The worldwide distribution of genetically and phylogenetically diverse B acillus cereus isolates harbouring B acillus anthracis ‐like plasmids

Summary B acillus cereus is a close relative of B . anthracis , the causative agent of anthrax whose pathogenic determinants are located on p XO 1 and p XO 2 plasmids. B acillus anthracis ‐like plasmids have been also noted among B . cereus , however, genetic features of B . cereus harbouring these elements remain largely undescribed, especially from the global perspective. Herein, we present the genetic polymorphism, population structure and phylogeny of B . cereus with p XO 1‐/p XO 2‐like plasmids originating from A rgentina, K azakhstan, K enya and P oland. The plasmids were found in about 17% of the isolates, but their frequencies and expression of replicons differed within and between populations. In the multi‐locus sequence typing, the bacteria exhibited high genetic polymorphism reflected by 116 sequencing types, including 84 singletons and 10 clonal complexes, which mainly consisted of isolates of the same origin. The phylogenetic analysis of p XO 1‐/p XO 2‐like positive B . cereus isolates revealed six independent clades; in certain clades individual populations predominated. Generally, B . cereus with p XO 1‐/p XO 2‐like plasmids did not indicate the genetic relationship with B . anthracis , and cannot be classified into an evolutionary independent anthrax line within the B . cereus group. Our report is of a crucial importance for discovering the genetic specificity and evolution of B . cereus bacilli.