Antibiotics leave permanent traces in the intestinal microbiome
Our intestinal flora, today more commonly known as intestinal microbial microbes, contains billions of microorganisms that live in balanced coexistence and have important tasks in digestion and maintaining health. What happens when this balance is destroyed and how the intestinal flora is subsequently rebuilt, was recently investigated by an international research team in a study.
Broad-spectrum antibiotics are mostly used when other antibiotics fail. The antibacterial club not only kills pathogens, but also destroys a large part of the intestinal microbiome as a result of such medication. Researchers from the Max Delbrück Center for Molecular Medicine (MDC) and international colleagues have investigated how the intestinal flora gradually recovers after such a blow. The results were recently published in the journal “Nature Microbiology”.
Each intestine contains its own microcosm
The MDC researchers estimate that there are as many bacteria in every human intestine as there are people on earth. In most cases, the tiny creatures are beneficial to the owner’s well-being. For example, they support the digestion of food, produce vitamins, train the immune system and protect against pathogenic species.
A fragile structure
Diseases or medication can disrupt or even destroy this susceptible structure. “If it becomes unbalanced, infectious diseases, overweight and diabetes as well as chronic inflammatory bowel diseases or neurological diseases threaten it,” reports head of research Dr. Sofia Forslund in a press release. Her team was now investigating the complicated interactions between humans and microbiomes.
Antibiotics permanently alter the intestinal flora
Together with researchers from Denmark, Germany and China, Forslund and his team investigated the serious effect of broad-spectrum antibiotics on the fragile interaction of intestinal bacteria. According to the study team, it takes up to six months for the intestinal flora to recover. However, the group of researchers was unable to detect a complete regeneration of the intestinal flora. “Some sensitive bacterial species disappeared permanently,” said Forslund.
About the course of the study
During the investigations, twelve healthy men agreed to take a cocktail of the three antibiotics meropenem, gentamicin and vancomycin for four days. Her intestinal microbiome was then analysed for six months. Not only the presence of the individual bacterial species was recorded, but also their genes were determined by DNA sequencing.
Even after the administration of antibiotics, the intestine was not sterile.
The first surprise came shortly after the medication. The researchers reported that some bacteria had even survived the highly effective antibiotics. Among the survivors, the scientific team found some previously unknown species that had not yet been characterised in more detail. Other bacterial species turned into spores. In this life form, the bacteria can remain under bad conditions for a long time.
How the intestine slowly recovers
In the further course of the regeneration phase the second surprise showed up. The first bacteria, which repopulate the intestine, were mainly pathogenic strains such as Enterococcus faecalis and Fusobacterium nucleatum. “This observation explains why most antibiotics cause gastrointestinal disturbances,” concludes Forslund.
Lactic acid bacteria cause the turning point
Over time, the pathogenic strains are increasingly displaced by useful bacterial species such as the lactic acid-producing bifidobacteria, the researchers report. After six months, the intestinal flora was intact again – but not quite the same as before. Some bacterial species were missing and did not return. “The number of resistance genes in the bacteria had also increased as expected,” explains Forslund.
More caution when dealing with antibiotics
“Due to the apparently permanent loss of individual species and the increased number of resistance genes, the study shows once again how important it is to administer antibiotics with caution,” the expert sums up. It is now necessary to find out how it is better to protect the sensitive intestinal flora from antibiotics. Further information to the structure and to the intestine reorganization finds you in the articles to intestine flora to develop: So gehtts” and “Die 10 besten Tipps zur Darmsanierung”. (vb)