Background. Bacillus cereus group (Bc) comprises twenty-six closely related species of spore-forming environmental bacteria. Recently, increased sepsis and septic shock caused by Bc were reported in preterm neonates (PN), and the mortality rate can reach up to 30%. Using Whole Genome Sequencing (WGS) increasingly used to characterize Bc strains, The team aimed to determine an accurate identification to the species level of the strains involved in Bc invasive infections in preterm neonates in France and study their virulome profile.Methods. The team performed WGS for 40 neonate clinical strains responsible for invasive infections in PN. A screening of virulence genes was performed to characterize strains associated with poor prognosis. Clinical data were collected and all clinical and genomic findings were analyzed for risk factors for death.

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Inclusion Criteria:

• Premature newborn (i.e born before 37 last menstrual periods) with invasive infection caused by B. cereus (strains isolated from blood culture and cerebrsopinal fluid)

Exclusion Criteria:

• None

The premature newborn included in the study were recruited from 14 NICU in 14 Tertiary Care center in France. This study is a national retrospective study