Here's why depression pills could be fuelling rise of superbugs

A new research now suggests that antidepressants could be contributing to the rise in superbugs. According to researchers, an ingredient in the commonly prescribed antidepressant fluoxetine – or Prozac—causes mutation in some bacteria making them resistant to antibiotics.

According to the World Health Organization, antibiotic resistance is one of the biggest threats to our health and it occurs when the genes in bacteria change in order to resist the effects of antibiotics.

If these drugs fail, common infections such as pneumonia and salmonella are difficult and at times, even impossible to treat.

Measures to combat the superbug crisis have focused on reducing over-prescription of antibiotics, because the more antibiotics are used, the greater the chance that bacteria will develop ways to survive them — and these robust bacteria go on to proliferate.

Research in the BMJ earlier this year found that a fifth of antibiotics prescribed by GPs in England are given to patients who don’t need them.

However, the new study, published in the journal Environment International, suggests other drugs could also play a part.

The research looked at whether the antidepressant fluoxetine had any effect on the E. coli bacterium, which causes food poisoning.

Fluoxetine was chosen as it passes through the body unchanged before entering the environment via urine. Up to 11 per cent of fluoxetine is thought to get into the environment — where high levels are thought to induce multi-drug resistance. In the study, E. coli was exposed to four concentrations of fluoxetine — 0.5, 5.0, 50 and 100mg/l — for 30 days in the laboratory.

Results showed that, when exposed to 5mg/l or more, the bacterium underwent genetic changes that made it resistant to antibiotics such as chloramphenicol, amoxicillin and tetracycline, often used to treat acne as well as respiratory and urinary tract infections.

The greater the fluoxetine dose E. coli was exposed to, the higher the rate of antibiotic resistance.

Researchers from the University of Queensland in Australia said that fluoxetine causes an overproduction of free radicals (unstable atoms that damage cells and DNA) in the E. coli which leads to mutations in the bacterium’s efflux pumps — these push toxins, including antibiotics, out of the cell. The altered pumps removed the antibiotics so rapidly that they had no chance to get to work.