Project description:Genomic Insights of Salmonella, Virulence Markers, Antimicrobial Resistance, Phylogenetic Relatedness from Chicken Eggs in Saudi Arabia
Project description:A collection of 61 Salmonella enterica serovar Typhimurium (S. Typhimurium) of animal and human origin, matched as closely as possible by phage type, antimicrobial resistance pattern and place / time of isolation, and sourced from farms or hospitals in Scotland, were analysed by antimicrobial susceptibility testing, phage typing, pulsed field gel electrophoresis (PFGE), plasmid profiling and DNA microarrays. PFGE of all 61 isolates revealed ten PFGE profiles, which clustered by phage type and antibiotic resistance pattern, with human and animal isolates distributed between PFGE profiles. Analysis of 23 representative S. Typhimurium strains hybridised to a composite Salmonella DNA microarray identified a small number of specific regions of genome variation between different phage types and PFGE profiles. These variable regions of DNA were typically located within prophage-like elements. Simple PCR assays were subsequently designed to discriminate between different isolates from the same geographical region.
Project description:Multidrug-resistant (MDR; resistance to >3 antimicrobial classes) Salmonella enterica serovar I 4,[5],12:i:- strains were linked to a 2015 foodborne outbreak from pork. Strain USDA15WA-1, associated with the outbreak, harbors an MDR module and the metal tolerance element Salmonella Genomic Island 4 (SGI-4). Characterization of SGI-4 revealed that conjugational transfer of SGI-4 resulted in the mobile genetic element (MGE) replicating as a plasmid or integrating into the chromosome. Tolerance to copper, arsenic, and antimony compounds was increased in Salmonella strains containing SGI-4 compared to strains lacking the MGE. Following Salmonella exposure to copper, RNA-seq transcriptional analysis demonstrated significant differential expression of diverse genes and pathways, including induction of numerous metal tolerance genes (copper, arsenic, silver, and mercury). Evaluation of swine administered elevated concentrations of zinc oxide (2,000 mg/kg) and copper sulfate (200 mg/kg) as an antimicrobial feed additive (Zn+Cu) in their diet for 4 weeks prior to and 3 weeks post-inoculation with serovar I 4,[5],12:i:- indicated that Salmonella shedding levels declined at a slower rate in pigs receiving in-feed Zn+Cu compared to control pigs (no Zn+Cu). The presence of metal tolerance genes in MDR Salmonella serovar I 4,[5],12:i:- may provide benefits for environmental survival or swine colonization in metal-containing settings.
Project description:Poultry products are an important source of Salmonella enterica. An effective way to reduce food poisoning due to Salmonella would be to breed chickens more resistant to Salmonella. Unfortunately resistance to Salmonella is a complex trait with many factors involved. To learn more about Salmonella resistance mechanisms in young chickens, a cDNA microarray analysis was performed to compare gene expression profiles between a Salmonella susceptible and a more resistant chicken line. Newly hatched chickens were orally infected with S. enterica serovar Enteritidis. Since the intestine is the first barrier the bacteria encountersbacteria encounter after oral inoculation, gene expression was investigated in the intestine, from day 1 until day 21 post infection. Differences in gene expression between the susceptible and resistant chicken line were found in control as well as Salmonella infected conditions. In response to the Salmonella infection, the expression of different sets of genes seemed to be affected in the jejunum of the two chicken lines. In the susceptible line this included genes that affect T-cell activation, whereas in the more resistant line, at day 1, macrophage activation seemed to be more affected. At day 7 and 9 most gene expression differences between the two chicken lines were identified under control conditions, indicating a difference in the intestinal development between the two chicken lines which might be linked to the difference in Salmonella susceptibility. The findings in this study have lead to the identification of novel genes and possible cellular pathways of the host involved in Salmonella susceptibility. Keywords: timecourse, disease
Project description:The antimicrobial action of the curing agent NaNO2, which is added as a preservative to raw meat products, depends on its conversion to nitric oxide and other reactive nitrogen species under acidic conditions. In this study, we applied RNA-sequencing to analyze the acidified NaNO2 shock and adaptive response of Salmonella Typhimurium, a frequent contaminant in raw meat. Upon a 10 minute exposure to 150 mg/l NaNO2 in LB pH 5.5 acidified with lactic acid, genes involved in nitrosative stress protection together with several other stress related genes were induced. To the contrary, genes involved in translation, transcription, replication and motility were down-regulated. Induction of stress tolerance and reduction of cell proliferation obviously promote survival under harsh acidified NaNO2 stress. The subsequent adaptive response was characterized by up-regulation of NsrR-regulated genes and iron-uptake systems and down-regulation of genes involved in anaerobic respiratory pathways. Strikingly, amino acid decarboxylase systems, which contribute to acid tolerance, displayed increased transcript levels in response to acidified NaNO2. The induction of systems known to be involved in acid resistance indicates a nitrite mediated increase of acid stress. Transcriptome of Salmonella Typhimurium 14028, treated at OD600 = 0.80-0.85 with 150 mg/l NaNO2 (acidified by lactic acid in the growth medium) for 10 min (shock response) or until an OD600 = 1.45-1.55 is reached (1.5 - 2.0 h, adaptation response), was compared to respective control cultures without NaNO2. Amplified cDNA libraries for sequencing on the SOLiD 5500xl system were prepared from one culture per condition.
Project description:Screen for differences in gene expression between a parental Salmonella enterica serovar Enteritidis strain (ATCC4931) and an adapted strain with increased resistance to the widely used antimicrobial sanitizer dodecyltrimethylammonium chloride (DTAC)
Project description:The antimicrobial action of the curing agent NaNO2, which is added as a preservative to raw meat products, depends on its conversion to nitric oxide and other reactive nitrogen species under acidic conditions. In this study, we applied RNA-sequencing to analyze the acidified NaNO2 shock and adaptive response of Salmonella Typhimurium, a frequent contaminant in raw meat. Upon a 10 minute exposure to 150 mg/l NaNO2 in LB pH 5.5 acidified with lactic acid, genes involved in nitrosative stress protection together with several other stress related genes were induced. To the contrary, genes involved in translation, transcription, replication and motility were down-regulated. Induction of stress tolerance and reduction of cell proliferation obviously promote survival under harsh acidified NaNO2 stress. The subsequent adaptive response was characterized by up-regulation of NsrR-regulated genes and iron-uptake systems and down-regulation of genes involved in anaerobic respiratory pathways. Strikingly, amino acid decarboxylase systems, which contribute to acid tolerance, displayed increased transcript levels in response to acidified NaNO2. The induction of systems known to be involved in acid resistance indicates a nitrite mediated increase of acid stress.
Project description:Transcriptional profiling of jejunum infected with Salmonella in three different chicken lines early in life. Samples were taken at 8, 24 and 48 hours post infection. Salmonella was orally ingested at day zero (hatch).