By Karen Weintraub
Might antibiotics be causing harm at a cellular level? That’s one possible conclusion from a new study by researchers at Boston University.
We’ve long known about the dangers of antibiotic resistance – that one day, the drugs will stop working – and scientists have learned in recent years that antibiotics also kill off “good” bacteria with the “bad.” But now, James J. Collins, a B.U. biomedical engineer, says his research in mice suggests that certain antibiotics, taken long-term, could be damaging our own cells.
In a study published today in Science Translational Medicine, Collins’ team showed that widely used antibiotics like ciprofloxacin and ampicillin can damage the cells’ fuel supply and cause oxidative stress, which has been linked to cancer, heart disease, Alzheimer’s and other ailments.
The research is still early and far from conclusive, but Collins says he thinks it’s convincing enough to at least merit more study.
When he and his colleagues exposed cells in a dish and then mice to these antibiotics over several weeks, they saw signs of serious cellular damage. The doses were similar to those given patients taking long-term therapy. The damage may explain why antibiotics have long been associated with side effects such as tendon, kidney and liver problems, says Collins, also a founding faculty member of the Wyss Institute for Biologically Inspired Engineering at Harvard.
His team saw the effect only in one type of antibiotics, which works by killing bacteria - so-called bacteriocidal antibiotics, like ampicillin and cipro. There is another type of antibiotic – bacteriostatic, like tetracyclines – that work differently and don’t cause problems. The researchers also found that they could fix the cellular damage by simultaneously feeding the mice an antioxidant called N-Acetylserotonin or NAC, which didn’t seem to interfere with the antibiotic’s effectiveness.
All this implies that even if certain antibiotics are damaging, the trouble can be reversed, or different antibiotics prescribed, Collins says.
It’s also possible that a small amount of cellular damage could be helpful. In a commentary that accompanied the B.U. study, researchers from Northwestern University said the positive effect of oxidative stress could be what makes livestock grow bigger and faster when fed antibiotics.
Collins says he has not yet taken that possibility into account in his research.
Bacteriocidal antibiotics tend to be used more in hospital settings, where people are quite ill, says Dr. Stuart B. Levy, Director of the Center for Adaptation Genetics & Drug Resistance at Tufts University School of Medicine. “If you don’t have your immune system working, one tends to want to go for a bacteriocidal antibiotic because the body is not prepared to handle something less than that,” says Levy, also president of the Alliance for the Prudent Use of Antibiotics, and author of “The Antibiotic Paradox: How the Misuse of Antibiotics Destroys Their Curative Powers.”
Levy says Collins’ findings are new to him and to the field.
Of course, he says, more research is needed before anyone should do anything about these potential concerns. The team’s results have to be repeated and, eventually shown – or debunked – in people.
Collins says he hopes his work will raise awareness. “I wouldn’t raise alarm just yet. Awareness is most appropriate.”
Karen Weintraub, a Cambridge-based Health and Science writer, is a frequent contributor to CommonHealth.