July 3, 2017

expert reaction to study of triclosan and antibiotic resistance

Publishing in the Journal of Antimicrobial Chemotherapy scientists report that antimicrobial resistance may be exacerbated by the antibacterial agent triclosan.

Prof. Jodi Lindsay, Institute of Infection and Immunity at St George’s, University of London, said:

“In our bodies and in our household environments there are ecosystems of bacteria, all competing with each other for food and space.  If these bacterial populations are exposed to antibiotics, the ones that are already resistant survive while the rest are killed off.

“This new study shows that bacteria already resistant to a class of antibiotics called fluoroquinolones may also survive better when they are exposed to triclosan, a common agent in household products.  The study did not show that triclosan causes bacteria to become antibiotic resistant.  Therefore, every time we use an antibiotic or triclosan we increase the chances that bacteria that are already resistant will be competitive, survive and spread.  The more bacteria in our environment that are resistant, the more infections will be caused by these bacteria, and these infections will be harder to treat with current antibiotics.

“Not all household disinfectants select for bacteria that are antibiotic resistant, but it seems that triclosan does.  We should consider limiting the use of these products.”

Dr Kim Hardie, Associate Professor in Molecular Microbiology at the University of Nottingham, said:

“This study highlights how important it is to investigate how one antimicrobial might influence another and that this should inform how we use these active ingredients to save lives. The Study is well conducted, the data is reliable and fits with other studies. However, it also opens up more questions, which have not all been addressed in full. Why does one bacterium behave differently to another quite closely related one, and how relevant is this?

“The study has been performed on isolated, laboratory grown bacteria, or through the use of biochemical assays, and the relevance in more ‘real life’ situations now needs to be investigated. An interesting potential mechanistic link between the antibiotic target and the knock-on effect of the triclosan has been identified, but the molecular pathway of the link remains to be uncovered. Moreover, the relevance to other antimicrobials remains to be determined to see how far the implications of this study extend. The study highlights how more information is required to make an informed decision about changing daily practice at home and in hospitals in the UK in line with other countries that have already banned triclosan.”

Prof. Brendan Wren, Dean of Faculty of Infectious and Tropical Diseases at the London School of Hygiene & Tropical Medicine, said:

“This study nicely illustrates the collateral damage that occurs when pathogenic bacteria mutate to become resistant to antibiotics. It provides mechanistic evidence of how antibiotic resistance can also impinge on the efficacy of commonly used biocides such as Triclosan.

“These findings have wider implications meaning that antibiotic usage and the development of antibiotic resistance may also affect the usefulness of biocides found in a wide range of disinfectants. This provides further compelling evidence for the need to reduce the use of antibiotics in the food chain and by prescription.”

* ‘Quinolone-resistant gyrase mutants demonstrate decreased susceptibility to triclosan’ by Mark Webber et al published in the Journal of Antimicrobial Chemotherapy on Monday 3 July. 

Declared interests

None declared.