A team from the Institut Pasteur and their international colleagues have recently validated a new method that uses the genome of Shigella bacteria to improve identification and typing.
Infectious diarrhea represents a major public health problem at global level. Two forms of infectious diarrhea, shigellosis and bacillary dysentery, caused by bacteria of the Shigella group, are responsible for 200,000 deaths each year worldwide, especially in children. A study published in Nature Communications proposes a new standardized identification method that is more precise than previous methods.
Shigella infections are highly contagious. They frequently occur in tropical regions but are also observed in France. Each year, more than 1,000 cases are confirmed by the National Reference Center for E. coli, Shigella and Salmonella at the Institut Pasteur. Shigellosis is a disease caused by fecal contamination that may be contracted both while abroad and also in France in the event of an outbreak (at school, among family members, within the male homosexual community, etc.). The bacteria in the Shigella group are becoming resistant to all antibiotics.
Sequencing the genome to improve typing of strains
Surveillance of Shigella infections is therefore crucial and depends on the work of reference laboratories, which confirm the identification of Shigella bacteria before subdividing them into more than 50 different serotypes. Until now, laboratories were still using techniques developed more than 70 years ago, such as serotyping using sera produced in rabbits. Research conducted in the Enteric Bacterial Pathogens Unit led by Professor François-Xavier Weill at the Institut Pasteur, which houses the National Reference Center for E. coli, Shigella and Salmonella (in French), has paved the way for a modernization of the surveillance process. Shigella can now be identified and typed by sequencing the bacterial genome. This new standardized technique was validated on more than 4,000 reference strains and clinical isolates of Shigella. Unlike previous methods, the new approach, based on variations in the totality of the bacterial DNA, results in accurate classification and uniquely high-resolution typing. Comparisons between bacterial strains are no longer distorted by frequent gene transfer between different Shigella strains, as was previously the case with the traditional method. This genome-based method is now used at the National Reference Center for surveillance of Shigella infections in France.
This research was made possible by funding from the Le Roch-Les Mousquetaires Foundation.
Population structure analysis and laboratory monitoring of Shigella by core-genome multilocus sequence typing, Nature Communications, January 27, 2022
Iman Yassine1,2, Sophie Lefèvre1, Elisabeth E. Hansen1,6, Corinne Ruckly1, Isabelle Carle1, Monique Lejay-Collin1, Laëtitia Fabre1, Rayane Rafei2, Dominique Clermont3, Maria Pardos de la Gandara1, Fouad Dabboussi2, Nicholas R. Thomson4,5 & François-Xavier Weill1
1 - Institut Pasteur, Université de Paris, Unité des bactéries pathogènes entériques, Centre National de Référence des Escherichia coli, Shigella et Salmonella, Paris F-75015, France.
2 - Laboratoire Microbiologie Santé et Environnement (LMSE), Doctoral School of Sciences and Technology, Faculty of Public Health, Lebanese University, Tripoli, Lebanon.
3 - Institut Pasteur, Université de Paris, Collection de l’Institut Pasteur, F-75015 Paris, France.
4 - Wellcome Sanger Institute, Cambridge CB10 1SA, UK.
5 - London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK. 6Present address: Harvard Medical School, Boston, MA 02115, USA.