Antimicrobial resistance is largely driven by the overuse and misuse of antibiotics. However, the impact of other drugs in this process is often overlooked. Recently, Australian scientists conducted a study published in the journal PNAS showing that certain antidepressants, such as sertraline and duloxetine, can induce resistance in E. coli to various antibiotics. This highlights the need to consider the impact of non-antibiotic drugs on antimicrobial resistance.
Antibiotics can have multiple off-target effects on both disease-causing and non-disease-causing bacteria, as well as on host physiology. The gut contains the largest concentration of bacteria in the body and is a common target for antimicrobials. For example, broad-spectrum antibiotics can alter the gut microbiome for weeks or even months. The human body contains approximately 1 kg of bacteria, known as the intestinal microbiota. These bacteria produce all the key central neurotransmitters, such as serotonin and GABA, which can transmit signals to the brain through the enteric nervous system and the vagus nerve.
The Gut-Brain Connection and the Antibiotic-Like Role of Antidepressants
The discovery of isoniazid, the first antidepressant, which was originally developed as an antibacterial drug to treat tuberculosis, had unexpected side effects in the form of improved mood and sleep. This gave rise to the “monoamine hypothesis of depression” and the development of several classes of antidepressants. Recent studies have shown that some antidepressants, such as fluoxetine, have antibacterial effects under certain circumstances.
However, antidepressants can also alter the sensitivity of microorganisms to antimicrobials and facilitate the spread of multidrug resistance genes. The prescription and use of antidepressants should take into account their impact on the spread of antibiotic resistance and the consequences of depleting the current antibiotic arsenal. As the consumption of antidepressants increases, especially in Western countries, where they make up a significant portion of the pharmaceutical market, it is important to consider the potential impact on antimicrobial resistance. Depression is a priority of the World Health Organization’s Mental Health Gap Action Program (mhGAP).