Everyday non-antibiotic meds like ibuprofen and paracetamol can make E. coli more likely to mutate and resist antibiotics.
The study looked at how nine widely used medications interact with the antibiotic ciprofloxacin, raising mutation rates and multi-drug resistance.
Genetic sleuthing revealed that these drugs trigger defenses in bacteria — like mutation triggers and efflux pumps — that help them survive antibiotics.
You’d think popping an over-the-counter painkiller like ibuprofen or acetaminophen is harmless.
However, a new study suggests they might have a hidden side hustle: helping bacteria become antibiotic-resistant.
That’s especially worrying for places like aged-care homes, where people often take several medicines every day. Recent research from the University of South Australia zeroes in on how these familiar drugs may be silently empowering one of our most common bacterial foes — Escherichia coli — to shrug off powerful antibiotics.
“Antibiotics have long been vital in treating infectious diseases, but their widespread overuse and misuse have driven a global rise in antibiotic-resistant bacteria,” researcher Rietie Venter said in a news release.
“This is especially prevalent in residential aged care facilities, where older people are more likely to be prescribed multiple medications – not just antibiotics, but also drugs for pain, sleep, or blood pressure – making it an ideal breeding ground for gut bacteria to become resistant to antibiotics.
The study
Researchers tested nine widely used non-antibiotic medications (NAMs) — including ibuprofen, acetaminophen (paracetamol), diclofenac, furosemide, metformin, atorvastatin, tramadol, temazepam, and pseudoephedrine — at concentrations modeled to reflect what ends up in the gut.
They exposed two strains of E. coli (one lab strain and one from a retirement community resident) to ciprofloxacin, a common antibiotic, both with and without the NAMs. Then they measured how often mutations happened, tracked bacterial growth, and did whole-genome sequencing to hunt for genetic changes.
The results
The results weren’t trivial. When paired with ciprofloxacin, ibuprofen and acetaminophen significantly boosted mutation rates and allowed E. coli to develop strong resistance — not just to ciprofloxacin, but to other antibiotics too.
Digging into the genetics revealed mutations in key bacterial genes — like GyrA, MarR, and AcrR — which led to overexpression of the AcrAB-TolC efflux pump. In plain terms, these changes help bacteria actively eject antibiotics and survive.
Combining two NAMs made things worse: mutation rates and resistance levels climbed even more. It’s a clear hint that mixing medications — polypharmacy — might inadvertently supercharge antibiotic resistance.
“Antibiotic resistance isn’t just about antibiotics anymore,” Venter said.“This study is a clear reminder that we need to carefully consider the risks of using multiple medications – particularly in aged care where residents are often prescribed a mix of long-term treatments.
“This doesn’t mean we should stop using these medications, but we do need to be more mindful about how they interact with antibiotics – and that includes looking beyond just two-drug combinations.”