Success of Escherichia coli O25b:H4 Sequence Type 131 Clade C Associated with a Decrease in Virulence
Marion Duprilot, Alexandra Baron, François Blanquart, Sara Dion, Cassandra Pouget, Philippe Lettéron, Saskia-Camille Flament-Simon, Olivier Clermont, Érick Denamur, Marie-Hélène Nicolas-Chanoine
Abstract
virulence. Competition assays in sepsis, gut colonization, and urinary tract infection models between the most anciently diverged strain (B1 subclade), one C1 subclade strain, and a B4 subclade recombining strain harboring some clade C-specific genetic events showed that the B1 strain always outcompeted the C1 strain, whereas the B4 strain outcompeted the C1 strain, depending on the mouse niches. All these findings strongly suggest that clade C evolution includes a progressive loss of virulence involving multiple genes, possibly enhancing overall strain fitness by avoiding severe infections, even if it comes at the cost of a lower colonization ability.