Project description:RNA from in vitro grown Salmonella typhimurium is compared with RNA extracted from Salmonella typhimurium from infected chick caecums using a common DNA reference. Keywords: Disease state analysis, infected versus uninfected, common reference
Project description:Salmonella Heidelberg is currently the 9th common serovar and has more than twice the average incidence of blood infections in Salmonella. A recent Salmonella Heidelberg outbreak in chicken infected 634 people during 2013-2014, with a hospitalization rate of 38% and an invasive illness rate of 15%. While the company’s history suggested longstanding sanitation issues, the strains’ characteristics which may have contributed to the outbreak are unknown. We hypothesized that the outbreak strains of S. Heidelberg might possess enhanced stress tolerance or virulence capabilities. Consequently, we obtained nine food isolates collected during the outbreak investigation and several reference isolates and tested their tolerance to processing stresses, their ability to form biofilms, and their invasiveness in vitro. We further performed RNA-sequencing on three isolates with varying heat tolerance to determine the mechanism behind our isolates’ enhanced heat tolerance. Ultimately, we determined that (i) many Salmonella Heidelberg isolates associated with a foodborne outbreak have enhanced heat resistance (ii) Salmonella Heidelberg outbreak isolates have enhanced biofilm-forming ability under stressful conditions, compared to the reference strain (iii) exposure to heat stress may also increase Salmonella Heidelberg isolates’ antibiotic resistance and virulence capabilities and (iv) Salmonella Heidelberg outbreak-associated isolates are primed to better survive stress and cause illness. This data helps explain the severity and scope of the outbreak these isolates are associated with and can be used to inform regulatory decisions on Salmonella in poultry and to develop assays to screen isolates for stress tolerance and likelihood of causing severe illness.
Project description:The present project investigates transcriptomics changes in laboratory mutants of Salmonella typhimurium SL1344 obtained by pre-exposure to biocides, including triclosan (TRI), benzalkonium chloride (BZC), and chlorexidine (CHX), and antibiotics including Ampicillin (AP) and ciprofloxacin (Cip), as well as in natural isolates selected for their resistance to these same biocides. Changes in gene expression were investigated using a 12k combimatrix customarray, design-based on the genome of SL1344 as well as a variety of genes of plasmid origins.
Project description:Transcriptional profiles of a chlorhexidine tolerant Salmonella Typhimurium were compared to its, chlorhexidine sensitive, isogenic progenitor isolate. RNA was extracted from mid-log phase cells from both isolates, without chlorhexidine exposure and following exposure to 1 µg/ ml of chlorhexidine for 30 minutes. Transcriptional profiles of the tolerant isolate were compared to the sensitive isolate, with and without chlorhexidine exposure. Carried out using 3 biological replicates for each sample; each sample hybridised in a two-channel hybridization against Salmonella genomic DNA as the comparator/reference
Project description:Salmonella enterica subsp. enterica contains more than 2,600 serovars of which four are of major medical relevance for humans. While the typhoidal serovars (Typhi and Paratyphi A) are human-restricted and cause enteric fever, non-typhoidal Salmonella serovars (Typhimurium and Enteritidis) have a broad host range and predominantly cause gastroenteritis. In this study, we compared the core proteomes of Salmonella Typhi, Paratyphi A, Typhimurium and Enteritidis using contemporary proteomics. Five isolates, covering different geographical origins, and one reference strain per serovar were grown in vitro to the exponential phase. Protein levels of orthologous proteins between serovars were compared and subjected to gene ontology term enrichment and inferred regulatory interactions. Differential expression of the core proteomes of the typhoidal serovars appears mainly related to cell surface components and, for the non-typhoidal serovars, to pathogenicity. Our findings may guide future development of novel diagnostics and vaccines, and understanding of disease progression.
Project description:Salmonella enterica serovar Typhimurium (S. Typhimurium) definitive phage type 104 (DT104) has caused significant morbidity and mortality in humans and animals for almost three decades. We have completed the full DNA sequence of one DT104 strain, NCTC13348 and show that the main differences between the genome of this isolate and the previously sequenced S. Typhimurium LT2 lie in integrated prophage elements and the Salmonella Genomic Island 1 encoding antibiotic resistance genes. Thirteen isolates of S. Typhimurium DT104 with different pulsed field gel electrophoresis (PFGE) profiles were analyzed by multi locus sequence typing (MLST), plasmid profiling, hybridization to a Pan-Salmonella DNA microarray and prophage-based multiplex PCR. All the isolates belonged to a single MLST type ST19. Microarray data demonstrated that the 13 DT104 isolates were remarkably conserved in gene content. The PFGE band-size differences in these isolates could be explained to a great extent by changes in prophage and plasmid content. Thus, here the nature of variation in different S. Typhimurium DT104 isolates is further defined at the genome level illustrating how this phage type is evolving over time.
Project description:RNA from in vitro grown Salmonella typhimurium is compared with RNA extracted from Salmonella typhimurium from infected chick caecums using a common DNA reference. Keywords: Disease state analysis, infected versus uninfected, common reference Five replicates from infected chick caecal contents compared to a common reference. Three replicates from in vitro grown Salmonella compared to a common reference. The common reference was genomic DNA and always occupies the Cy3 channel (channel 2).