Bacillus cereus Genome sequencing and assembly. Bacillus cereus

Members of the Bacillus cereus group are spore-forming organisms commonly associated with food poisoning and intestinal infections. Moreover, some species of the group (i.e. Bacillus cereus sensu stricto and B. thuringiensis) can cause bacteremia in humans, mainly in immunocompromised individuals. Here we performed the genetic characterization of seventeen human clinical strains belonging to B. cereus group isolated from blood culture. The whole genome sequencing (WGS) revealed that the isolates were closely related to B. cereus sensu stricto and B. thuringiensis type strain. The draft genome revealed the genetic diversity of our isolates, which were assigned to different Sequence Types. Based on panC nucleotide sequence, the isolates were grouped in the III and IV phylogenetic group. The NHE, cer and inhA gene cluster, entA, entFM, plcA and plcB were the most commonly detected virulence genes. Genes related to the resistance to penicillin, trimethoprim and ceftriaxone were identified in most of the isolates. Intriguingly, the majority of these virulence and AMR genes appeared to be evenly distributed among B. cereus s.s. isolates as well as B. thuringiensis isolates. We showed as the WGS represents a good approach to rapidly characterize B. cereus group strains, being able to give useful information about genetic epidemiology, the presence of virulence and antimicrobial genes, and finally about the hazard related to this underestimated risk.