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37 papers found.
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A Prospective Investigation of Outcomes after Hospital Discharge for Endemic, Community-Acquired Methicillin-Resistant and -Susceptible Staphylococcus aureus Skin Infection

Arnold S. Bayer 0 1 5 0 Los Angeles Biomedical Research Institute, Harbor-University of California- Los Angeles Medical Center , Torrance 1 Received 4 August 2006; accepted 7 November 2006; electronically

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 ...

Bacteriophage Lysin Mediates the Binding of Streptococcus mitis to Human Platelets through Interaction with Fibrinogen

The binding of bacteria to human platelets is a likely central mechanism in the pathogenesis of infective endocarditis. We have previously found that platelet binding by Streptococcus mitis SF100 is mediated by surface components encoded by a lysogenic bacteriophage, SM1. We now demonstrate that SM1-encoded lysin contributes to platelet binding via its direct interaction with ...

Clinical and Epidemiologic Characteristics Cannot Distinguish Community-Associated Methicillin-Resistant Staphylococcus aureus Infection from Methicillin-Susceptible S. aureus Infection: A Prospective Investigation

Background. Community-associated (CA) methicillin-resistant Staphylococcus aureus (MRSA) infection has become common worldwide. Some researchers have argued that empirical therapy for MRSA should be given only to patients with suspected CA S. aureus infections who have risk factors for acquisition of MRSA. However, there are no prospective data examining this approach. Methods. We ...

Combination Antibiotic Therapy for Infective Endocarditis

Despite the availability of new and potent antibiotics, modern echocardiography, and advanced surgical techniques, infective endocarditis (IE) is still associated with high morbidity and mortality rates. Use of synergistic antibiotic combinations is an appealing way to optimize therapy for IE. This review focuses on evidence-based recommendations for combination antimicrobial ...

Daptomycin Resistance in Enterococci Is Associated with Distinct Alterations of Cell Membrane Phospholipid Content

Background The lipopeptide antibiotic, daptomycin (DAP) interacts with the bacterial cell membrane (CM). Development of DAP resistance during therapy in a clinical strain of Enterococcus faecalis was associated with mutations in genes encoding enzymes involved in cell envelope homeostasis and phospholipid metabolism. Here we characterized changes in CM phospholipid profiles ...

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 ...

Divergent Responses of Different Endothelial Cell Types to Infection with Candida albicans and Staphylococcus aureus

Endothelial cells are important in the pathogenesis of bloodstream infections caused by Candida albicans and Staphylococcus aureus. Numerous investigations have used human umbilical vein endothelial cells (HUVECs) to study microbial-endothelial cell interactions in vitro. However, the use of HUVECs requires a constant supply of umbilical cords, and there are significant ...

Editorial Commentary: Surgical Therapy for Staphylococcus aureus Prosthetic Valve Endocarditis: Proceed With Caution (Caveat Emptor)

Adolf W. Karchmer 1 Arnold S. Bayer () 0 0 Harbor-UCLA Medical Center, David Geffen School of Medicine, University of California , Los Angeles 1 Beth Israel Deaconess Medical Center, Harvard Medical

Emergence of Daptomycin Resistance in Daptomycin-Naïve Rabbits with Methicillin-Resistant Staphylococcus aureus Prosthetic Joint Infection Is Associated with Resistance to Host Defense Cationic Peptides and mprF Polymorphisms

Background Previous studies of both clinically-derived and in vitro passage-derived daptomycin–resistant (DAP-R) Staphylococcus aureus strains demonstrated the coincident emergence of increased DAP MICs and resistance to host defense cationic peptides (HDP-R). Methods In the present investigation, we studied a parental DAP-susceptible (DAP-S) methicillin-resistant Staphylococcus ...

Enhanced Expression of dltABCD Is Associated with the Development of Daptomycin Nonsusceptibility in a Clinical Endocarditis Isolate of Staphylococcus aureus

Using isogenic clinical bloodstream Staphylococcus aureus strains from a patient with relapsing endocarditis, we investigated the transcriptional profiles of the mprF and dlt genes in the context of cell-surface charge and daptomycin nonsusceptibility. As in prior studies, a point mutation within mprF was observed in the daptomycin-nonsusceptible strain. However, neither the ...

Evolving Resistance Among Gram-positive Pathogens

Antimicrobial therapy is a key component of modern medical practice and a cornerstone for the development of complex clinical interventions in critically ill patients. Unfortunately, the increasing problem of antimicrobial resistance is now recognized as a major public health threat jeopardizing the care of thousands of patients worldwide. Gram-positive pathogens exhibit an immense ...

Factors Influencing Time to Vancomycin-Induced Clearance of Nonendocarditis Methicillin-Resistant Staphylococcus aureus Bacteremia: Role of Platelet Microbicidal Protein Killing and agr Genotypes

Background. Vancomycin susceptibility, the accessory gene global regulator (agr) genotype and function, staphylococcal cassette chromosome (SCC) mec type, and susceptibility to cationic thrombin-induced platelet microbicidal protein 1 (tPMP-1) have been individually predictive of duration of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. This investigation evaluated ...

Failure of High-Dose Daptomycin for Bacteremia Caused by Daptomycin-Susceptible Enterococcus faecium Harboring LiaSR Substitutions

High-dose daptomycin (DAP) therapy failed in a neutropenic patient with bloodstream infection caused by a DAP-susceptible Enterococcus faecium (minimum inhibitory concentration, 3 µg/mL) harboring genetic changes associated with DAP resistance, with persistent bacteremia and selection of additional resistances. Daptomycin monotherapy should be used cautiously against ...

In Vitro Resistance to Thrombin-Induced Platelet Microbicidal Protein in Isolates of Staphylococcus aureus from Endocarditis Patients Correlates with an Intravascular Device Source

Platelet microbicidal proteins (PMPs) are small antimicrobial peptides secreted by mammalian platelets. In vitro resistance of Staphylococcus aureus strains to PMPs correlates with more extensive disease in experimental infective endocarditis (IE). To determine whether this same relationship exists in human S. aureus IE, we evaluated the in vitro PMP susceptibility phenotype of ...

Increased Cell Wall Teichoic Acid Production and D-alanylation Are Common Phenotypes among Daptomycin-Resistant Methicillin-Resistant Staphylococcus aureus (MRSA) Clinical Isolates

Multiple mechanisms have been correlated with daptomycin-resistance (DAP-R) in Staphylococcus aureus. However, one common phenotype observed in many DAP-R S. Aureus strains is a thickened cell wall (CW). The first evidence for an impact of CW-linked glycopolymers on this phenotype was recently demonstrated in a single, well-characterized DAP-R methicillin-susceptible S. aureus ...

Influence of the Timing of Cardiac Surgery on the Outcome of Patients With Infective Endocarditis and Stroke

Background. The timing of cardiac surgery after stroke in infective endocarditis (IE) remains controversial. We examined the relationship between the timing of surgery after stroke and the incidence of in-hospital and 1-year mortalities. Methods. Data were obtained from the International Collaboration on Endocarditis–Prospective Cohort Study of 4794 patients with definite IE who ...

Inhibition of Intracellular Macromolecular Synthesis in Staphylococcus aureus by Thrombin-Induced Platelet Microbicidal Proteins

Thrombin-induced platelet microbicidal proteins (tPMP-1 and tPMP-2) are believed to initiate their staphylocidal effects via cytoplasmic membrane perturbation. The aim of the present study was to investigate the role of subsequent inhibition of macromolecular synthesis in the staphylocidal mechanisms of tPMP-1 and tPMP-2 in an isogenic tPMP-susceptible and -resistant strain pair ...