GoKawiilInspiration 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 bacteria1. But it’s not just carbamazepine. In 2018, microbiologist Lisa Maier, now at the University of Tübingen in Germany, and her colleagues assessed the effects of nearly 1,200 drugs on 40 types of intestinal bacterium2. They found that 24% of the drugs had antibacterial activity.
The team also found that the bacteria that resisted non-antibiotic drugs most strongly were also the most resistant to antibiotics. “That basically implies that if you develop a resistance to a non-antibiotic drug, that will result in a cross-resistance to an antibiotic,” Maier says.
Antibiotic resistance is a growing issue, and efforts are being made to control the threat by addressing the drugs’ overuse. However, the possibility that non-antibiotic medications might be helping to drive the process is a concern. “Bacteria don’t care if we call a drug an antibiotic or not; they only care whether it has an antibacterial activity,” says Ronen Ben-Ami, an infectious-disease physician at Tel Aviv Sourasky Medical Centre in Israel. And although this antibacterial activity might be much less potent than that of recognized antibiotics, people take many of the implicated drugs for years — much longer than a ten-day course of antibiotics.
Evidence from animal and human studies is now needed to determine whether these drugs are involved. “We have lots of in vitro findings,” says Amir Mitchell, a systems biologist at the University of Massachusetts Chan Medical School in Worcester. “Whether they hold in vivo is a key question.”
Selection pressure
Antibiotic resistance starts small. When bacteria are exposed to an antibiotic, they might survive if they have a protective genetic variant. With time and repeated exposure, these bacteria can grow into a stable population that is resistant to the treatment.
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