Genomic analysis of pathogenic isolates of Vibrio cholerae from eastern Democratic Republic of the Congo (2014-2017)

摘要

Cholera is a severe diarrheal disease caused by the Gram-negative bacterium Vibrio cholerae. After originating in Asia, the disease spread across sub-Saharan Africa, notably Democratic Republic of the Congo. The aim of our study was to assess the transmission pattern of V. cholerae strains prevailing in eastern DRC, and determine their genetic relatedness to strains from other African countries and other parts of the world. Between 2014 and 2017, we isolated V. cholerae from fecal samples of patients with acute diarrhea in eastern DRC, and subsequently examined the DNA of the bacteria. The results show that they all clustered in two genetic groups (ST69 and ST515) falling within the third transmission wave of the current seventh pandemic El Tor (7PET) lineage and T10 introduction event in East Africa. The genetic signature of ST515 may be involved in its adaptation to environmental conditions found in eastern DRC, and contribute to its extended geographic distribution. Indeed, unlike the locally endemic ST69, ST515 is spreading extensively through DRC cross-border countries such as South Sudan, Tanzania, Uganda and Zambia. This plainly justifies a regional strategy to strengthen the fight against cholera in eastern Africa.