Role for IRAK-4 and p38 in Neutrophil Signaling in Response to Bacterial Lipoproteins from Staphylococcus aureus.

Neutrophils, polymorphonuclear leukocytes (PMN), express numerous pattern recognition receptors, including TLRs, capable of recognizing a wide variety of pathogens. Receptor engagement initiates a cascade of PMN responses with some occurring in seconds, and some requiring de novo protein synthesis over the course of many hours. Although numerous species of bacteria and bacterial products have been shown to activate PMN via TLRs, the signaling intermediates required for distinct PMN responses have not been well-defined in human PMN.

Androgens at the skin surface regulate pathogenesis through the activation of quorum sensing.

Unlabelled: the most frequent cause of skin infections, is more common in men than women and selectively colonizes the skin during inflammation. Yet, the specific cues that drive infection in these settings remain unclear. Here we show that the host androgens testosterone and dihydrotestosterone promote pathogenesis and skin infection.

The influenza-injured lung microenvironment promotes MRSA virulence, contributing to severe secondary bacterial pneumonia.

Influenza infection is substantially worsened by the onset of secondary pneumonia caused by bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA). The bidirectional interaction between the influenza-injured lung microenvironment and MRSA is poorly understood. By conditioning MRSA ex vivo in bronchoalveolar lavage fluid collected from mice at various time points of influenza infection, we found that the influenza-injured lung microenvironment dynamically induces MRSA to increase cytotoxin expression while decreasing metabolic pathways.

Group B adaptation promotes survival in a hyperinflammatory diabetic wound environment.

Diabetic wounds have poor healing outcomes due to the presence of numerous pathogens and a dysregulated immune response. Group B (GBS) is commonly isolated from diabetic wound infections, but the mechanisms of GBS virulence during these infections have not been investigated. Here, we develop a murine model of GBS diabetic wound infection and, using dual RNA sequencing, demonstrate that GBS infection triggers an inflammatory response.

Cefadroxil Comparable to Cephalexin: Minimum Inhibitory Concentrations among Methicillin-Susceptible Staphylococcus aureus Isolates from Pediatric Musculoskeletal Infections.

Cephalexin and cefadroxil are oral first-generation cephalosporins used to treat methicillin-susceptible Staphylococcus aureus (MSSA) infections. Despite its shorter half-life, cephalexin is more frequently prescribed, although cefadroxil is an appealing alternative, given its slower clearance and possibility for less frequent dosing. We report comparative MIC distributions for cefadroxil and cephalexin, as well as for oxacillin, cephalothin, ceftaroline, and cefazolin, for 48 unique clinical MSSA isolates from pediatric patients with musculoskeletal infections.

Human monoclonal antibodies against surface antigens recognize in vitro and in vivo biofilm.

Implant-associated infections are difficult to treat because of biofilm formation. Bacteria in a biofilm are often insensitive to antibiotics and host immunity. Monoclonal antibodies (mAbs) could provide an alternative approach to improve the diagnosis and potential treatment of biofilm-related infections.

Lipoproteins from Drive Neutrophil Extracellular Trap Formation in a TLR2/1- and PAD-Dependent Manner.

Neutrophils, polymorphonuclear leukocytes (PMN), play a critical role in the innate immune response to , a pathogen that continues to be associated with significant morbidity and mortality. Neutrophil extracellular trap (NET) formation is involved in ensnaring and killing of , but this host-pathogen interaction also leads to host tissue damage. Importantly, NET components including neutrophil proteases are under consideration as therapeutic targets in a variety of disease processes.

Cathepsin G Degrades Staphylococcus aureus Biofilms.

Polymorphonuclear leukocytes (PMN) phagocytose and kill individual bacteria but are far less efficient when challenged with bacterial aggregates. Consequently, growth within a biofilm affords Staphylococcus aureus some protection but PMN penetrate S. aureus biofilms and phagocytose bacteria, suggesting that enzymes released through neutrophil degranulation degrade biofilms into fragments small enough for phagocytosis.

Staphylococcus epidermidis protease EcpA can be a deleterious component of the skin microbiome in atopic dermatitis.

Background: Staphylococcus aureus and Staphylococcus epidermidis are the most abundant bacteria found on the skin of patients with atopic dermatitis (AD). S aureus is known to exacerbate AD, whereas S epidermidis has been considered a beneficial commensal organism.

Objective: In this study, we hypothesized that S epidermidis could promote skin damage in AD by the production of a protease that damages the epidermal barrier.

Quorum Sensing, Virulence, and Antibiotic Resistance of USA100 Methicillin-Resistant Staphylococcus aureus Isolates.

Methicillin-resistant (MRSA) infections impact all patient populations both in the community and in health care settings. Despite advances in our knowledge of MRSA virulence, little is known about the regulatory mechanisms of USA100 health care-associated MRSA isolates, which are the second most frequently identified MRSA isolates found in all infections. This work focused on the contribution of the USA100 type II quorum-sensing system to virulence and antibiotic resistance.

Impact of Environmental Cues on Staphylococcal Quorum Sensing and Biofilm Development.

Staphylococci are commensal bacteria that colonize the epithelial surfaces of humans and many other mammals. These bacteria can also attach to implanted medical devices and develop surface-associated biofilm communities that resist clearance by host defenses and available chemotherapies. These communities are often associated with persistent staphylococcal infections that place a tremendous burden on the healthcare system.

ω-Hydroxyemodin limits staphylococcus aureus quorum sensing-mediated pathogenesis and inflammation.

Antibiotic-resistant pathogens are a global health threat. Small molecules that inhibit bacterial virulence have been suggested as alternatives or adjuncts to conventional antibiotics, as they may limit pathogenesis and increase bacterial susceptibility to host killing. Staphylococcus aureus is a major cause of invasive skin and soft tissue infections (SSTIs) in both the hospital and community settings, and it is also becoming increasingly antibiotic resistant.

Rot is a key regulator of Staphylococcus aureus biofilm formation.

Staphylococcus aureus is a significant cause of chronic biofilm infections on medical implants. We investigated the biofilm regulatory cascade and discovered that the repressor of toxins (Rot) is part of this pathway. A USA300 community-associated methicillin-resistant S.

Chronic ethanol feeding increases the severity of Staphylococcus aureus skin infections by altering local host defenses.

Alcoholics are at increased risk of Staphylococcus aureus skin infection and serious sequelae, such as bacteremia and death. Despite the association between alcoholism and severe S. aureus skin infection, the impact of EtOH on anti-S.

Polyhydroxyanthraquinones as quorum sensing inhibitors from the guttates of Penicillium restrictum and their analysis by desorption electrospray ionization mass spectrometry.

The endophytic fungus Penicillium restrictum was isolated from the stems of a milk thistle (Silybum marianum) plant. In culture, the fungus produced distinct red guttates, which have been virtually uninvestigated, particularly from the standpoint of chemistry. Hence, this study examined the chemical mycology of P.

Analysis of autoinducer-2 quorum sensing in Yersinia pestis.

The autoinducer-2 (AI-2) quorum-sensing system has been linked to diverse phenotypes and regulatory changes in pathogenic bacteria. In the present study, we performed a molecular and biochemical characterization of the AI-2 system in Yersinia pestis, the causative agent of plague. In strain CO92, the AI-2 signal is produced in a luxS-dependent manner, reaching maximal levels of 2.

Staphylococcus aureus nuclease is an SaeRS-dependent virulence factor.

Several prominent bacterial pathogens secrete nuclease (Nuc) enzymes that have an important role in combating the host immune response. Early studies of Staphylococcus aureus Nuc attributed its regulation to the agr quorum-sensing system. However, recent microarray data have indicated that nuc is under the control of the SaeRS two-component system, which is a major regulator of S.

Quorum quenching and antimicrobial activity of goldenseal (Hydrastis canadensis) against methicillin-resistant Staphylococcus aureus (MRSA).

The popular herbal remedy goldenseal (Hydrastis canadensis L.) is traditionally used to treat skin infections. With this study, we show activity of H.

The structure of LsrB from Yersinia pestis complexed with autoinducer-2.

The crystal structure of LsrB from Yersinia pestis complexed with autoinducer-2 (AI-2; space group P2(1)2(1)2(1), unit-cell parameters a = 40.61, b = 61.03, c = 125.

Nuclease modulates biofilm formation in community-associated methicillin-resistant Staphylococcus aureus.

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging contributor to biofilm-related infections. We recently reported that strains lacking sigma factor B (sigB) in the USA300 lineage of CA-MRSA are unable to develop a biofilm. Interestingly, when spent media from a USA300 sigB mutant was incubated with other S.