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In a press release dated March 15, the Institut Pasteur expressed its concern about shigellosis. The bacterium that causes this diarrheal disease would now have a new antibiotic-resistant strain in Europe, as a study has shown.
Antibiotic resistance will be the next global health threat. Today we have a new example. Researchers have found that the shigella sonei, a bacterium that causes shigellosis (or bacillary dysentery), a diarrheal disease that is particularly contagious by the faecal-oral route, would today have a strain in Europe that is highly resistant to antibiotics. The disease, which causes diarrhea for 3 to 4 days, disappears spontaneously in most cases. Nevertheless, it happens that the infection causes a more important reaction, going until severe cases, being able to involve complications or even bloody diarrhoea. Treating it with antibiotics therefore remains the only option… as long as the antibiotics work.
More than 22% of shingella strains collected in 2021 highly resistant to antibiotics
The study mentioned by the Pasteur Institute was based on the analysis of more than 7,000 strains of S. sonei and epidemiological information collected on French territory as part of the national surveillance of shigellosis by the national reference center for Escherichia coli, Shigella and Salmonella (CNR-ESS) over 17 years, between 2005 and 2021. During this period, strains said to be highly resistant to antibiotics (or XDR, for extensively drug-resistant) were identified for the first time in 2015. Then, the scientists noted that the proportion of these XDR strains, resistant to almost all the recommended antibiotics for the treatment of shigellosis, increased significantly until reaching a peak in 2021: 22.3% of all strains of S. sonei were highly resistant that year (corresponding to 99 cases).
These XDR strains have been observed in France in different contexts: in travelers returning from South Asia or Southeast Asia, during an epidemic in a school in 2017 (more than 90 cases having led to the school closure; the original case was from a trip to Southeast Asia), or in men who have sex with men (MSM). The latter were contaminated by an epidemic clone which has been spreading in Europe since 2020 but also found in North America and Australia. This subgroup of XDR strains circulating among MSM was the majority: it represented 97% of XDR strains in France in 2021.
Too systematic use of the antibiotics in question
Contacted by Doctissimo, Professor François-Xavier Weill, head of the CNR-ESS at the Institut Pasteur, explains to us what the challenges of this discovery are.
“The fact is that we knew the multi-resistance of certain strains of Sighella, but this time it is a highly resistant strain, that is to say that this strain becomes resistant to “all” the treatments of first intention.”
But why and how this strain S. sonei has it become highly resistant? The professor evokes a multifactorial antibiotic selection pressure:
“We were able to trace the history of this South Asian clone back to us. In South Asia, we know that there is a high human density, that this infectious disease circulates well and that we can buy antibiotics locally without a prescription. In France too, the male homosexual community in which this strain mainly circulates is also under antibiotic selection pressure, to treat sexually transmitted infections (STI) classics. So this bacterium was able to cumulatively acquire resistance to different antibiotics with different mechanisms depending on the place and the community in which it was circulating. There is not just one story, there are several!”
Will this disease be more difficult to treat in the future?
For Professor Weill, this infection will be more difficult to manage, without a shadow of a doubt.
“Already, for somewhat severe infections, the best option today is intravenous treatment, given in the hospital, which is one of those normally given to treat sepsis. This will further complicate care.”
Should we be worried and fear an epidemic? The expert wants to be rational. “This strain has existed for a long time, but now that we have identified the problem, we must try to break the chains of transmission, particularly in male homosexual communities, through information, prevention… We must consider this like other more classic sexually transmitted diseases, and bet on protection”.