Cronobacter sakazakii can cause severe life-threatening invasive infections in neonates, with a high mortality rate mostly associated with powdered infant formula consumption. The study describes a fatal C. sakazakii infection in premature infant fed only with expressed human milk. Despite the identification of etiological factor from patient's blood, the epidemiological investigation, including mother's skin, hospital surfaces, milk expressing devices, and milk samples, did not show bacterial contamination. The infection was caused by C. sakazakii ST1, being one of the leading genotypes reported in invasive infections. The phylogenetic analysis of the international collection of the ST1 organisms allowed us to identify the isolate as a member of the main cluster. The pathogenic potential of the isolate was augmented by the presence of IncFIB-like molecule representing virulence plasmids of pESA-3 family. Isolate presented ESBL phenotype associated with blaSHV-12 gene harboured by IncX3 plasmid. The described case gave valuable information to genetics of Cronobacter, and also urges the need of wider whole-genome sequencing implementation as a part of diagnostic procedure.
Keywords: Cronobacter sakazakii; ST1; WGS; neonatal infection; whole genome sequencing.