Jianhua Guo is a professor at the Australian Centre for Water and Environmental Biotechnology. His research focuses on removing contaminants from wastewater and the environmental dimensions of antimicrobial resistance. One of those dimensions is the overuse of antibiotics, which promotes resistance to these drugs.

Guo wondered if the same might hold true for other types of pharmaceuticals as well. His lab found that they definitely do. Specific antidepressants—SSRIs and SNRIs—promote resistance to different classes of antibiotics. This resistance is heritable over 33 bacterial generations, even once the antidepressant is removed.

So much work

Antidepressants are among the most prescribed and ingested drugs there are. They account for roughly 5 percent of the pharmaceutical market share—about the same as antibiotics—and four of the top 10 most prescribed psychiatric meds in the US.