The microbiome is defined as the set of microorganisms living on the surface and inside the body. It contains bacteria but also viruses and fungi. Today, thanks to the emergence of new advanced technologies and to find alternatives to antimicrobial resistance, scientists are starting to take an interest in the virome or mycobiome, since viruses are installed in various niches of the human body such as inside the nose and intestinal mucosa. It is in the intestinal viroma that the greatest number of viral occupants have been identified. Scientists consider the virome to be “the largest, most diverse, and most dynamic part of the microbiome,” and most of the viruses in our gut are bacteriophages. Where there are bacteria, there are bacteriophages. These infect bacteria and use their cellular machinery to replicate their genetic material.
From the 1920s to the 1950s, scientists tried to understand whether bacteriophages, capable of destroying human pathogens, could also treat bacterial infections. They then discovered that bacteriophage therapy was effective and without side effects. Then, when the antibiotics arrived, this technique went into the background. But now with the growing emergence of antimicrobial resistance on a global scale, researchers are looking for alternatives and are interested again in phage therapy.
It especially interests them by its specificity. Because while antibiotics kill a broad spectrum of bacterial species, some of which are “good,” bacteriophages target only a narrow range of strains within the same bacterial species. They attack only the desired bacteria and continue to replicate until they have eradicated the infection. Conversely, it happens that bacteriophages are beneficial for populations of bacteria.
What is the role of bacteriophages in intestinal diseases?
When a phage becomes active, it can destroy communities of bacteria, which potentially allows bad bacteria to fill the void and can lead to microbial imbalance. This can be associated with conditions such as inflammatory bowel disease, colitis, obesity, or chronic fatigue syndrome.
However, researchers are not sure whether bacteriophages are responsible, because if they cause changes in the intestine, these are not always the cause of the disease. In fact, bacteriophages could, on the contrary, be passively modified by changes in intestinal bacteria.
Until now, scientists have been unable to study the virome because viruses have no equivalent gene between species. But now, the advances made in the sequencing of the next generation allow progress. While less is known about the role of viruses in health than in disease, it seems likely that viruses also play a role in a healthy body. Although viruses are best known for causing disease, some of them have no relevance to human cells.
Global consumption of antibiotics has exploded in fifteen years
But given the concern of the international community in the face of antimicrobial resistance, the renewed interest in the bacteriophage will undoubtedly push more researchers to take an interest in the subject, and it must be recognized that faced with the complexity of the composition of microbiome, the task promises to be difficult. “The composition of the intestinal microbiome is not the same during the different stages of life, or even during the hours of the same day”, explain the scientists. And of course, each individual has their own microbiome, bacteria and bacteriophages.
Between 2000 and 2015, global antibiotic consumption increased from 21.1 billion daily doses to 34.8 billion, an increase of 65%. However, only countries with middle or low income (LMIC) have greatly increased their consumption of antibiotics (+ 114% in 16 years). For example, the use of antibiotics has increased by 50% in India, 79% in China and 65% in Pakistan. Thanks to awareness campaigns, however, it is relatively low (+ 6%) in high-income countries (HIC). In France, it has decreased slightly in recent years, especially among young people, according to a recent report by Public health France. Hexagon remains a pretty poor student, however, since it remains the third-poorest country in Europe in this area, behind Greece and Cyprus.