The rapid increase in scientific knowledge and numerous studies have made it possible to understand the close links between the imbalance of the intestinal microbiome and numerous pathologies. Indeed, it has been shown that patients suffering from infectious diseases, cancers, metabolic diseases and certain autoimmune diseases have a significantly different microbiome from healthy individuals.
Resistance and bacterial infections
When taking antibiotics, the microbiome is profoundly disrupted and can be colonised by antibiotic-resistant or pathogenic bacteria, which are usually unable to survive and thrive in a healthy microbiome.
Antibiotic treatments promote intestinal colonization and proliferation of the C. difficile bacterium, which is directly responsible for C. difficile infections. These infections cause severe and painful diarrhea in patients and drastically reduce their quality of life. They can be fatal in some cases.
The selective pressure exerted by antibiotics is also responsible for the emergence and spread of antibiotic-resistant bacteria, which are responsible for a wide range of difficult-to-treat infections. This is of particular concern in patients who are already seriously ill, such as those with hematologic malignancies or patients in intensive care units. In these patients, disruption of the microbiome can lead to serious complications, including bacteremia (entry of bacteria into the bloodstream) which is often fatal.
Protecting the intestinal microbiome of individuals can reduce the risk of developing serious infections and spreading antibiotic-resistant bacteria in the environment.
Efficacy of cancer immunotherapies
The intestinal microbiome is essential in the formation and development of the human immune system. Several studies have shown a link between the intestinal microbiome and the development of cancer, anti-cancer immunity and the effectiveness of anti-cancer treatments. They have shown that the disturbance caused by antibiotics (known as dysbiosis) is responsible for an alteration in the immunity of patients, which leads to a loss of efficacy of cancer immunotherapies such as immune checkpoint inhibitors (ICI), which ultimately leads to a reduction in survival in these patients. More than 50 academic and industrial studies and a dozen meta-analyses published since 2018 now agree that antibiotics have a deleterious impact on survival in cancer patients treated with immune checkpoint inhibitors.
Protecting the intestinal microbiome of cancer patients treated with immunotherapies should improve their survival.
Graft versus host disease
Antibiotic-induced dysbiosis can also impair the immunity of patients with hematologic malignancies receiving allogeneic hematopoietic stem cell transplantation (allo-HSCT) and thus promote the development of graft-versus-host disease (GvHD). Acute GvHD occurs in 25-40% of these patients and is a major cause of graft failure and post-transplant mortality.
Protecting the intestinal microbiome of transplant patients should reduce the occurrence and severity of GvHD and increase the survival of these patients.