Summary:
Older adults in residential aged care facilities are at high risk of antimicrobial resistance due to frequent infections, high antibiotic use, and widespread medication use. Non-antibiotic medicines such as statins, diuretics, non-steroidal anti-inflammatory drugs, and proton pump inhibitors are also commonly prescribed in this group alongside antibiotics; however, their effect on antimicrobial resistance is not well understood. To explore this, nine common non-antibiotic medicines were tested with an antibiotic on two types of Escherichia coli bacteria. Ibuprofen and acetaminophen (paracetamol) were found to make the bacteria change more often, which allowed them to become strongly resistant to the antibiotic. Further testing showed that these changes affected how the bacteria copied their genetic material and how they eliminated drugs from inside their cells, both of which made it easier for them to survive. When two non-antibiotic drugs were given together, the bacteria became even more resistant. Antimicrobial resistance is a serious global health problem, causing millions of deaths worldwide each year. Although the main cause is the misuse of antibiotics, this study shows that other medicines may also contribute. These results suggest that non-antibiotic drugs should be considered when assessing antibiotic resistance risk, especially in aged care, where people often take many medicines at once.
Abstract:
Antimicrobial resistance (AMR) poses a global threat to public health. While antibiotic overuse is a primary driver, emerging evidence suggests that non-antibiotic medications (NAMs) may also contribute. This concern is particularly relevant in residential aged care facilities (RACFs), where both NAMs and antibiotics are frequently used. We investigated whether nine commonly used NAMs in RACFs, including ibuprofen, diclofenac, acetaminophen, furosemide, metformin, atorvastatin, tramadol, temazepam, and pseudoephedrine at gut-relevant concentrations, enhance ciprofloxacin-induced mutagenesis in Escherichia coli. Our findings showed that ibuprofen and acetaminophen significantly increased mutation frequency and conferred high-level ciprofloxacin resistance. Whole-genome sequencing identified mutations in GyrA, MarR, and AcrR, with the latter two correlated with overexpression of AcrAB-TolC drug efflux pump. Co-exposure to two NAMs further elevated mutation rates and ciprofloxacin resistance levels. This study underscored the overlooked role of NAMs in driving AMR and highlighted the need to reassess polypharmacy risks in aged care settings.
Article Publication Date: 25/08/2025
DOI: 10.1038/s44259-025-00144-w
