Project description:The genus Cronobacter (formerly called Enterobacter sakazakii) is composed of five species; C. sakazakii, C. malonaticus, C. turicensis, C. muytjensii, and C. dublinensis. The genus includes opportunistic human pathogens, and the first three species have been associated with neonatal infections. The most severe diseases are caused in neonates and include fatal necrotizing enterocolitis and meningitis. The genetic basis of the diversity within the genus is unknown, and few virulence traits have been identified. We report here the first sequence of a member of this genus, C. sakazakii strain BAA-894. The genome of Cronobacter sakazakii strain BAA-894 comprises a 4.4 Mb chromosome (57% GC content) and two plasmids; 31 Kb (51% GC) and 131 Kb (56% GC). The genome was used to construct a 385,000 probe oligonucleotide tiling DNA microarray covering the whole genome. Comparative genomic hybridization (CGH) was undertaken on five other C. sakazakii strains, and representatives of the four other Cronobacter species. Among 4,382 annotated genes inspected in this study, about 55% of genes were common to all C. sakazakii strains and 43% were common to all Cronobacter strains, with 10 - 17% absence of genes. CGH highlighted 15 clusters of genes in C. sakazakii BAA-894 that were divergent or absent in more than half of the tested strains; six of these are of probable prophage origin. Putative virulence factors were identified in these prophage and in other variable regions. A number of genes unique to Cronobacter species associated with neonatal infections (C. sakazakii, C. malonaticus and C. turicensis) were identified. These included a copper and silver resistance system known to be linked to invasion of the blood-brain barrier by neonatal meningitic strains of Escherichia coli. In addition, genes encoding for multidrug efflux pumps and adhesins were identified that were unique to C. sakazakii strains from outbreaks in neonatal intensive care units. Comparative genomic hybridization highlighted 15 clusters of genes in C. sakazakii BAA-894 that were divergent or absent in more than half of the tested strains; six of these are of probable prophage origin. Putative virulence factors were identified in these prophage and in other variable regions. A number of genes unique to Cronobacter species associated with neonatal infections (C. sakazakii, C. malonaticus and C. turicensis) were identified. These included a copper and silver resistance system known to be linked to invasion of the blood-brain barrier by neonatal meningitic strains of Escherichia coli. In addition, genes encoding for multidrug efflux pumps and adhesins were identified that were unique to C. sakazakii strains from outbreaks in neonatal intensive care units. Ten Cronobacter samples were analyzed, including total genomic DNA of six C. sakazakii strains, one C. malonaticus strain, one C. muytjensii strain, one C. dublinensis strain and one C. turicensis strain.
Project description:The genus Cronobacter (formerly called Enterobacter sakazakii) is composed of five species; C. sakazakii, C. malonaticus, C. turicensis, C. muytjensii, and C. dublinensis. The genus includes opportunistic human pathogens, and the first three species have been associated with neonatal infections. The most severe diseases are caused in neonates and include fatal necrotizing enterocolitis and meningitis. The genetic basis of the diversity within the genus is unknown, and few virulence traits have been identified. We report here the first sequence of a member of this genus, C. sakazakii strain BAA-894. The genome of Cronobacter sakazakii strain BAA-894 comprises a 4.4 Mb chromosome (57% GC content) and two plasmids; 31 Kb (51% GC) and 131 Kb (56% GC). The genome was used to construct a 385,000 probe oligonucleotide tiling DNA microarray covering the whole genome. Comparative genomic hybridization (CGH) was undertaken on five other C. sakazakii strains, and representatives of the four other Cronobacter species. Among 4,382 annotated genes inspected in this study, about 55% of genes were common to all C. sakazakii strains and 43% were common to all Cronobacter strains, with 10 - 17% absence of genes. CGH highlighted 15 clusters of genes in C. sakazakii BAA-894 that were divergent or absent in more than half of the tested strains; six of these are of probable prophage origin. Putative virulence factors were identified in these prophage and in other variable regions. A number of genes unique to Cronobacter species associated with neonatal infections (C. sakazakii, C. malonaticus and C. turicensis) were identified. These included a copper and silver resistance system known to be linked to invasion of the blood-brain barrier by neonatal meningitic strains of Escherichia coli. In addition, genes encoding for multidrug efflux pumps and adhesins were identified that were unique to C. sakazakii strains from outbreaks in neonatal intensive care units. Comparative genomic hybridization highlighted 15 clusters of genes in C. sakazakii BAA-894 that were divergent or absent in more than half of the tested strains; six of these are of probable prophage origin. Putative virulence factors were identified in these prophage and in other variable regions. A number of genes unique to Cronobacter species associated with neonatal infections (C. sakazakii, C. malonaticus and C. turicensis) were identified. These included a copper and silver resistance system known to be linked to invasion of the blood-brain barrier by neonatal meningitic strains of Escherichia coli. In addition, genes encoding for multidrug efflux pumps and adhesins were identified that were unique to C. sakazakii strains from outbreaks in neonatal intensive care units.
Project description:Cronobacter sakazakii is a xerotolerant neonatal pathogen epidemiologically linked to powdered infant food formula, often leading to high mortality rates. Here, we used RNA-seq to provide physiological and transcriptional insights into the survival of C. sakazakii in desiccated conditions. Our RNA-seq data shows that about 22% of the total C. sakazakii genes were significantly up-regulated and 9% were down-regulated during desiccation survival. When qRT-PCR was used to validate the RNA-seq data, we found that the primary desiccation response was gradually down-regulated during the tested four hours of desiccation while the secondary response remained constitutively up-regulated. The desiccation tolerance of C. sakazakii was dependent on the immediate microenvironment surrounding the bacterial cell. Removal of TSB salts and that the introduction of sterile infant formula residues in the microenvironment enhanced the desiccation survival of C. sakazakii SP291. The trehalose biosynthetic pathway encoded by otsA and otsB, a prominent secondary bacterial desiccation response, was highly up-regulated in desiccated C. sakazakii. C. sakazakii SP291 ∆otsAB was significantly inhibited compared to the wild type in an eight hour desiccation survival assay confirming the physiological importance of trehalose in desiccation survival. Overall, we provide a comprehensive RNA-seq based transcriptional overview and the phenotypic importance of trehalose metabolism in Cronobacter sakazakii during desiccation.
Project description:Cronobacter sakazakii is a foodborne opportunistic pathogen that causes pneumonia, meningitis and bacteremia. To understand the acidic regulated and two component system PmrA/PmrB about strain pathogenesis, transcriptomics analysis of C. sakazakii grown under acidic pH 5.0 was performed by using RNA-sequencing.
Project description:Cronobacter sakazakii is well-known for its desiccation tolerance in the powdered infant formula (PIF) food production environment and the bacterium has been linked with high fatality rates in neonates who consume contaminated product. In this study, using deep-level RNA-sequencing, differentially expressed genes were studied in C. sakazakii ATCCTM29544 grown in simulated low-moisture environment designed to mimic the PIF production environment. Desiccation of bacteria was carried out on stainless steel coupons from which total RNA was subsequently recovered and sequenced. During 4 h of desiccation from the early stationary phase (ESP) grown culture, an approximately 3 log10 reduction was recorded for C. sakazakii viable cell count, with the largest change in viable cells occurring between desiccation hour 1 and 2 during which the culture medium was completely dried. Transcriptomic data obtained after 4 h of desiccation highlighted several highly-up regulated osmotolerance-related genes which were associated with the secondary response mechanism. These actively expressed genes mainly modulate pathways that synthetize glycine betaine and trehalose as well as the transport of these two and other compatible solutes. Understanding the activities of these genes and pathways will assist the development of technologies that mitigate the survival of C. sakazakii in the PIF production process.