The Identification, Antibiotic Resistance, Virulence Characteristics, and Genome Analysis of Cronobacter spp. Isolated from Infant Rice Cereal in Nanchang, China.

Cronobacter spp. are well known to be resistant to osmotic and dry stresses and can persist in a variety of foods. C. sakazakii and C. malonaticus are currently considered to be the primary pathogenic species that cause severe diseases. There are few studies on the prevalence of Cronobacter spp. in infant rice cereal. Information on the diversity, pathogenicity, and virulence of Cronobacter species obtained from foods is still relatively scarce and fragmentary. In this article, a total of 67 Cronobacter spp. strains were isolated from infant rice cereal in Nanchang, China. Forty-seven strains of C. sakazakii and 11 strains of C. malonaticus were identified by polymerase chain reaction (PCR). The resistance to 10 antibiotics was analyzed, showing that all isolates were sensitive except two strains. PCR detection for the five virulence genes (cpa, aut, hly, inv, and sip) and whole genome sequencing were performed. Co-existence of CSA or CMA with ampH was found in C. sakazakii and C. malonaticus strains. Compared with C. sakazakii, C. malonaticus lacked various virulence genes including yeeJ, stjC, and nanAKT genes. Another important observation was the presence of csg in the C. malonaticus genomes, while it was not found in the C. sakazakii. Notably, STs 1, 7, and 4, which are frequently associated with clinical infections, were observed. C. sakazakii and C. malonaticus strains induced higher apoptosis rate in Caco-2 cell in comparison with other Cronobacter species.