From drug resistance to dietary habits: spotlight on the microbiome

The human gut microbiota is one of the most densely populated microbial ecosystems. The variety of microorganisms present in this microbiota significantly impacts various aspects of our health and well-being, including the ability to resist the effects of medications, levels of bodily inflammation, and even dietary habits. Therefore, the balance of beneficial and harmful bacteria in our intestines is crucial to maintaining many different aspects of health. Medications, along with diet and genetics, are among the primary factors influencing the composition of the microbiota. All of these factors will be discussed at the tenth edition of The Barcelona Debates on the Human Microbiome, a globally renowned scientific gathering on microbiome organized by IrsiCaixa –a centre jointly supported by the "la Caixa" Foundation and the Department of Health of the Generalitat de Catalunya– to be held on June 27^th and 28^th at the CosmoCaixa Science Museum in Barcelona.

The congress, held within the framework of the European project MISTRAL led by IrsiCaixa, is coordinated by IrsiCaixa's director, Bonaventura Clotet, the emeritus physician of the Digestive System Research Unit at the Vall d’Hebron Research Institute, Francisco Guarner, and the principal investigator of IrsiCaixa and head of the Infectious Diseases Service at the Germans Trias i Pujol Hospital, Roger Paredes. "Understanding the human microbiome is crucial to addressing global health challenges, especially antimicrobial resistance, which threatens our society. Through this scientific event in Barcelona, we are consolidating our leadership position in this research area", emphasizes Guarner.

The triad of intestinal health: medications, genes, and diet

Several studies to be presented at The Barcelona Debates on the Human Microbiome reveal how certain commonly used medications, as well as diet and specific genes, can alter the composition and metabolism of the microbiome. In the case of medications, these changes can lead to the development of antimicrobial resistance mechanisms.

"Antibiotics, laxatives, acid production inhibitors in the stomach, and glucose level regulators are among the drugs that most alter the intestinal ecosystem", explains Arnau Vich Vila, speaker at the scientific event and postdoctoral researcher at KU Leuven. This alteration can result in imbalanced growth of certain microorganisms and the emergence of resistances and pathologies. "Acid production inhibitors, commonly known as gastric protectors, for example, disrupt the balance of intestinal pH. This change in acidity favors the development of microorganisms typical of the oral cavity, while inhibiting the growth of beneficial intestinal bacteria", explains Vich-Vila.

Meanwhile, Sara Vieira-Silva, associate researcher at the University of Mainz and speaker at the scientific session, also reflects on the interactions between drugs and the microbiota, especially in inflammatory processes. While studying mild inflammation caused by obesity, Vieira-Silva and her team discovered that statins, medications used to control cholesterol, can rebalance the intestinal microbiota. "Individuals with a high body mass index are at greater risk of imbalance in the intestinal microbiota, with significantly lower levels of key beneficial bacteria such as Faecalibacterium and generally low microbial density", explains Vieira-Silva. "These indicators are associated with higher systemic inflammation, and statins have been shown to improve this imbalance", she adds.

Additionally, genes and diet have proven to be determining factors in human gut health. A balanced diet rich in legumes, fish, and nuts helps maintain beneficial bacteria, reducing the occurrence of opportunistic bacteria and intestinal inflammation. Vich-Vila, who will also address the influence of genetics and diet at The Barcelona Debates on the Human Microbiome, poses the question: "Can genetics influence our microbiome and thereby determine our dietary habits? The answer is affirmative. In fact, we have observed genetic components that impact the presence of certain bacteria associated with sugar consumption, dairy, or the development of food intolerances".

A silent pandemic

Microorganisms can develop resistance to drugs due to mutations in their genome or the acquisition of resistant genes from external sources. "The microbiome is an ecosystem where this acquisition of external genes can occur more easily, as it is a confined space with a high density of microorganisms capable of transferring genes among themselves", explains Paredes. Thus, this gene transfer can turn the microbiome into a critical point for the spread of antimicrobial resistance. It is essential to promote effective public health policies to address this issue and mitigate the increasing threat of drug resistance.