Shigella
spp., emerging from multiple origins of
Escherichia coli
, poses a significant health threat as a causative agent of bacillary dysentery. While multiple serotypes of four different species have evolved via independent lineages,
Shigella
spp. are designated as a single pathotype, primarily because of their common mode of pathogenesis. Convergent horizontal transfer events have so far been attributed to the commonalities in the evolution of virulence across diverse lineages. However, the role of mutational convergence in such parallel evolution is not yet well understood. Here we have carried out a genome-wide analysis of
Shigella
strains from all four species to detect the core genes (i.e. the ones present in all analyzed strains) acquiring convergent mutations of evolutionarily recent origin. Simulation studies show non-neutral accumulation of these convergent mutations across species, suggesting their adaptive role in the evolution of
Shigella
virulence.
S. dysenteriae
strain 197, representing highly virulent type 1 (
Sd
1) clone, carries excessively high number of core genes with recent convergent mutations compared to other analyzed strains. We propose that this high frequency of adaptive convergence in
S. dysenteriae
strain 197 could be linked to recent re-emergence of the
Sd
1 clone and its increased resistance to antimicrobials.
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