties but had previously been discounted as an antibiotic because it did not kill the bacteria. They chose the potato.
"We found that a water extract of the outer few millimeters of a potato inhibited the attachment of an oral streptococcus to the substance it uses for attachment to the tooth surface. It also prevented the attachment of E. coli which cause urinary tract infections to its host cells," says Cowan.
The researchers have identified the specific compound within the extract responsible for inhibiting bacterial adhesion. It is called polyphenol oxidase, or PPO, and is a common enzyme in plants and is responsible for browning of a variety of fruits and vegetables including apples, potatoes and mushrooms.
Using substances like PPO to treat infections could also help solve the growing problem of antibiotic resistance, says Cowan. The destruction of bacteria sensitive to antibiotics is a primary requisite for the rise of resistant mutants. Since these compounds don't kill the sensitive bacteria, they remain around to compete and crowd out any individual resistant bacteria that may develop.
This release is a summary of a presentation from the 100th General Meeting of the American Society for Microbiology, May 21-25, 2000, in Los Angeles. Additional information on these and other presentations at the 100th ASM General Meeting can be found online at http://www.asmusa.org/pcsrc/gm2000/presskit.htm or by contacting Jim Sliwa jsliwa@asmusa.org in the ASM Office of Communications.
The phone number for the General Meeting Press Room is 213-765-4660 and will be active from 10:00 a.m., May 21 until 12:00 noon, May 25.