It seems like everyone knows that antibiotic resistance is the next big thing, and researchers from around the globe are looking to find its causes. Now, it’s time to add antidepressants to the list. This latest research is from the same group in Queensland that showed the link between triclosan use and antibiotic resistance. Led by Dr. Guo of the Advanced Water Management Centre (AWMC) at the University of Queensland, the researchers looked into fluoxetine, which is marketed commercially as Prozac. The study was published in the most recent edition of Environmental International.
Briefly, the researchers exposed the bacterium, Escherichia coli to varying concentrations of fluoxetine, and continuously cultured for 30 days. After this period, randomly selected bacteria were grown in liquid culture media and the minimum inhibitory concentration was determined against a screen of different antibiotics. Changes in genetic expression were confirmed by RNA sequencing and proteomic analysis. They found that there was an increase in the genes and proteins that code for proteins that can pump antibiotics out of the cell. Presumably, these pumps are also responsible for the export of the fluoxetine.
Beyond the sensationalist headlines, there is one main caveat that need to be understood. Firstly, and most importantly, this was a laboratory study under perfect conditions. The concentration of fluoxetine used were quite high (5-50 mg/L), whereas no significant effect was seen at the 0.5 mg/L concentration. In the body, and more importantly, in water systems, Prozac/fluoxetine is potentially detected at the nanogram per litre level, which is 3 magnitudes (1000 fold!) lower than in this study. Also, this was studied in E. coli which is ideal for laboratory studies, but is hardly one of our main concerns for antibiotic resistant microorganisms.
The article does highlight one important thing. The presence of components in the water systems can be mutagenic, and while it is unlikely that they will definitely lead to antibiotic resistance, it is still a small possibility. That being said, it is NOT RECOMMENDED to stop taking antidepressants or any other medications, as these links are still quite weak. The research being done is interesting, but the media fails to report the important details to generate more clicks.
Citation:
Jin, M., Lu, J., Chen, Z., Nguyen, S. H., Mao, L., Li, J., … & Guo, J. (2018). Antidepressant fluoxetine induces multiple antibiotics resistance in Escherichia coli via ROS-mediated mutagenesis. Environment international, 120, 421-430.
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