Antidepressant Medications and Antibiotic Resistance

Antidepressants are one of the most commonly prescribed medications worldwide.¹ Some common antidepressant medications include escitalopram (Lexapro), duloxetine (Cymbalta), sertraline (Zoloft), and bupropion (Wellbutrin).² According to research from the University of Queensland in Australia, one of the side effects of antidepressants is an increased chance of antibiotic resistance.^1,3

Antibiotic resistance is dangerous

Antibiotic resistance has become increasingly common in recent years.¹ Antibiotic prescriptions fight bacterial infections, but their overprescribing has helped lead to these medications losing their effectiveness. 

Bacteria can replicate and often mutate as a defence mechanism for their survival. These mutations mean the bacteria get more competent at defending molecules designed to kill them or better at disguising themselves in the body. The replication can mean proliferation beyond the initial site of infection. If the harmful bacteria can deflect or hide within the body, infections can spread and possibly become lethal.

Antidepressants bring out bacterial defences

Current research shows antidepressants trigger bacteria to enter “protection mode” by the following defence mechanisms.^1,3 

Ramped-up mutation

Analysis for mutations conferring antibiotic resistance included independent testing for responses. Eight antibiotics were added to cultures with the antidepressant fluoxetine and anaerobic  E. coli bacteria. The eight antibiotics tested were as follows:

1. chloramphenicol,
2. amoxicillin,
3. fluoroquinolone, 
4. aminoglycoside, 
5. β-lactams, 
6. tetracycline
7. kanamycin,
8. and cephalexin.³ 

When the mutant bacteria were tested in an aerobic environment with fluoxetine, researchers identified ramped-up mutations and high defences against the following antibiotics:

1. fluoroquinolone,
2. aminoglycoside,
3. β-lactams,
4. tetracycline,
5. and chloramphenicol.³ 

The combination of the oxygen with the cultures allowed for the creation of damaging reactive oxygen species (ROS).^1,3 The ROS help the mechanisms relating to mutagenesis (creating mutations), giving rise to the idea that ROS may in part be responsible for antibiotic resistance.

Pump antibiotics out

Bacteria have genes that code for membrane pumps (efflux pumps) that actively transport, or pump, metabolites, and chemicals out of cells. After antidepressant exposure, the concentration of out-pump gene expression was more than twice normal levels.³ This suggests that fluoxetine encourages E. coli to push out any antibiotics that may be absorbed, thus increasing resistance.

Transfer of genes between bacteria

The antidepressant sertraline is another suspect drug of antibiotic resistance. Researchers found increases in the transfer of genetic material between bacteria when sertraline was used.¹ The communication of genes between bacteria speeds up the processes of mutation and, thus antibiotic resistance.¹ 

The antidepressants and antibiotic resistance relationship

Antidepressants may increase the chances of bacteria mutations and antibiotic resistance in certain environments. Thankfully, there are ways to help empower against the risks — good hygiene practices, a healthy lifestyle, and regular check-ups. The studies took place in a controlled environment, but human life is not as controlled. More research is needed on the antidepressant and antibiotic resistance relationship. Most importantly, take your medications as prescribed, and do not stop taking your antidepressants without the approval and monitoring of your healthcare provider. 

Written by Bryn Evans and Melissa Traynor MHSc

References

1. Drew, L. How antidepressants help bacteria resist antibiotics. Nature. (Jan 24 2023). Accessed on Mar 2, 2023. Retrieved from https://www.nature.com/articles/d41586-023-00186-y
2. Common antidepressants can increase antibiotic resistance. The University of Queensland Australia. (Feb 1 2023). Accessed on Mar 3 2023. Retrieved from https://www.uq.edu.au/news/article/2023/01/common-antidepressants-can-increase-antibiotic-resistance#:~:text=University%20of%20Queensland%20researchers%20have,bacteria’s%20resistance%20to%20antibiotic%20medications
3. Jin M et al. Antidepressant fluoxetine induces multiple antibiotics resistance in Escherichia coli via ROS-mediated mutagenesis. Environment International. 2018;120:421-430.https://doi.org/10.1016/j.envint.2018.07.046
4. Maier, L., Pruteanu, M., Kuhn, M. et al. Extensive impact of non-antibiotic drugs on human gut bacteria. Nature 555, 623–628 (2018). https://doi.org/10.1038/nature25979