Advanced search    

Search: authors:"Ambrose L. Cheung"

9 papers found.
Use AND, OR, NOT, +word, -word, "long phrase", (parentheses) to fine-tune your search.

Improving Transformation of Staphylococcus aureus Belonging to the CC1, CC5 and CC8 Clonal Complexes

Methicillin resistant Staphylococcus aureus (MRSA) is an opportunistic pathogen found in hospital and community environments that can cause serious infections. A major barrier to genetic manipulations of clinical isolates has been the considerable difficulty in transforming these strains with foreign plasmids, such as those from E. coli, in part due to the type I and IV Restriction ...

Sigma Factor SigB Is Crucial to Mediate Staphylococcus aureus Adaptation during Chronic Infections

Staphylococcus aureus is a major human pathogen that causes a range of infections from acute invasive to chronic and difficult-to-treat. Infection strategies associated with persisting S. aureus infections are bacterial host cell invasion and the bacterial ability to dynamically change phenotypes from the aggressive wild-type to small colony variants (SCVs), which are adapted for ...

Selective Chemical Inhibition of agr Quorum Sensing in Staphylococcus aureus Promotes Host Defense with Minimal Impact on Resistance

M. Alexander Jon K. Femling Brian M. Gray Frank R. DeLeo Michael Otto Ambrose L. Cheung Bruce S. Edwards Larry A. Sklar Alexander R. Horswill Pamela R. Hall Hattie D. Gresham Eric P. Skaar

Disparity in the In Vitro versus In Vivo Regulation of Fibronectin-Binding Proteins by 2 Global Regulators, saeRS and sigB, in Staphylococcus aureus

Fibronectin-binding protein A plays an important role in Staphylococcus aureus endovascular infections. We characterized the sigB-saeRS-fnbA expression network with fibronectin binding in vitro and in an experimental infective endocarditis (IE) model using parental strains RN6390 and SH1000 and their respective isogenic saeRS mutants. In contrast to the in vitro data, there was no ...

Neutrophil-derived IL-1β Is Sufficient for Abscess Formation in Immunity against Staphylococcus aureus in Mice

Neutrophil abscess formation is critical in innate immunity against many pathogens. Here, the mechanism of neutrophil abscess formation was investigated using a mouse model of Staphylococcus aureus cutaneous infection. Gene expression analysis and in vivo multispectral noninvasive imaging during the S. aureus infection revealed a strong functional and temporal association between ...

Role of mgrA and sarA in Methicillin-Resistant Staphylococcus aureus Autolysis and Resistance to Cell Wall-Active Antibiotics

Background. We have previously shown the importance of mgrA and sarA in controlling autolysis of Staphylococcus aureus, with MgrA and SarA both being negative regulators of murein hydrolases.Methods. In this study, we analyzed the effects of mgrA and sarA on antibiotic-mediated lysis in vitro and on the responses to cell wall-active antibiotic therapy in an experimental ...

Regulation of Staphylococcus aureus α-Toxin Gene (hla) Expression by agr, sarA and sae In Vitro and in Experimental Infective Endocarditis

BackgroundThe Staphylococcus aureus global regulators—agr, sarA and sae—coordinately control α-toxin gene (hla) expression in vitro. However, their relative in vivo contributions to hla expression, particularly in endovascular infections, have not been defined MethodsA plasmid-based hla-promoter:green fluorescent protein reporter system was constructed in 2 genetically related S. ...

A Mouse Model of Post-Arthroplasty Staphylococcus aureus Joint Infection to Evaluate In Vivo the Efficacy of Antimicrobial Implant Coatings

Background Post-arthroplasty infections represent a devastating complication of total joint replacement surgery, resulting in multiple reoperations, prolonged antibiotic use, extended disability and worse clinical outcomes. As the number of arthroplasties in the U.S. will exceed 3.8 million surgeries per year by 2030, the number of post-arthroplasty infections is projected to ...

Activation and Transcriptional Interaction between agr RNAII and RNAIII in Staphylococcus aureus In Vitro and in an Experimental Endocarditis Model

This study compared the promoter activation profiles of the 2 major transcripts of the Staphylococcus aureus global regulon, agr (RNAII and RNAIII). In vitro, RNAIII activation temporally followed RNAII activation and was absent in agr mutants. In experimental endocarditis, maximal RNAII activation in vegetations occurred early, followed by progressive increases in RNAIII ...