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ABSTRACT:
PROVIDER: PRJNA660878 | ENA |
REPOSITORIES: ENA
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Project description:The opportunistic pathogen Staphylococcus aureus is carried asymptomatically by about one-third of the human population. Body sites known to be colonized by S. aureus are the skin, nasopharynx and gut. In particular, the mechanisms that allow S. aureus to pass the gut epithelial barrier and to invade the bloodstream are poorly understood. Therefore, our present study was aimed at investigating possible differences between gut-colonizing and bacteremia isolates of S. aureus. To this end, 74 gut-colonizing isolates from healthy individuals and 144 blood-culture isolates were characterized by whole-genome sequencing. Subsequently, the cellular and extracellular proteomes of six representative isolates were examined by mass spectrometry. Lastly, the virulence potential of these isolates was evaluated using infection models based on human gut epithelial cells, blood cells, and a small animal infection model. Intriguingly, our results show that gut-colonizing and bacteremia isolates with the same sequence type (ST1 or ST5) are very similar at the genomic and proteomic levels. Nonetheless, they display differences in virulence, but gut-colonizing isolates may be more virulent than bacteremia isolates and vice versa. Importantly, we show that the main decisive factor preventing infection of gut epithelial cells in vitro is the presence of a tight barrier. Based on our present observations, we propose that the integrity of the gut epithelial layer, rather than the pathogenic potential of a gut-colonizing S. aureus strain, is the main decisive factor that determines whether this colonizer will become an invasive pathogen.
2023-03-11 | PXD030971 | Pride
Project description:Panton-valentine leukocidin (PVL) has been linked to worldwide emergence of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) -- its role in virulence in unclear. Here we show that PVL had no effect on global gene expression of prominent CA-MRSA strains nor did it affect bacterial clearance from lungs, spleen and kidneys in a highly discriminatory rabbit bacteremia model. These findings negate a large body of epidemiological research that implicated PVL in CA-MRSA virulence. Keywords: mutant vs wild type in 2 different growth phases grown in 2 different medias
2008-09-12 | GSE8677 | 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:Investigation of baseline transcription activity of two different clinical isolates of Staphylococcus aureus with two different susceptibility levels to the antibiotics Vancomycin and Daptomycin.
2012-08-03 | GSE39868 | GEO
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:Investigation of baseline transcription activity of two different clinical isolates of Staphylococcus aureus with two different susceptibility levels to the antibiotics Vancomycin and Daptomycin. Two different strains of Staphylococcus aureus, one that is fully Vancomycin and Daptomycin Sensitive and one with decreased Vancomycin and Daptomycin Sensitivity - grown to mid-log phase in rich broth.
2012-08-03 | E-GEOD-39868 | 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: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:PNBX were collected from 99 patients treated in the VA Greater Los Angeles (GLA-VA) Healthcare System between 2000-2016
2020-03-26 | GSE147493 | GEO