Antimicrobial agent may not kill all germs
Triclosan doesn't always do the trick, study shows
Nicolle Charboneau, Healthscout, July 25, 2000
THURSDAY, July 13 (HealthSCOUT) -- Think that antiseptic-fortified cutting board is killing germs while you prepare dinner? Think again.
New research in today's issue of Nature suggests that triclosan, an antimicrobial agent added to cutting boards, certain plastics and even toothpaste and deodorants, may not be effective against certain bacteria, including Streptococcus pneumoniae. The research suggests triclosan may act more like a drug than an antimicrobial, which means it could face federal regulation.
Triclosan, which is manufactured by Ciba-Geigy -- a division of Basel, Switzerland-based Novartis -- works by interfering with the activity of a crucial enzyme called FabI. But as it turns out, several nasty strains of bacteria don't have that particular enzyme, so they resist triclosan. These bacteria include S. pneumoniae, which can cause pneumonia or infect the cerebrospinal fluid and cause meningitis.
Study author Charles Rock, a member in biochemistry at St. Jude's Children's Research Hospital in Memphis, Tenn., found that S. pneumoniae and several other disease-causing bacteria use an enzyme called FabK.
"Those bacteria were completely resistant to the effects of triclosan," says Rock. "The importance of that experiment is that it proves in that case that triclosan has no non-specific mechanism in that particular bacteria."
Why is that important? Triclosan is supposed to kill all bacteria, without the possibility that resistance could develop. Obviously, that's not the case, says Rock.
"It means that triclosan isn't an antiseptic," he says. "It's a drug."
And when you call something a drug, it means it has to be regulated. It may change how the U.S. Food and Drug Administration characterizes triclosan.
"If you're going to call triclosan a drug...then you have to prove that it's effective, which hasn't been done," says Rock. In fact, Rock believes triclosan actually contributes to the problem of bacterial resistance.
Dr. Stuart Levy, the director of the Center for Adaptation Genetics and Drug Resistance at Tufts University in Boston, feels strongly that triclosan should be categorized as a drug.
"Triclosan acts like an antibiotic. It has a target, and its potential selection to resistant strains can occur in many more organisms than previously considered," he says. "Its misuse will select for resistant strains, and in that way, it will mimic what antibiotics do."
So is it essential to own an antimicrobial cutting board? Rock says that while triclosan isn't harmful, it may not be very helpful.
"My view is that handwashing and good hygiene is sufficient," he says.
For everything that you could ever want to know about triclosan, check out the Mad Scientist Network.
SOURCES: Interviews with Charles O. Rock, Ph.D., member, department of biochemistry, St. Jude Children's Research Hospital and University of Tennessee, Memphis, Tenn.; Stuart B. Levy, M.D., professor of molecular biology and microbiology, department of microbiology, director, Center for Adaptation Genetics and Drug Resistance, Tufts University School of Medicine, Boston; July 13, 2000 Nature
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