Report of the 30th congress of the european Helicobacter and microbiota study group

The key contribution of culturomics

The first presentation of the postgraduate course was provided by D. Raoult from Marseille, France, who revisited the concept of gut microbiota using culturomics. Studies using 16S rDNA sequencing and metagenomics have opened the field, but these techniques have limitations due to discrepancies that may arise at the level of DNA extraction, sequencing, and bioinformatic analysis, moreover, these techniques are missing minority partners. However, the emergence of the concept of culturomics has enabled the discovery of an important number of new bacterial species, Archae, as well as large viruses, which could not be detected by metagenomic analyses. This approach employed by D. Raoult was initially extremely cumbersome (using 200 different media), but is now more straightforward, using only 17 media, and new bugs continue to be discovered every week.

Gut microbiota and antibiotics

The second talk was also fascinating. M. Blaser (New York, NY, USA) presented the suspected link between gut microbiota disturbances and several chronic diseases for which the aetiology is still doubtful, such as asthma, obesity, diabetes, inflammatory bowel disease, etc. The prevalence of these diseases is increasing worldwide and parallels the increased use of antibiotics. There are now data showing that bacteria that have co-evolved with humans are crucial to their good health. There is an age window when the microbiota is established (0-3 years), and consumption of antibiotics at this age may lead to the disappearance of part of the microbiota and therefore the bacterial diversity which is an important criterium for health. Experiments in mice have shown that antibiotics can modify the composition of gut microbiota leading to increased adiposity and modification of the immune response, favouring several diseases.

With the description of the association between gut dysbiosis and several diseases at present, an interesting approach to consider is how to limit the impact of antibiotics on gut microbiota. A first step is to add probiotics to antibiotic treatments, however, all probiotics are not equal. Saccharomyces boulardii appears to be the leader in this area. All studies have shown a beneficial effect of this yeast on antibiotic-related diarrhoea. Among Lactobacilli, there is one emerging species in this respect; Lactobacillus rhamnosus GG, as revealed by H. Sokol.

Non-probiotic approaches

There are currently non-probiotic approaches to prevent gut dysbiosis which were presented by A. Andremont (Paris, France). Indeed, antibiotics are absorbed in the small intestine and their negative effects on gut microbiota occur essentially in the colon. Thus, first attempts were made to deliver β-lactamase to the colon to avoid the effect of β-lactam antibiotics, and subsequently other alternatives using specifically coated absorbent-like activated charcoal. Experiments in mice and dogs have been successful, especially for fluoroquinolone antibiotics.

Once dysbiosis is established, restoration is possible by faecal microbiota transplantation (FMT). It is possible to successfully treat Clostridium difficile infection using allogenic FMT. Autologous transplantation could be an option in the case of planned antibiotic treatment and would be more acceptable given that the risk of unknown pathogens would be avoided. For FMT, there is a need for common legislation in Europe as well as standardization of the process.