Staphylococcus aureus
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PROVIDER: PRJNA135079 | ENA |
REPOSITORIES: ENA
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Project description:Objectives: Development of daptomycin resistance (DAPR) in Staphylococcus aureus is associated with clinical treatment failures. Mechanism(s) of such resistance has not been clearly defined. Methods: We studied an isogenic daptomycin-susceptible (DAPS) and daptomycin-resistant (DAPR) S. aureus strain pair (616; 701) from a patient with relapsing endocarditis during daptomycin treatment, using comparative transcriptomic and proteomic techniques. Results. Minor differences in genome content were found between strains by DNA hybridization. Transcriptomic analyses identified a number of genes differentially expressed in important functional categories: cell division, metabolism of bacterial envelopes and global regulation. Of note, the DAPR isolate exhibited reduced expression of the major cell wall autolysis gene coincident with upregulation of genes involved in wall teichoic acid production. Using quantitative (q)RT-PCR on gene cadre putatively involved in cationic peptide resistance, we formulated a putative regulatory network compatible with microarray data-sets, mainly implicating bacterial envelopes. Of interest, qRT-PCR of this same gene cadre from two distinct isogenic DAPS/DAPR clinical strain pairs revealed evidence of other strain dependent networks operative in the DAPR phenotype. Comparative proteomics of 616 vs 701 revealed differential abundance of proteins in various functional categories including: cell-wall associated targets and biofilm-formation proteins. Phenotypically, strains 616 and 701 showed major differences in ability to develop bacterial biofilms in presence of the antibacterial lipid, oleic acid. Conclusions: Compatible with previous in vitro observations, in vivo acquired DAPR in S. aureus is a complex, multistep phenomenon allowing for: i) strain dependent phenotypes; ii) transcriptome adaptation; and iii) modification of lipid and protein content of cellular envelopes. Daptomycin suceptible strain vs daptomycin non suceptible strain after daptomycin treatment
2011-12-02 | E-GEOD-28632 | biostudies-arrayexpress
Project description:Gene expression analysis of Linezolid resistance in various clinical Stapyloccoccus aureus strains.
| PRJNA135037 | ENA
Project description:Objectives: Development of daptomycin resistance (DAPR) in Staphylococcus aureus is associated with clinical treatment failures. Mechanism(s) of such resistance has not been clearly defined. Methods: We studied an isogenic daptomycin-susceptible (DAPS) and daptomycin-resistant (DAPR) S. aureus strain pair (616; 701) from a patient with relapsing endocarditis during daptomycin treatment, using comparative transcriptomic and proteomic techniques. Results. Minor differences in genome content were found between strains by DNA hybridization. Transcriptomic analyses identified a number of genes differentially expressed in important functional categories: cell division, metabolism of bacterial envelopes and global regulation. Of note, the DAPR isolate exhibited reduced expression of the major cell wall autolysis gene coincident with upregulation of genes involved in wall teichoic acid production. Using quantitative (q)RT-PCR on gene cadre putatively involved in cationic peptide resistance, we formulated a putative regulatory network compatible with microarray data-sets, mainly implicating bacterial envelopes. Of interest, qRT-PCR of this same gene cadre from two distinct isogenic DAPS/DAPR clinical strain pairs revealed evidence of other strain dependent networks operative in the DAPR phenotype. Comparative proteomics of 616 vs 701 revealed differential abundance of proteins in various functional categories including: cell-wall associated targets and biofilm-formation proteins. Phenotypically, strains 616 and 701 showed major differences in ability to develop bacterial biofilms in presence of the antibacterial lipid, oleic acid. Conclusions: Compatible with previous in vitro observations, in vivo acquired DAPR in S. aureus is a complex, multistep phenomenon allowing for: i) strain dependent phenotypes; ii) transcriptome adaptation; and iii) modification of lipid and protein content of cellular envelopes.
2011-12-02 | GSE28632 | GEO
Project description:Staphylococcus aureus is a notorious bacterial pathogen that causes a broad range of human diseases, and isolates that are resistant to several antibiotic classes including last resort antibiotics like vancomycin and daptomycin complicate the situation. We characterized S. aureus VC40, a strain that shows full resistance to vancomycin (MIC of 64 µg/ml) and daptomycin (MIC of 4 µg/ml) as well as a decreased susceptibility to further cell wall active agents. Genome sequencing revealed mutations in genes encoding the histidine kinases WalK and VraS that control cell envelope related processes and gene expression profiling indicated the induction of the respective regulons in strain VC40. Reconstitution of the mutations in walK or vraS into the susceptible S. aureus NCTC 8325 background resulted in a considerably increased resistance to vancomycin and daptomycin with MICs surpassing the clinical breakpoints for these antibiotics, thereby generating vancomycin-intermediate S. aureus (VISA) strains. As observed for S. aureus VC40, the walKwalk and vraS mutations also led to an increased expression of the respective regulons in the NCTC 8325 background. Phenotypic studies showed that S. aureus VC40 as well as the walKwalk and vraS mutants of strain NCTC 8325 were characterized by a significantly thickened cell wall, a decreased growth rate, a reduced autolytic activity and an increased resistance to lysostaphin-induced lysis. These results demonstrate that the WalK and VraS histidine kinases act as major switches which allow S. aureus to rapidly develop vancomycin resistance up to the VISA level via mutation of one single gene locus and concomitantly contribute to cross-resistance to other antibiotics including the last resort antibiotic daptomycin.
2014-08-18 | GSE46887 | GEO
Project description:Gene expression analysis of Oxacilin resistance in Stapyloccoccus aureus strains: 923 and V3
| PRJNA135095 | ENA
Project description:Daptomycin is a lipopeptide antibiotic that has recently been approved for treatment of Gram-positive bacterial infections. The mode of action of daptomycin is not yet entirely clear. To further understand the mechanism transcriptomic analysis of changes in gene expression in daptomycin-treated Staphylococcus aureus was carried out. The expression profile indicated that cell wall stress stimulon member genes (B. J. Wilkinson, A. Muthaiyan, and R. K. Jayaswal. 2005. Curr. Med. Chem. Anti-Infective Agents 4: 259-276) were significantly induced by daptomycin, and by the cell wall-active antibiotics vancomycin and oxacillin. Comparison of the daptomycin response of a two-component cell wall stress stimulon regulator VraSR mutant, S. aureus KVR, to its parent N315 showed diminished expression of the cell wall stress stimulon in the mutant. Daptomycin has been proposed to cause membrane depolarization, and the transcriptional responses to carbonyl cyanide m-chlorophenylhydrazone (CCCP) and nisin were determined. Transcriptional profiles of the responses to these antimicrobial agents showed significantly different patterns compared to those of the cell wall-active antibiotics, including little or no induction of the cell wall stress stimulon. However, there were a significant number of genes induced by both CCCP and daptomycin that were not induced by oxacillin or vancomycin, such that the daptomycin transcriptome was probably reflecting a membrane depolarizing activity of this antimicrobial also. The results indicate that inhibition of peptidoglycan biosynthesis, either directly or indirectly, and membrane depolarization are parts of the mode of action of daptomycin. Keywords: mode of action, transcriptional profiling
2007-12-25 | GSE9494 | GEO
Project description:Gene expression analysis of Vancomycin resistance in Stapyloccoccus aureus strains: PA, C1 and T8.
| PRJNA136851 | ENA
Project description:Daptomycin is an extensively used anti-staphylococcal agent due to the rise in methicillin-resistant Staphylococcus aureus. However, both laboratory-derived and clinical decreased susceptibility isolates have been described, but the mechanism(s) of resistance is poorly understood. To further understand daptomycin resistance, comparative genome sequencing, transcriptomics, ultrastructure ,and cell envelope studies were carried out on two relatively higher level (4 and 8 ug/ml-1) laboratory-derived daptomycin-resistant strains (strains CB1541 and CB1540 respectively) compared to their methicillin-resistant parent strain (CB1118;MW2). Genes altered in their expression common to both transcriptomes included some involved in glycine betaine accumulation, mscL, ure genes, femH, spa and smpB. However, the CB1541 transcriptome was further characterized by upregulation of various heat shock chaperone and protease genes, consistent with a mutation in clpP, and lytM and sceD. Both strains showed slow growth, and strongly decreased autolytic activity that appeared to be mainly due to decreased autolysin production. In contrast to previous common findings, we did not find any mutations in phospholipid biosynthesis genes, and it appears there are multiple pathways to and factors in daptomycin resistance.
2012-10-01 | GSE40753 | GEO
Project description:Staphylococcus aureus is a notorious bacterial pathogen that causes a broad range of human diseases, and isolates that are resistant to several antibiotic classes including last resort antibiotics like vancomycin and daptomycin complicate the situation. We characterized S. aureus VC40, a strain that shows full resistance to vancomycin (MIC of 64 M-BM-5g/ml) and daptomycin (MIC of 4 M-BM-5g/ml) as well as a decreased susceptibility to further cell wall active agents. Genome sequencing revealed mutations in genes encoding the histidine kinases WalK and VraS that control cell envelope related processes and gene expression profiling indicated the induction of the respective regulons in strain VC40. Reconstitution of the mutations in walK or vraS into the susceptible S. aureus NCTC 8325 background resulted in a considerably increased resistance to vancomycin and daptomycin with MICs surpassing the clinical breakpoints for these antibiotics, thereby generating vancomycin-intermediate S. aureus (VISA) strains. As observed for S. aureus VC40, the walKwalk and vraS mutations also led to an increased expression of the respective regulons in the NCTC 8325 background. Phenotypic studies showed that S. aureus VC40 as well as the walKwalk and vraS mutants of strain NCTC 8325 were characterized by a significantly thickened cell wall, a decreased growth rate, a reduced autolytic activity and an increased resistance to lysostaphin-induced lysis. These results demonstrate that the WalK and VraS histidine kinases act as major switches which allow S. aureus to rapidly develop vancomycin resistance up to the VISA level via mutation of one single gene locus and concomitantly contribute to cross-resistance to other antibiotics including the last resort antibiotic daptomycin. Microarray was used to evaluate alteration in the transcriptome of mutS mutant and compared to the parental strain VC40
2014-08-18 | E-GEOD-46887 | biostudies-arrayexpress
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