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.
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:S. aureus ATCC 25923 is performance standard for antimicrobial susceptibility testing. S. aureus ATCC 33591 showed resistance against erytrhromycin, penicillin, and streptomycin. We used microarray to compare RNA expression between sensitive and resistant strain of S. aureus as a preliminary research for MRSA inhibition.
Project description:Resistant isolates of methicillin-resistant Staphylococcus aureus (MRSA) often cause infections with high rates of mortality. Antimicrobial peptides are source of molecules for new antimi-crobials development, such as melittin, a fraction of venom from Apis mellifera bee. The aims of this work were to evaluate antibacterial and antibiofilm activity of melittin and its association with oxa-cillin (meltoxa) on MRSA isolates and to investigate mechanisms of action on MRSA by using proteomic analysis.
Project description:Proteomic analysis of Staphylococcus aureus strain NCTC8325 (MRSA) grown in rich medium. This strain produces 97% of persister in stationary phase. Exponential and stationary phase MRSA were compared to elucidate pathways that are modulated in the persister state compared to dividing cells.
Project description:Methicillin resistant Staphylococcus aureus (MRSA) is an opportunistic pathogen chief amongst bloodstream infecting pathogens. MRSA produces an array of human specific virulence factors that may contribute to immune suppression. Here, we defined the response of primary human phagocytes to infection with MRSA using RNA-Seq. We found that the overall transcriptional response to MRSA was weak both in the number of genes and the magnitude of response. Using an ex vivo bacteremia model with fresh human blood, we found that infection with live MRSA resulted in the down-regulation of genes related to innate immune response, and cytokine and chemokine signaling. This muted transcriptional response was conserved across diverse S. aureus clones but absent in heat-killed MRSA or blood infected with live Staphylococcus epidermidis. Importantly, the muted signature was also present in patients with S. aureus bacteremia. We next identified the master regulator SaeRS and the SaeRS-regulated pore-forming toxins as key mediators of transcriptional suppression. The impaired chemokine and cytokine responses were reflected by circulating protein levels in the plasma. MRSA elicits a soluble milieu that is restrictive in the recruitment of human neutrophils compared to strains lacking saeRS. Thus, MRSA blunts the inflammatory response resulting in impaired neutrophil recruitment, which could promote the survival of S. aureus during invasive infection.
Project description:S. aureus ATCC 25923 is performance standard for antimicrobial susceptibility testing. S. aureus ATCC 33591 showed resistance against erytrhromycin, penicillin, and streptomycin. We used microarray to compare RNA expression between sensitive and resistant strain of S. aureus as a preliminary research for MRSA inhibition. S. aureus strains were cultivated in tryptic soy broth at 37℃ for 18hrs and harvested for RNA extraction and hybridization on Affymetrix microarrays.