Project description:Previous studies have documented the diversity of genetic background of methicillin-resistant S. aureus (MRSA) strains associated with healthcare (HA-MRSA), community (CA-MRSA) and livestock (LA-MRSA). The accessory and core-variable genome content of those strains remain largely unknown. To compare the composition of accessory and core-variable genome of Belgian MRSA strains according to host, population setting and genetic background, representative strains of HA- (n=21), CA- (n = 13) and ST398 LA-MRSA (n = 18) were characterized by a DNA-microarray (StaphVar Array) composed of oligonucleotide probes targeting ~400 resistance, adhesion and virulence associated genes.ST398 strains displayed very homogenous hybridization profiles (>94% gene content homology) irrespective of their host origin. This “ST398-specific” genomic profile was not distantly demarked from those of certain human-associated lineages but lacked several virulence- and colonization-associated genes harbored by strains of human origin, such as genes encoding proteases, haemolysins or adhesins. No enterotoxin gene was found among ST398 strains. In conclusion, our findings are consistent with a non-human origin of this ST398 lineage but suggest that it might have the potential to adapt further to the human host. Overall design: CGH microarray was performed on epidemiologically distinct human and animal isolates of methicillin resistant S.aureus. S. aureus labeled genomic DNA were hybridized to StaphVar arrays containing 1326 60mer oligonucleotide probes (Eurogentec, Belgium).
Project description:Staphylococcus aureus is a common human and animal opportunistic pathogen. In humans nasal carriage of S. aureus is a risk factor for various infections. Methicillin-resistant S. aureus ST398 is highly prevalent in pigs in Europe and North America. The mechanism of successful pig colonization by MRSA ST398 is poorly understood. Previously, we developed a nasal colonization model of porcine nasal mucosa explants to identify molecular traits involved in nasal MRSA colonization of pigs. Here, we report the analysis of the transcriptome of MRSA ST398 strain S0462 during colonization on the explant epithelium. Major regulated genes were encoding metabolic processes and regulation of these genes represents metabolic adaptation to nasal mucosa explants. Colonization was not accompanied by significant changes in transcripts of main virulence associated genes or known human colonization factors. Here, we document regulation of two genes which have potential influence on S. aureus colonization; cysteine extracellular proteinase (scpA) and von Willebrand factor-binding protein (vwbp, located on SaPIbov5). Colonization with isogenic-deletion strains (Δvwbp and ΔscpA) did not alter the nasal S. aureus colonization compared to wild type. Our results suggest that nasal colonization with MRSA ST398 is a complex event that is accompanied with changes in bacterial gene expression regulation and metabolic adaptation. Number of the samples: 5 (timepoint 0 min, 30 min, 60 min, 90 min and 180 min) in 4 replicates. 4 control samples
Project description:There is evidence that MRSA ST398 of animal origin is only capable of temporarily occupying the human nose, and it is therefore, often considered a poor human colonizer.We inoculated 16 healthy human volunteers with a mixture of the human MSSA strain 1036 (ST931, CC8) and the bovine MSSA strain 5062 (ST398, CC398), 7 weeks after a treatment with mupirocin and chlorhexidine-containing soap. Bacterial survival was studied by follow-up cultures over 21 days. The human strain 1036 was eliminated faster (median 14 days; range 2-21 days) than the bovine strain 5062 (median 21 days; range 7-21 days) but this difference was not significant (p = 0.065). The bacterial loads were significantly higher for the bovine strain on day 7 and day 21. 4/14 volunteers (28.6%) showed elimination of both strains within 21 days. Of the 10 remaining volunteers, 5 showed no differences in bacterial counts between both strains, and in the other 5 the ST398 strain far outnumbered the human S. aureus strain. Within the 21 days of follow-up, neither human strain 1036 nor bovine strain 5062 appeared to acquire or lose any mobile genetic elements. In conclusion, S. aureus ST398 strain 5062 is capable of adequately competing for a niche with a human strain and survives in the human nose for at least 21 days. [Data is also available from http://bugs.sgul.ac.uk/E-BUGS-131]
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.
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. Overall design: S. aureus strains were cultivated in tryptic soy broth at 37℃ for 18hrs and harvested for RNA extraction and hybridization on Affymetrix microarrays.
Project description:Abstract Staphylococcus aureus of sequence type 398 has emerged in Europe, North America and Asia and has typically been associated with livestock and their human contacts. We analysed two PVL-negative t034-ST398 isolates from humans in contact with pigs, and two t034-ST398 PVL-positive isolates from two unrelated adopted Chinese children using multi-strain microarrays to determine the genomic variability. The ST398 isolates clearly belong to the same lineage when compared to other clonal lineages. However, the four isolates cluster into two distinct groups corresponding to differences in epidemiology based on mobile genetic elements and resistance patterns, suggesting the two groups are epidemiologically distinct. Data is also available from http://bugs.sgul.ac.uk/E-BUGS-84
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) 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. Overall design: RNA-Seq analysis was performed on log phase WT Staphylococcus aureus USA300 NRS384 grown at 30 degrees C and grown at 37 degrees C. Each condition was performed in triplicate thereby yielding a total of 6 samples for RNA-Seq analysis.
Project description:Staphylococcus aureus can cause serious skin, respiratory, and other life-threatening invasive infections in humans, and methicillin-resistant S. aureus (MRSA) strains have been acquiring increasing antibiotic resistance. While MRSA was once mainly considered a hospital-acquired infection, the emergence of new strains, some of which are pandemic, has resulted in community-acquired MRSA infections that often present as serious skin infections in otherwise healthy individuals. Accordingly, defining the mechanisms that govern the activation and regulation of the immune response to MRSA is clinically important and could lead to the discovery of much needed rational targets for therapeutic intervention. Because the cytokine thymic stromal lymphopoetin (TSLP) is highly expressed by keratinocytes of the skin3, we investigated its role in host-defense against MRSA. Here we demonstrate that TSLP acts on neutrophils to increase their killing of MRSA. In particular, we show that both mouse and human neutrophils express functional TSLP receptors. Strikingly, TSLP enhances mouse neutrophil killing of MRSA in both an in vitro whole blood killing assay and an in vivo skin infection model. Similarly, TSLP acts directly on purified human blood neutrophils to reduce MRSA burden. Unexpectedly, we demonstrate that TSLP mediates these effects both in vivo and in vitro by engaging the complement C5 system. Thus, TSLP increases MRSA killing in a neutrophil- and complement-dependent manner, revealing a key connection between TSLP and the innate complement system, with potentially important therapeutic implications for control of MRSA infection. Overall design: mRNA expression analysis. 16 samples are from 2 donors, 8 samples per donor, 2 time points (4hr and 16 hr), and 4 conditions (control, TSLP treated, Heat Killed MRSA treated, and TSLP+HKM treated) .