title: Genetic analysis of the Cronobacter sakazakii O4 to O7 O-antigen gene clusters and development of a PCR assay for identification of all C. sakazakii O serotypes.
abstract: The Gram-negative bacterium Cronobacter sakazakii is an emerging food-borne pathogen that causes severe invasive infections in neonates. Variation in the O-antigen lipopolysaccharide in the outer membrane provides the basis for Gram-negative bacteria serotyping. The O-antigen serotyping scheme for C. sakazakii, which includes seven serotypes (O1 to O7), has been recently established, and the O-antigen gene clusters and specific primers for three C. sakazakii serotypes (O1, O2, and O3) have been characterized. In this study, the C. sakazakii O4, O5, O6, and O7 O-antigen gene clusters were sequenced, and gene functions were predicted on the basis of homology. C. sakazakii O4 shared a similar O-antigen gene cluster with Escherichia coli O103. The general features and anomalies of all seven C. sakazakii O-antigen gene clusters were evaluated and the relationship between O-antigen structures and their gene clusters were investigated. Serotype-specific genes for O4 to O7 were identified, and a molecular serotyping method for all C. sakazakii O serotypes, a multiplex PCR assay, was developed by screening against 136 strains of C. sakazakii and closely related species. The sensitivity of PCR-based serotyping method was determined to be 0.01 ng of genomic DNA and 10(3) CFU of each strain/ml. This study completes the elucidation of C. sakazakii O-antigen genetics and provides a molecular method suitable for the identification of C. sakazakii O1 to O7 strains.
authors.affiliation: Nankai University, Tianjin, China.
authors.forename: Yamin
authors.initials: Y
authors.lastname: Sun
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.forename: Quan
authors.initials: Q
authors.lastname: Wang
authors.forename: Boyang
authors.initials: B
authors.lastname: Cao
authors.forename: Xin
authors.initials: X
authors.lastname: He
authors.forename: Kun
authors.initials: K
authors.lastname: Li
authors.forename: Lu
authors.initials: L
authors.lastname: Feng
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015373:Bacterial Typing Techniques / Q000379:methods*; D044083:Cronobacter sakazakii / Q000145:classification* / Q000235:genetics* / Q000276:immunology; D017931:DNA Primers / Q000235:genetics; D006801:Humans; D007231:Infant, Newborn; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D060885:Multiplex Polymerase Chain Reaction / Q000379:methods*; D019081:O Antigens / Q000737:chemistry / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA; D012703:Serotyping / Q000379:methods
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D019081:O Antigens