Antibacterial Products May Worsen Problem of Resistant Bacteria

St. Jude Researchers Say

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St. Jude Children's Research Hospital

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In a paper published in the April 16 Journal of Biological Chemistry, Charles O. Rock, Ph.D., and Richard J. Heath, Ph.D., researchers in the biochemistry department at St. Jude Children's Research Hospital, find that the use of antibacterial products may actually make drug-resistant strains of bacteria more prevalent.

Here's the problem: the use of popular antibacterial products such as soaps and body washes introduces an antibacterial compound called triclosan into the environment. Triclosan interacts with bacteria -- and, as is their nature, the bacteria develop resistance to the compound. The accumulation of triclosan in the environment could lead to the emergence of drug-resistant bacteria, Rock said. As a result, the very antibacterial products designed to kill the bacteria would become ineffective.

"We consider this to be a serious public health concern," Rock said.

These findings are important because it has been widely reported that triclosan acts as a non-specific agent that attacks bacterial membranes and kills indiscriminately -- much like a bomb. If triclosan works in this way, then it is unlikely that bacteria could devise a way to develop resistance. On the contrary, the St. Jude study shows that triclosan interferes with a specific biochemical process inside bacteria. Thus, bacteria can and do find a way to develop resistance.

Rock reported in a paper published in September that it was possible for E. coli bacteria to develop a resistance to triclosan. Rock showed that triclosan inhibited an enzyme in fatty acid biosynthesis produced by a gene called fabI, and that mutations in the fabI gene caused resistance to triclosan. In this latest paper, the St. Jude team explains how this resistance occurs. The researchers pinpointed that the formation of a specific complex (FabI-NAD+-triclosan) accounts for the effectiveness of triclosan as an antibacterial agent. If the formation of this complex is prevented, bacteria can become resistant to triclosan. Rock's group has identified a specific mutation in the fabI gene that prevents the formation of this complex and thus, creates resistance to triclosan.

"The ability of E. coli to acquire genetic resistance to triclosan and related compounds through mutations in the fabI gene suggests that the widespread use of this drug will lead to the appearance of resistant organisms that will eventually compromise the usefulness of triclosan, and other antibacterials that interact with the same target," Rock said.

Rock also points out that there is little or no evidence that the inclusion of triclosan in most antibacterial products offers any additional protection against bacteria. He believes that the Food and Drug Administration should regulate the distribution of triclosan just as it regulates other antibacterial drugs.

St. Jude Children's Research Hospital, in Memphis, Tennessee, was founded by the late entertainer Danny Thomas. The hospital is an internationally recognized biomedical research center dedicated to finding cures for catastrophic diseases of childhood. The hospital's work is supported through funds raised by the American Lebanese Syrian Associated Charities (ALSAC). All St. Jude patients are treated regardless of their ability to pay. ALSAC covers all costs of treatment beyond those reimbursed by third party insurers, and total costs for families who have no insurance.

CONTACT: Deidre Malone or Bert Kelly, Public Relations Office of St. Jude Children's Research Hospital, 901-495-3306