A study conducted by ITM found antibiotic-resistant bacteria in the oral cavities of Belgian citizens who hadn’t taken antibiotics in decades. Based on these findings, the researchers hypothesize that even very low amounts of antibiotics present in our food are sufficient to fuel resistance in certain bacteria. This would be especially troubling for species such as Klebsiella pneumoniae, which causes severe infection of the lungs and is becoming increasingly resistant to existing treatments.
Tiny larvae, big problem
In order to protect the beneficial bacteria present in our bodies, regulators such as the European Medicines Agency (EMA), the World Health Organization (WHO) and the Food and Agriculture Organization (FAO) of the United Nations have set limits on the amount of antibiotics permitted in food. However, the new study by ITM shows that even antibiotic can lead to the development of resistance in some bacterial species.
The ITM researchers used wax moth larvae as a model system for studying bacterial infections because of their human-like response to infections. Typically, scientists first test substances in wax moths, later in mice, and finally in humans. This sequence helps to bridge the gap between lab experiments and real-world applications, while limiting the amount of higher-order animals used in scientific research.
Surprisingly, the researchers discovered that even a tiny fraction, just one tenth, of the ‘safe’ amount of ciprofloxacin, a commonly used antibiotic in pig and cow farming, could promote bacterial resistance in wax moth larvae. Furthermore, the researchers found that even a single dose of the allowed daily amount of the antibiotic erythromycin in food can lead to resistance in Streptococcus pneumoniae, the bacterium causing pneumonia.
As these bacteria are among the top contenders for developing resistance to treatments, they pose a serious threat to global health.
These findings are alarming, as they suggest that low doses can make infections difficult, if not impossible, to treat. It means that what we consider safe levels of antibiotics in our food might be contributing to the rise of superbugs.
Public health implications
“Investigations are ongoing to determine if ‘acceptable’ doses of antibiotics cause similar resistance in mice and humans,” says Chris Kenyon, head of the Sexually Transmitted Infections Unit at ITM and associate professor Infectious Diseases at the University of Cape Town. “If this is the case, then imagine the effect of the worldwide consumption of these doses repeatedly over the course of lifetimes. It could contribute to the accelerating rates of resistance that we are witnessing,” stresses Kenyon.
New strategies
This research challenges current standards for antibiotic use in food production and calls for a re-evaluation to prevent the rise of untreatable bacterial strains. Alternatives include extending the period without antibiotics before animal slaughter or reducing overcrowding, which leads to higher antibiotic consumption.
“Previously, Europe banned the use of antibiotics as growth promoters in food animals. It was anticipated that this would lead to huge protests and a reduced production. However, there was little resistance, and the assessments of this change have been so positive that other regions, such as the USA, have followed suit,” explains . “We are currently testing safe antibiotic doses in mice and humans and if these show the same results then we will need to reduce the concentrations that are allowed in food.”
“…imagine the effect of the worldwide consumption of these doses repeatedly over the course of lifetimes. It could contribute to the accelerating rates of resistance that we are witnessing,”
These findings suggest that our current guidelines for antibiotic levels in food might need re-evaluation. As studies move from laboratory models to human trials, it could become clear that what we currently consider ‘safe’ could have broader implications for public health. While more research is needed, this study raises important questions about how we manage antibiotics in our food.
