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PROVIDER: PRJNA1073721 | ENA |
REPOSITORIES: ENA
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Project description:Several methicillin resistance (SCCmec) clusters characteristic of hospital-associated methicillin-resistant Staphylococcus aureus (MRSA) strains harbor the psm-mec locus. In addition to encoding the cytolysin, phenol-soluble modulin (PSM) mec, this locus has been attributed gene regulatory functions. Here we employed genome-wide transcriptional profiling to define the regulatory function of the psm-mec locus. The immune evasion factor protein A emerged as the primary conserved and strongly regulated target of psm-mec, an effect we show is mediated by the psm-mec RNA. Furthermore, the psm-mec locus exerted regulatory effects that were more moderate in extent and possibly mediated by the PSM-mec peptide. For example, expression of PSM-mec limited expression of mecA, thereby decreasing methicillin resistance. Our study shows that the psm-mec locus has a rare dual regulatory RNA and encoded cytolysin function, both with the potential to enhance MRSA virulence. Furthermore, our findings reveal a specific mechanism underscoring the recently emerging concept that S. aureus strains balance pronounced virulence and high expression of antibiotic resistance.
2017-08-29 | GSE51366 | GEO
Project description:BACKGROUND: Infections with community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) are emerging worldwide. We investigated an outbreak of severe CA-MRSA infections in children following out-patient vaccination. METHODS AND FINDINGS: We carried out a field investigation after adverse events following immunization (AEFI) were reported. We reviewed the clinical data from all cases. S. aureus recovered from skin infections and from nasal and throat swabs were analyzed by pulse-field gel electrophoresis, multi locus sequence typing, PCR and microarray. In May 2006, nine children presented with AEFI, ranging from fatal toxic shock syndrome, necrotizing soft tissue infection, purulent abscesses, to fever with rash. All had received a vaccination injection in different health centres in one District of Ho Chi Minh City. Eight children had been vaccinated by the same health care worker (HCW). Deficiencies in vaccine quality, storage practices, or preparation and delivery were not found. Infection control practices were insufficient. CA-MRSA was cultured in four children and from nasal and throat swabs from the HCW. Strains from children and HCW were indistinguishable. All carried the Panton-Valentine leukocidine (PVL), the staphylococcal enterotoxin B gene, the gene complex for staphylococcal-cassette-chromosome mec type V, and were sequence type 59. Strain HCM3A is epidemiologically unrelated to a strain of ST59 prevalent in the USA, although they belong to the same lineage. CONCLUSIONS: We describe an outbreak of infections with CA-MRSA in children, transmitted by an asymptomatic colonized HCW during immunization injection. Consistent adherence to injection practice guidelines is needed to prevent CA-MRSA transmission in both in- and outpatient settings. Data is also available from http://bugs.sgul.ac.uk/E-BUGS-45
2009-01-16 | E-BUGS-45 | biostudies-arrayexpress
Project description:The epidemic character of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA), especially the geographically widespread clone USA300, is poorly understood. USA300 isolates carry a type IV staphylococcal chromosomal cassette mec (SCCmec) element conferring -lactam antibiotic class resistance and a putative pathogenicity island, ACME (arginine catabolic mobile element). Physical linkage between SCCmec and ACME suggests that selection for antibiotic resistance and for pathogenicity may be interconnected. We constructed isogenic mutants containing deletions of SCCmec and ACME in a USA300 clinical isolate to determine the role of these elements in a rabbit model of bacteremia. We found that deletion of type IV SCCmec did not affect competitive fitness, whereas deletion of ACME significantly attenuated pathogenicity or fitness of USA300. These data are consistent with a model in which ACME enhances growth and survival of USA300, allowing for genetic "hitchhiking" of SCCmec. SCCmec in turn protects against exposure to β -lactams. Keywords: Wild type control vs mutant Wild type untreated in triplicate is compared to three mutants in triplicate in both exponential and stationary growth phases, totalling 24 samples
2010-05-19 | E-GEOD-9308 | biostudies-arrayexpress
Project description:The epidemic character of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA), especially the geographically widespread clone USA300, is poorly understood. USA300 isolates carry a type IV staphylococcal chromosomal cassette mec (SCCmec) element conferring -lactam antibiotic class resistance and a putative pathogenicity island, ACME (arginine catabolic mobile element). Physical linkage between SCCmec and ACME suggests that selection for antibiotic resistance and for pathogenicity may be interconnected. We constructed isogenic mutants containing deletions of SCCmec and ACME in a USA300 clinical isolate to determine the role of these elements in a rabbit model of bacteremia. We found that deletion of type IV SCCmec did not affect competitive fitness, whereas deletion of ACME significantly attenuated pathogenicity or fitness of USA300. These data are consistent with a model in which ACME enhances growth and survival of USA300, allowing for genetic "hitchhiking" of SCCmec. SCCmec in turn protects against exposure to β -lactams. Keywords: Wild type control vs mutant
2008-09-30 | GSE9308 | GEO
Project description:The Staphylococcus aureus Panton Valentine leukocidin (PVL) is a pore-forming toxin secreted by strains epidemiologically associated with the current outbreak of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) and with the often lethal necrotizing pneumonia. To investigate the role of PVL in pulmonary disease, we tested the pathogenicity of clinical isolates, isogenic PVL-negative and PVL-positive S. aureus strains, as well as purified PVL, in a mouse acute pneumonia model. Here we show that PVL is sufficient to cause pneumonia and that the expression of this leukotoxin induces global changes in transcriptional levels of genes encoding secreted and cell-wall-anchored staphylococcal proteins, including the lung inflammatory factor staphylococcal protein A (Spa). Keywords: comparative transcription profile in the presence or absence of PVL toxin
2007-02-13 | GSE6985 | GEO
Project description:Evolutionary origin of the staphylococcal cassette chromosome mec (SCCmec)
| PRJEB18761 | ENA
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.
2015-06-27 | GSE70309 | GEO
Project description:Staphylococcus aureus is a Gram-positive human pathogen causing a variety of human diseases in both hospital and community settings. This bacterium is so closely associated with prophages that it is rare to find S. aureus isolates without prophages. Two phages are known to be important for staphylococcal virulence: the beta-hemolysin (hlb) converting phage and the Panton-Valentine Leukocidin (PVL) converting phage. The hlb-converting phage is found in more than 90% of clinical isolates of S. aureus. This phage produces exotoxins and immune modulatory molecules, which inhibit human innate immune responses. The PVL-converting phage produces the two-component exotoxin PVL, which can kill human leucocytes. This phage is wide-spread among community-associated methicillin resistant S. aureus (CA-MRSA). It also shows strong association with soft tissue infections and necrotizing pneumonia. Several lines of evidence suggest that staphylococcal prophages increase bacterial virulence not only by providing virulence factors but also by altering bacterial gene expression: 1) Transposon insertion into prophage regulatory genes, but not into the genes of virulence factors, reduced S. aureus killing of Caenorhabditis elegans.; 2) Although the toxins and immune modulatory molecules encoded by the hlb- converting phages do not function in the murine system, deletion of ϕNM3, the hlb-converting phage in S. aureus Newman, reduced staphylococcal virulence in the murine abscess formation model. 3) In a preliminary microarray experiment, prophages in S. aureus Newman altered the expression of more than 300 genes. In this research proposal, using microarray and high-throughput quantitative RT-PCR (qRT-PCR) technologies, we will identify the effects of the two important staphylococcal phages on the gene expression of S. aureus in both in vitro and in vivo conditions. This project is intended to be completed within one year. All the data – microarray, qRT-PCR and all the primer sequences- will be made available to public 6 month after completion. Data from this project will help us to understand the role of prophages in the S. aureus pathogenesis and can lead to development of a strategy to interfere with the pathogenesis process. Following strains were grown in TSA broth: Staphylococcus aureus USA300 (reference) Staphylococcus aureus USA300 with deletion of ϕSa2usa (Query) Staphylococcus aureus USA300 with deletion of ϕSa3usa (Query) Staphylococcus aureus USA300 Prophage-free mutant (Query) Staphylococcus aureus USA300 Prophage-free mutant lysogenized with ϕSa2mw (Query) Staphylococcus aureus USA300 Prophage-free mutant lysogenized with ϕSa3usa (Query) strain: Staphylococcus aureus USA300 Prophage-free mutant lysogenized with both ϕSa2mw and ϕSa3usa (Query) RNA samples were harvested at early log, midlog and stationary phase.Samples were hybridized on aminosilane coated slides with 70-mer oligos.
2011-02-28 | E-GEOD-26623 | biostudies-arrayexpress
Project description:Methicillin-resistant Staphylococcus aureus (MRSA) is problematic both in hospitals and the community. Currently, we have limited understanding of mechanisms of innate immune evasion used by S. aureus. To that end, we created an isogenic deletion mutant in strain MW2 (USA400) of the saeR/S two-component gene regulatory system and studied its role in mouse models of pathogenesis and during human neutrophil interaction. In this study, we demonstrate saeR/S plays a distinct role in S. aureus pathogenesis and is vital for virulence of MW2 in a mouse model of sepsis. Moreover, deletion of saeR/S significantly impaired survival of MW2 in human blood and after neutrophil phagocytosis. Microarray analysis of genes influenced by saeR/S demonstrated SaeR/S of MW2 influences a wide variety of genes with diverse biological functions. These data shed new insight into how virulence is regulated in S. aureus and associates a specific staphylococcal gene-regulatory system with invasive staphylococcal disease. Wild type control vs mutant at two different growth phases
2010-05-14 | E-GEOD-15067 | biostudies-arrayexpress
Project description:Hemolysins are lytic exotoxins expressed in most strains of S. aureus, but hemolytic activity varies between strains. We have previously reported several novel anti-virulence compounds that disrupt the S. aureus transcriptome, including hemolysin gene expression. This report delves further into our two lead compounds, loratadine and a structurally related brominated carbazole, and their effects on hemolysin production in methicillin-resistant S. aureus (MRSA). To gain understanding into how these compounds affect hemolysis, we analyzed these exotoxins at the DNA, RNA, and protein level after in vitro treatment. While lysis of red blood cells varied between strains, DNA sequence variation did not account for it. We hypothesized that our compounds would modulate gene expression of multiple hemolysins in two hospital-acquired strains of MRSA, both with staphylococcal cassette chromosome mec (SCCmec) type II. RNA-seq analysis of differential gene expression in untreated and compound-treated cultures revealed hundreds of differentially expressed genes, with a significant enrichment in genes involved in hemolysis. The brominated carbazole and loratadine both displayed the ability to reduce hemolysis in strain 43300 but displayed differential activity in strain USA100. These results corroborate gene expression studies as well as western blots of alpha hemolysin. Together, this work suggests that small molecules may alter exotoxin production in MRSA but that the directionality and/or magnitude of the difference are likely strain dependent.
2024-05-15 | GSE267020 | GEO