Triclosan Causes Rapid Restructuring of Gut Microbiome

Triclosan, a common antimicrobial and antifungal agent found in many consumer products, can rapidly disrupt the bacterial communities found in the digestive system, according to a new study.

Researchers at Oregon State University (OSU, Corvallis, USA) exposed 45 adult zebrafish to triclosan-laden food for four or seven days or a control diet, and analyzed their microbial communities using 16S rRNA amplicon sequencing. They found that Triclosan was associated with rapid shifts in microbiome structure and diversity. They also found that operational taxonomic units (OTUs) associated with the Enterobacteriaceae were susceptible to triclosan exposure, while OTUs associated with Pseudomonas appeared to be more resilient.


The researchers also found that triclosan was associated an overall increase in the number of negative topological interactions per microbe. Together, the data indicates that triclosan exposure results in altered composition and ecological dynamics of microbial communities in the gut. The researchers clarified that although health implications are unclear, dysfunction of the gut microbiome has been associated with diabetes, heart disease, arthritis, and malnutrition. The study was published on May 18, 2016, in PLOS One.

“Clearly there may be situations where antibacterial agents are needed. However, scientists now have evidence that intestinal bacteria may have metabolic, cardiovascular, autoimmune and neurological impacts, and concerns about overuse of these agents are valid,” said lead author Christopher Gaulke, PhD, of the OSU College of Science. “Cumulative impacts are also possible. We need to do significantly more evaluation of their effects, some of which might be dramatic and long lasting.”

“There has been a legacy of concern about exposure to microbial pathogens, which has led to increased use of these antimicrobial products. There is now a growing awareness of the importance of the bacteria in our gut microbiome for human health,” added corresponding author Thomas Sharpton, PhD. “Overuse of antibiotics can lead to the rise of ‘superbugs.’ There are consequences to constantly trying to kill the bacteria in the world around us, aspects we’re just beginning to understand.”

Triclosan is a polychloro phenoxy phenol antibacterial and antifungal agent found in numerous consumer products and in health care settings, such as in surgical scrubs and personnel hand washes. Showering or bathing with a 2% triclosan solution has become a recommended regimen in surgical units for the decolonization of patients whose skin is carrying methicillin-resistant Staphylococcus aureus (MRSA). On the negative side, triclosan has been found to decrease circulating levels of thyroxine hormone (T4), which could lead to altered behavior, learning disabilities, and/or infertility.

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