Triclosan - Resistance Concerns

Resistance Concerns

An article coauthored by Stuart Levy in the August 6, 1998 issue of Nature warned that triclosan's overuse could cause resistant strains of bacteria to develop, in much the same way that antibiotic-resistant bacterial strains are emerging. In 2003, the Scottish Sunday Herald newspaper reported that some UK supermarkets and other retailers were considering phasing out products containing triclosan.

It has since been shown that while the laboratory method used by Levy was not effective in predicting bacterial resistance for biocides like triclosan, triclosan does reduce species diversity, kills off efficient TCS degrader species (see citation's Table 4), and that it should be considered that "degradation of an ecosystem may rearrange the competitive hierarchy". At least seven peer-reviewed and published studies have been conducted demonstrating that triclosan is not significantly associated with bacterial resistance over the short term, including one study coauthored by Levy. However, the major concern over resistant strains is not that they will alter resistance profiles over the short term. The concern is that superbugs will evolve against which no bactericide can be used. For example, as noted above, triclosan is effective against MRSA. However, overuse of triclosan could lead to TMRSA (MRSA that is also triclosan-resistant).

Some level of triclosan resistance can occur in some microorganisms, but the larger concern is with the potential for cross-resistance or co-resistance to other antimicrobials. Studies investigating this possibility have been limited. The European Commission Scientific Committee on Consumer Safety (SCCS) concludes that to date, there is no evidence that using triclosan leads to an increase in antibiotic resistance. However it is too early to say that triclosan exposure never leads to microbial resistance, as there is not yet enough information to make a full risk analysis.