Molecular Characterization of Cronobacter Lipopolysaccharide O-Antigen Gene Clusters and Development of Serotype-Specific PCR Assays

Abstract

ABSTRACT Cronobacter (formerly Enterobacter sakazakii ) is a recently defined genus consisting of six species, C. sakazakii , C. malonaticus , C. dublinensis , C. muytjensii , C. turicensis , and Cronobacter genomospecies 1. In this study, MboII restriction fragment length polymorphism (RFLP) patterns of O-antigen gene clusters, located between galF and gnd , were used to identify serotypes in Cronobacter spp. Seven O-antigen RFLP clusters were generated, including three C. sakazakii clusters, previously identified as serotypes O1, O2, and O3. The O-antigen regions of six strains with unique RFLP patterns, including two C. sakazakii strains, two C. malonaticus strains, one C. turicensis strain, and one C. muytjensii strain, revealed three O-antigen gene clusters shared among Cronobacter species. PCR assays were developed, targeting the wzx O-antigen polymerase gene, and used to screen 231 Cronobacter strains to determine the frequency of these newly identified serotypes.