“The massive use of antibiotics and antimicrobials in people and animals has led us to these substances appearing in unexpected environmental samples,” he says. Irantzu Vergara, researcher in the IBeA group at the University of the Basque Country. Medicines that are not completely metabolized in the body reach the environment through different routes (such as manure, sewage sludge used as fertilizers, etc.), leach into the soil and can end up passing on to crops or worms, which are the base of the food chain. “Although short-term toxicity has not been demonstrated in humans, unintentional consumption of antibiotics through the diet can cause problems for allergic people; and the effects of long-term exposure are still unknown. However, the biggest problem associated with this contamination is the spread of multi-resistant bacteria, for which it is difficult to find an effective treatment in case of infection, causing up to 33,000 deaths a year in Europe,” explains Vergara.
In order to address this problem, the IBeA research group has developed two analysis methods that allow the detection of very low concentrations of antimicrobials in vegetables and worms: “Although high drug concentrations can be expected in manure, after Transfer of these substances to vegetables or worms, much lower concentrations are expected, so sensitive methods are needed to detect them,” says Vergara.
The methods developed by Vergara in the laboratories of the University of the Basque Country allow the simultaneous determination of a wide range of antimicrobial medications, as well as various products derived from their transformation. As the researcher explains, “medicines can be excreted in their original form or transformed after being metabolized (after undergoing certain changes within our body). Furthermore, these are very sensitive compounds that, due to conditions of temperature, humidity, light, etc., degrade and transform very easily in the environment.”
The methods report an important advance, since “until now there were no analytical methods to simultaneously study a wide range of antimicrobials in vegetables and worms, and furthermore they were not focused on the analysis of transformation products. Each family of antibiotics has different physicochemical properties, and the fact that the same analysis method can be used to analyze all of them is very important. In addition, we have achieved quite low detection limits, which allow us to detect very low concentrations of these substances in the environment.”
Sampling of vegetables in different parts of the CAPV
In the case of vegetables, the research group has taken samples of vegetables from different parts of the Basque Country, both organic and non-organic farming. “Our objective was to measure the magnitude of the antibiotic problem in the Basque Country. The analytical studies carried out provide data on the existence of antimicrobial drugs and their derivatives in vegetables: we have verified that there is a transfer of both antimicrobials and degradation products from the soil to the vegetables. That is, there is a problem of contamination by antimicrobials in the Basque Country,” he adds.
In the case of worms, however, they have carried out an experiment under controlled exposure conditions; that is, “this is a study designed and carried out in the laboratory with worms. “We wanted to check if, if we have contaminated soil, the worms that feed on those soils are capable of accumulating antimicrobials in their bodies.” In the study they have observed that these antimicrobials accumulate in the body and that they generate a wide variety of transformation products not reported until now.”
Vergara highlights the need to “continue researching in a multidisciplinary manner along these lines, since this is a problem that will affect the entire society in the coming decades.” Water treatment plants currently do not have completely effective treatments to eliminate drug residues, and these waters are often used for irrigation. “As there is such a large, constant input of antimicrobials into the environment, bacteria are getting used to living with them and generating resistance,” he explains. The researcher warns that “in fact, there are already cases in which there are no effective treatments for people who become infected with multi-resistant bacteria. It is important to continue advancing in research to be able to minimize the problem or start looking for solutions in the short or medium term.”
Additional information
This study is part of the doctoral thesis that Irantzu Vergara is doing in the IBeA research group of the University of the Basque Country, under the direction of Ailette Prieto and Maitane Olivares.
