Opinion – Esper Kallás: We are passengers of the world, carriers of microorganisms

Sometimes patients come to the office worried, to find that laboratory tests have shown the presence of foreign germs in their body.

How surprised would you be if you knew that we are a scaffold that hosts a multitude of viruses, bacteria, fungi and parasites? What if we say that these reach an estimated 90 trillion microorganisms?

The knowledge of the microscopic world that surrounds and inhabits us has undergone great leaps of knowledge. When Anton van Leeuwenhoek discovered the microscope in the 17th century, he did not expect to find so many organisms, even in a single drop of water. A new avenue of knowledge was open, bringing changes in biology and medicine. This allowed Robert Koch and Louis Pasteur, among others, to establish the relationship between germs and disease.

A few years ago, a new window of discovery was expanded. The emergence of techniques for detecting fragments of the genome of germs has created a new kind of “microscope”. With them, it is possible to verify the presence of genomic sequences of a much larger number of microorganisms, something that the traditional methods used in microbiology could not.

It is possible to infer that we have at least 250 times more microorganisms than cells in our body, interacting in complex systems, which we call microbiome.

But what does it mean? Mapping the distribution of germs, mainly bacteria, in organs and systems shows that there are patterns. That is, there is an interdependence between humans and their flora, involving cellular and enzymatic mechanisms. Without our microbiome, we would not survive.

Our health depends on the balance of this microbiome with us.

We are taking the initial steps in discovering this impressive ecosystem.

We know that some diseases are related to the imbalance in this interaction (dysbiosis), but we still don’t know how to manipulate the flora to treat certain human diseases. We do not yet know what suitable combinations of bacteria, viruses and fungi should be considered the standard of normality, if there is one.

Caution is therefore needed in the use of commercial microbiome tests, as there are still not enough tools to interpret them. Some have suggested the use of expensive tests, in addition to replacement of flora bacteria, with the use of so-called probiotics, in addition to dietary regimens, without any proof of beneficial effect. The use of probiotics is not yet recognized as the treatment of choice for any human condition or disease.

The current products containing probiotics are very variable, still lacking standardization in their production. Although, in general, they may seem harmless, there are still doubts about the safety of their indiscriminate consumption. There are special situations to consider. We do not know for sure how the immune system can react when dealing with people with fragile health or with immunodeficiencies, the elderly or very young children, for example.

There is also a plethora of poorly conducted studies, with biases that only seek to suggest benefits. More rigorous and robust studies are awaited to have a better understanding of how to use probiotics.

We know that, for the most part, our germ flora is good for us. We are getting to know it better and discovering how it is distributed and interacts in organs and systems.

When you come across your bacteriological exams again, remember that we are hosts to a large number of other beings, who travel with us in this world.