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:Methicillin-resistant Staphylococcus aureus is one of the major causative agents associated to infections with a high morbidity and mortality in hospitals worldwide. In previous studies, we reported that lignan 3'-demethoxy-6-O-demethylisoguaiacin isolated and characterized from Larrea tridentata showed the best activity towards methicillin-resistant S. aureus. Understanding of mechanism of action of drugs allows design drugs in a better way. Therefore, we employed microarray to obtain gene expression profile of methicillin-resistant S. aureus after exposure to 3'-demethoxy-6-O-demethylisoguaiacin. The results showed that lignan had an effect on cell membrane affecting proteins of the ATP-binding cassette (ABC) transport system causing bacteria death. This study consisted of comparison of isolated RNA of MRSA not treated and MRSA treated with lignan 3'-demethoxy-6-O-demethylisoguaiacin. Both RNAs samples were differentially dyed with Cy3 and Cy5 during cDNA synthesis and hybridized on DNA chip. Afterwards, the chip was scanned in a GenePix 4000B scanner. The resulting gene expression profile was analyzed in databases for functional annotations to find a potential mechanism of the lignan in MRSA.
Project description:This project is intended to study the metabolic adaptation of Methicillin-Resistant Staphylococcus aureus (MRSA) to host immunity. Because of the nature of the samples RTI RCMRC worked with Dr. Anthony R. Richardson so that the samples would be extracted at the University of North Carolina at Chapel Hill under the condition that were optimized by RTI RCMRC for broad spectrum metabolomics analysis.
Project description:Whole-genome analysis by 62-strain microarray showed variation in resistance and virulence genes on mobile genetic elements (MGEs) between 40 isolates of methicillin-resistant Staphylococcus aureus (MRSA) strain CC22-SCCmecIV but also showed (i) detection of two previously unrecognized MRSA transmission events and (ii) that 7/8 patients were infected with a variant of their own colonizing isolate. [Data is also available from http://bugs.sgul.ac.uk/E-BUGS-128]
Project description:Staphylococcus aureus has been recognized as an important cause of human disease for more than 100 years. Resistance to multiple classes of antibiotics is becoming an increasingly difficult problem in the management of methicillin-resistant S. aureus (MRSA) and vancomycin-intermediate resistant S. aureus (VISA) infections. One approach to the MRSA and VISA problem, involves the discovery and development of new natural antimicrobials. The antimicrobial properties of essential oils of plant origin have been recognized for many years. In this study 0.1% of commercial cold pressed terpeneless Valencia orange oil (CPV) showed inhibitory and lytic activity against MRSA and VISA. To identify the mechanisms of action of CPV genomic response of CPV treated MRSA was analyzed by transcriptional profiling. Results showed alteration in the expression of cell wall peptidoglycan biosynthesis associated genes in the CPV treated cells. Transmission electron microscopic observation of CPV treated MRSA cells exhibited cell wall damage and cell lysis. Overall results of this study suggest that CPV may be a potential anti-staphylococcal agent for MRSA.
Project description:Purpose: Staphylococcus aureus is a highly successful human pathogen responsible for wide range of infections. In this study, we provide insights into the virulence, pathogenicity, and antimicrobial resistance determinants of methicillin susceptible and methicillin resistant Staphylococcus aureus (MSSA; MRSA) recovered from non-healthcare environments. Experiment design: Three environmental MSSA and three environmental MRSA were selected for proteomic profiling using iTRAQ MS/MS. Gene Ontology (GO) Annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) Pathway Annotation were applied to interpret the functions of the proteins detected. Results: 792 proteins were identified in MSSA and MRSA. Comparative analysis of MRSA and MSSA revealed that 8 of out 792 proteins were up-regulated and 156 down-regulated. Differentially abundant proteins were predominantly involved in catalytic and binding activity. Among 164 proteins that had differences in abundance, 29 proteins were involved in pathogenesis, antimicrobial activities,stress response, mismatch repair and cell wall synthesis. Twenty-two proteins associated with pathogenicity, including spa, sbi, clfA and dlt were up-regulated in MRSA. Moreover, the up-regulated pathogenic protein entC2 in MSSA was determined to be a super antigen potentially capable of triggering toxic shock syndrome in the host. Conclusions: Enhanced pathogenicity, antimicrobial activity and stress response were observed in MRSA compared to MSSA.
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:Methicillin-resistant Staphylococcus aureus (MRSA) is a highly prioritized pathogen proposed by World Health Organization (WHO). It is listed to encourage researchers to search for effective antimicrobial agents. Previously, we isolated soil Brevibacillus sp. strain SPR19, which showed anti-MRSA activity. However, the active substances were still unknown. This study aimed to isolate and identify the anti-MRSA substances from this bacterium. The cell-free supernatant of SPR19 was subjected to salt precipitation, cation exchange, and re-versed-phase chromatography. Bioassay-guided fractionation was used to screen active sub-stances
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.