Project description:The epidemic community-acquired methicillin-resistant S. aureus (CA-MRSA) clone USA300 has recently become a leading cause of hospital-associated bloodstream infections (BSI). Leveraging this recent introduction into hospitals and the limited genetic variation across the USA300 strains, we combined microbial comparative genomics with phenotypic analyses to discover adaptive mutations. USA300 isolates from BSI were found to have independently evolved single nucleotide variants in the transcriptional regulator sarZ. sarZ inactivation lead to altered expression of virulence factors, resulting in increased lethality in a murine model of BSI. Thus, USA300 strains can optimize their fitness in hospitals through evolution of higher virulence.
Project description:The study aims to compare gene expression patterns of Staphyloccoccus aureus USA300 vs USA300 sae knockout. Samples were hybridized on aminosilane coated slides with 70-mer oligos.
Project description:The study aims to compare gene expression patterns of Staphyloccoccus aureus USA300 vs USA300 sae knockout. Samples were hybridized on aminosilane coated slides with 70-mer oligos. 12 arrays total.
Project description:Methicillin-resistant Staphylococcus aureus (MRSA) is a major threat to human health. Rather than depend on creating new antibiotics (to which bacteria will eventually become resistant), we are employing antibiotic adjuvants that potentiation existing antibiotics. To gain biological insight into how lead compounds potentiate antibiotics and inhibit biofilms, we used RNA-seq on treated MRSA USA300 cultures to examine antibiotic adjuvant affects transcritome-wide.
Project description:Background: Community-associated methicillin-resistant staphylococcus aureus (CA-MRSA) is a drug-resistant bacterium prevalent in community settings, characterized by high pathogenicity and transmission potential. Polymorphonuclear neutrophils (PMNs) represent the first line of defense in innate immunity and are activated to phagocytose MRSA. However, MRSA, once phagocytosed by PMNs, induces necroptosis within the neutrophils, which is a key mechanism contributing to host damage.CA-MRSA releases virulence factors that enhance its pathogenicity by disrupting the host's innate immune response, particularly impairing the phagocytic function of PMNs. Steamed Panax notoginseng (S-PN) has demonstrated immune-regulatory and anti-inflammatory properties, showing promising therapeutic effects in alleviating the severe inflammatory responses induced by pathogenic microbial infections. Objective: This study aims to investigate the pharmacological effects and mechanisms of S-PN in attenuating CA-MRSA-induced necroptosis of PMNs, and to explore the impact of PMN necroptosis on the inflammatory response. Methods: A co-culture model of MRSA USA300 strain and PMNs isolated from healthy human blood was established to observe the changes in necroptosis marker HMGB1, PMNs counts, ROS, chemokine MCP-1 and pro-inflammatory cytokines IL-1β, IL-8, TNF-α. RNA-seq was employed to analyze the effects of S-PN on the transcriptional expression of pathogenesis-related genes of MRSA. RT-PCR was utilized to validate the expression of S-PN on MRSA virulence factors and PMNs necroptosis related genes. Results: S-PN significantly inhibited HMGB1, ROS, MCP-1, IL-1β and IL-8 in MRSA-PMN co-cultures, the PMN count in the S-PN group was higher than that in the model group. S-PN down-regulated MRSA pathogenic-associated Staphylococcus aureus infection and quorum sensing signaling pathways, and significantly reduced the virulence factors PSM and PVL. S-PN suppressed the expression of genes associated with necroptosis ripk1, ripk3, and mlkl in PMNs. Conclusion: S-PN inhibited CA-MRSA-induced necroptosis of PMNs, as well as the excessive inflammatory response and ROS accumulation accompanying this process. The mechanism involves the inhibition of the expression of MRSA virulence factor PSM and necroptosis pathway genes. These findings underscore the significant potential of S-PN in the treatment of CA-MRSA infections.
Project description:To trace the origin, evolution, and dissemination pattern of the USA300 CA-MRSA clone in France, we sequenced a collection of strains of this lineage from cases reported in France in the last decade and compared them with 431 ST8 strains from the USA.
Project description:Little is known about the expression of methicillin-resistant Staphylococcus aureus (MRSA) genes during infection conditions. Here, we described the transcriptome of the clinical MRSA strain USA300 derived from human cutaneous abscesses, and compared it with USA300 bacteria derived from infected kidneys in a mouse model. Remarkable similarity between the transcriptomes allowed us to identify genes encoding multiple proteases and toxins, and iron- and peptide-transporter molecules, which are upregulated in both infections and are likely important for establishment of infection. We also showed that disruption of the global transcriptional regulators agr and sae prevents in vivo upregulation of many toxins and proteases, protecting mice from lethal infection dose, and hinting at the role of these transcriptional regulators in the pathology of MRSA infection.
Project description:The study aims to compare gene expression patterns of Staphyloccoccus aureus USA300 wild type (reference) vs USA300 agr knockout(query). The agr quorum sensing system is an important regulator of density dependent gene expression. To determine the role of agr in USA300 virulence a agr mutant was constructed and differential gene expression compared to the parental wildtype.