Is Triclosan Creating Antibiotic Resistant Superbugs?

By: Alexandra Ortiz

Figure 1. Schematic of possible mechanisms involved in Triclosan promoted transfer of antibiotic resistance. Triclosan was found to promote the uptake of resistance abilities by 1) inducing an oxidative stress response that 2) caused outer membrane damage, 3) stimulating other stress responses, 4) promote the production of transfer structures (pili), and 6) increased energy levels to sustain the synthesis of transfer structures. (From Lu et al., 2018)

Antibiotic resistance is one of the most urgent threats to public health. The emergence and spread of antibiotic resistance can be fueled by the presence of non-antibiotic antimicrobials (NAAM), such as triclosan, in our environment. Despite triclosan’s ban in 2017, it is still found in municipal wastewater and soils. Triclosan serves as a selective driving force for bacteria that are resistant. Bacteria become resistant by obtaining pieces of DNA that are grouped into transferable packages, plasmids, and code for the resistance properties from other bacteria. Lu and colleagues were able to investigate whether triclosan’s ability to stimulate the transfer of antibiotic multi-resistance genes within the same and different bacteria. They determined that triclosan at concentrations below lethal levels commonly found in our wastewater promoted the transfer of antibiotic resistance genes. Worryingly, triclosan might considerably accelerate the spread of antibiotic resistance by (Figure 1): increasing the bacteria’s stress response (1); damaging bacterial membranes so that packaged DNA can be taken up (2,3); increase the production of structures needed for transfer (4); boost bacterial energy levels required for transfer (6). Therefore, with ubiquitous human exposure to triclosan and antibiotic resistance rising, it is important to assess the impact of triclosan and other NAAM chemicals on the dissemination of antibiotic resistance.

Original Article:

Lu, J., Wang, Y., Li, J., Mao, L., Nguyen S.H., Duarte, T., Coin, L., et al., 2018. Triclosan at environmentally relevant concentrations promotes horizontal transfer of multidrug resistance genes within and across bacterial genera. Environment International.121, 1217-1226.