Inspiration takes many forms. For Jianhua Guo, it was his friend’s daughter’s diarrhoea. Guo — an environmental microbiologist at the University of Queensland in Brisbane, Australia — was studying the emergence of antibiotic-resistant bacteria in hospital waste water. His research indicated that the resistance arises in response to not just antibiotics, but also other compounds that happen to have antibacterial properties. His friend’s daughter had epilepsy and had been prescribed the anticonvulsant drug carbamazepine. Guo thought that the girl’s gastric issues might be due to the drug not only affecting her neurons, as intended, but also killing her intestinal bacteria. If so, he surmised, bacteria might evolve resistance to carbamazepine — and, more worryingly, perhaps also to antibiotics. Nature Outlook: Antimicrobial resistance In 2019, Guo’s group showed that carbamazepine could induce resistance to several commonly used antibiotics in cultured bacteria 1 . But it’s not just carbamazepine.…