Project description:Methicillin-resistant Staphylococcus aureus (MRSA) infections result in more than 200,000 hospitalizations and 10,000 deaths in the United States each year and remain an important medical challenge. A key factor of S. aureus pathogenesis is the production of virulence proteins that are secreted into the extracellular matrix damaging host tissues and forming abscesses that may serve as replicative niches for the bacteria. We recently discovered that host-derived cis-unsaturated fatty acids activate the transcription and translation of EsxA, a protein that plays a central role in abscess formation in clinically relevant MRSA strains. Additionally, we discovered that fatty acid stimulation of EsxA is dependent on fakA, a gene that encodes a protein responsible for the incorporation of exogenous fatty acids into the S. aureus phospholipid membrane. In order to gain a comprehensive understanding of host-fatty-acid-sensing in S. aureus, we performed RNA-Seq analysis on WT Staphylococcus aureus USA300 NRS384, a community-acquired MRSA strain, in the presence and absence of 10μM linoleic acid.
Project description:We report the miRNA profile of murine macrophages (cell line: RAW264.7) after supplementation with polyunsaturated fatty acids (PUFA) and stimulation with LTA. The fatty acids docosahexaenoic acid (DHA, C22:6n3) or arachidonic acid (AA, C20:4n6) were included in the culture medium in concentrations of 15 µmol/L using ethanol as a vehicle (0.2 % v/v final ethanol concentration). Cells were cultured in the enriched media totaling 72 h. Stimulation of cells was performed in the last 24 h of fatty acid supplementation by addition of LTA (0.5 µg/mL; from Staphylococcus aureus).
Project description:Staphylococcus aureus is an important food poisoning bacterium. In food preservation, acidification is a well-known method. Permeant weak organic acids, like lactic and acetic acids, are known to be more effective against bacteria than inorganic strong acids (e.g., HCl). Growth experiments and metabolic and transcriptional analyses were used to determine the responses of a food pathogenic S. aureus strain exposed to lactic acid, acetic acid, and HCl at pH 4.5. Lactic and acetic acid stress induced a slower transcriptional response and large variations in growth patterns compared with the responses induced by HCl. In cultures acidified with lactic acid, the pH of the medium gradually increased to 7.5 during growth, while no such increase was observed for bacteria exposed to acetic acid or HCl. Staphylococcus aureus increased the pH in the medium mainly through accumulation of ammonium and the removal of acid groups, resulting in increased production of diacetyl (2,3-butanedione) and pyrazines. The results showed flexible and versatile responses of S. aureus to different types of acid stress. As measured by growth inhibition, permeant organic acid stress introduced severe stress compared with the stress caused by HCl. Cells exposed to lactic acid showed specific mechanisms of action in addition to sharing many of the mechanisms induced by HCl stress. Data is also available from http://bugs.sgul.ac.uk/E-BUGS-87
Project description:Young adult fer-15;fem-1 Caenorhabditis elegans were infected with Staphylococcus aureus for 8 h to determine the transcriptional host response to Staphylococcus aureus. Analysis of differential gene expression in C. elegans young adults exposed to two different bacteria: E. coli strain OP50 (control), wild-type Staphylococcus aureus RN6390. Samples were analyzed at 8 hours after exposure to the different bacteria. These studies identified C. elegans genes induced by pathogen infection. Keywords: response to pathogen infection, innate immunity, host-pathogen interactions
Project description:We report the transcriptome profile of murine macrophages (cell line: RAW264.7) after supplementation with polyunsaturated fatty acids (PUFA) and stimulation with LTA. The fatty acids docosahexaenoic acid (DHA, C22:6n3) or arachidonic acid (AA, C20:4n6) were included in the culture medium in concentrations of 15 µmol/L using ethanol as a vehicle (0.2 % v/v final ethanol concentration). Cells were cultured in the enriched media totaling 72 h. Stimulation of cells was performed in the last 24 h of fatty acid supplementation by addition of LTA (0.5 µg/mL; from Staphylococcus aureus).
Project description:A triclosan-ciprofloxacin cross-resistant mutant strain of Staphylococcus aureus displays an alteration in the expression of several cell membrane structural and functional genes. Triclosan is an antimicrobial agent found in many consumer products. Several studies have demonstrated that triclosan inhibits the bacterial fatty acid biosynthetic enzyme, enoyl-ACP reductase (FabI). Studies have also demonstrated that decreased susceptibility to triclosan correlates with ciprofloxacin resistance in several bacteria. In these bacteria, resistance to both drugs maps to genes encoding multi-drug efflux pumps. The focus of this study was to determine whether triclosan resistance contributes to ciprofloxacin resistance in Staphylococcus aureus. Gene expression profiling was performed to compare the gene expression profiles of unexposed and triclosan-exposed wild-type and JJ5 determined that an alteration in global gene expression possibly resulting in a change in cell membrane structure and function is likely responsible for triclosan and ciprofloxacin resistance in JJ5. Keywords: Treatment response
Project description:A triclosan-ciprofloxacin cross-resistant mutant strain of Staphylococcus aureus displays an alteration in the expression of several cell membrane structural and functional genes. Triclosan is an antimicrobial agent found in many consumer products. Several studies have demonstrated that triclosan inhibits the bacterial fatty acid biosynthetic enzyme, enoyl-ACP reductase (FabI). Studies have also demonstrated that decreased susceptibility to triclosan correlates with ciprofloxacin resistance in several bacteria. In these bacteria, resistance to both drugs maps to genes encoding multi-drug efflux pumps. The focus of this study was to determine whether triclosan resistance contributes to ciprofloxacin resistance in Staphylococcus aureus. Gene expression profiling was performed to compare the gene expression profiles of unexposed and triclosan-exposed wild-type and JJ5 determined that an alteration in global gene expression possibly resulting in a change in cell membrane structure and function is likely responsible for triclosan and ciprofloxacin resistance in JJ5. Keywords: Treatment response WT and triclosan resistant mutant were treated with triclosan and their gene expression was compared to their untreated conterparts.
Project description:In the present study, we employed Affymetrix Staphylococcus aureus GeneChip arrays to investigate the dynamics of global gene expression profiles during the cellular response of Staphylococcus aureus to peracetic acid, which involved initial growth inhibition and subsequent partial recovery. Keywords: Time course
Project description:Methicillin-resistant Staphylococcus aureus (MRSA) infections result in more than 200,000 hospitalizations and 10,000 deaths in the United States each year and remain an important medical challenge. To better understand the transcriptome of Staphylococcus aureus USA300 NRS384, a community-acquired MRSA strain, we have conducted an RNA-Seq experiment on WT samples.