Growth of Staphylococcus aureus in the presence of oleic acid shifts the glycolipid fatty acid profile and increases resistance to antimicrobial peptides.

Staphylococcus aureus readily adapts to various environments and quickly develops antibiotic resistance, which has led to an increase in multidrug-resistant infections. Hence, S. aureus presents a significant global health issue and its adaptations to the host environment are crucial for understanding pathogenesis and antibiotic susceptibility.

Lipidomics of homeoviscous adaptation to low temperatures in utilizing exogenous straight-chain unsaturated fatty acids.

Unlabelled: It is well established that can incorporate exogenous straight-chain unsaturated fatty acids (SCUFAs) into membrane phospho- and glyco-lipids from various sources in supplemented culture media and when growing during infection. Given the enhancement of membrane fluidity when oleic acid (C18:1Δ9) is incorporated into lipids, we were prompted to examine the effect of medium supplementation with C18:1Δ9 on growth at low temperatures. C18:1Δ9 supported the growth of a cold-sensitive, branched-chain fatty acid (BCFA)-deficient mutant at 12°C.

Defective contributes to increased membrane fluidity and cell wall thickening in with high-level daptomycin resistance.

Unlabelled: Daptomycin is a membrane-targeting last-resort antimicrobial therapeutic for the treatment of infections caused by methicillin- and/or vancomycin-resistant . In the rare event of failed daptomycin therapy, the source of resistance is often attributable to mutations directly within the membrane phospholipid biosynthetic pathway of or in the regulatory systems that control cell envelope response and membrane homeostasis. Here we describe the structural changes to the cell envelope in a daptomycin-resistant isolate of strain N315 that has acquired mutations in the genes most commonly reported associated with daptomycin resistance: , , and .

Growth of in the presence of oleic acid shifts the glycolipid fatty acid profile and increases resistance to antimicrobial peptides.

readily adapts to various environments and quickly develops antibiotic resistance, which has led to an increase in multidrug-resistant infections. Hence, presents a significant global health issue and its adaptations to the host environment are crucial for understanding pathogenesis and antibiotic susceptibility. When is grown conventionally, its membrane lipids contain a mix of branched-chain and straight-chain saturated fatty acids.

Lipidomics of homeoviscous adaptation to low temperatures in utilizing exogenous straight-chain unsaturated fatty acids over biosynthesized endogenous branched-chain fatty acids.

It is well established that can incorporate exogenous straight-chain unsaturated fatty acids (SCUFAs) into membrane phospho- and glyco-lipids from various sources in supplemented culture media, and when growing in an infection. Given the enhancement of membrane fluidity when oleic acid (C18:1Δ9) is incorporated into lipids, we were prompted to examine the effect of medium supplementation with C18:1Δ9 on growth at low temperatures. C18:1Δ9 supported the growth of a cold-sensitive, branched-chain fatty acid (BCFA)-deficient mutant at 12°C.

Defective pgsA contributes to increased membrane fluidity and cell wall thickening in S. aureus with high-level daptomycin resistance.

Daptomycin is a membrane-targeting last-resort antimicrobial therapeutic for the treatment of infections caused by methicillin- and/or vancomycin-resistant . In the rare event of failed daptomycin therapy, the source of resistance is often attributable to mutations directly within the membrane phospholipid biosynthetic pathway of or in the regulatory systems that control cell envelope response and membrane homeostasis. Here we describe the structural changes to the cell envelope in a daptomycin-resistant isolate of strain N315 that has acquired mutations in the genes most commonly reported associated with daptomycin-resistance: , , and .

Transcriptomic and Metabolomic Analysis of a Fusidic Acid-Selected Mutant of .

Physiological experimentation, transcriptomics, and metabolomics were engaged to compare a fusidic acid-resistant mutant SH10001st-2 to its parent strain SH1000. SH10001st-2 harbored a mutation (H457Y) in the gene which encodes the fusidic acid target, elongation factor G, as well as mutations in a putative phage gene of unknown function. SH10001st-2 grew slower than SH1000 at three temperatures and had reduced coagulase activity, two indicators of the fitness penalty reported for -mediated fusidic acid- resistance in the absence of compensatory mutations.

Fluorescence Polarization (FP) Assay for Measuring Staphylococcus aureus Membrane Fluidity.

Fluorescence polarization is a method to determine membrane fluidity using a hydrophobic fluorescent dye that intercalates into the fatty acid bilayer. A spectrofluorometer is used to polarize UV light as a vertical excitation beam which passes through the dye-labeled membrane where the dye fluoresces. The beams perpendicular and horizontal to the excitation light are then collected and analyzed.

(Adenine Phosphoribosyltransferase) Mutation in Laboratory-Selected Vancomycin-Intermediate .

Comparative genomic sequencing of laboratory-derived vancomycin-intermediate (VISA) (MM66-3 and MM66-4) revealed unique mutations in both MM66-3 (in and ), and MM66-4 (in and ), compared to hetero-VISA parent strain MM66. Transcriptional profiling revealed that both MM66 VISA shared 79 upregulated genes and eight downregulated genes. Of these, 30.

Revealing Fatty Acid Heterogeneity in Staphylococcal Lipids with Isotope Labeling and RPLC-IM-MS.

Up to 80% of the fatty acids in membrane lipids are branched, rather than straight-chain, fatty acids. The branched fatty acids (BCFAs) may have either an even or odd number of carbons, and the branch position may be at the penultimate carbon () or the antepenultimate () carbon of the tail. This results in two sets of isomeric fatty acid species with the same number of carbons that cannot be resolved by mass spectrometry.

Patient and caregiver engagement in the Patient-Centered Outcomes Research Institute (PCORI) Health Care Horizon Scanning System (HCHSS) process.

Objective: The Patient-Centered Outcomes Research Institute (PCORI) horizon scanning system is an early warning system for healthcare interventions in development that could disrupt standard care. We report preliminary findings from the patient engagement process.

Methods: The system involves broadly scanning many resources to identify and monitor interventions up to 3 years before anticipated entry into U.

Lipidomic and Ultrastructural Characterization of the Cell Envelope of Staphylococcus aureus Grown in the Presence of Human Serum.

can incorporate exogenous straight-chain unsaturated and saturated fatty acids (SCUFAs and SCFAs, respectively) to replace some of the normally biosynthesized branched-chain fatty acids and SCFAs. In this study, the impact of human serum on the lipidome and cell envelope structure was comprehensively characterized. When was grown in the presence of 20% human serum, typical human serum lipids, such as cholesterol, sphingomyelin, phosphatidylethanolamines, and phosphatidylcholines, were present in the total lipid extracts.

Air Ambulance and Emergency Retrieval Services in Western Australia: Caseload Analysis Over 5 Years.

Objective: The Royal Flying Doctor Service Western Operations (RFDSWO) provides critical care transfer and retrieval services across 2.5 million km to a population of 2.58 million people, providing both primary and secondary retrievals across Western Australia.

Transcriptional profiling and metabolomic analysis of Staphylococcus aureus grown on autoclaved chicken breast.

Although Staphylococcus aureus is a major cause of food poisoning, little is known about its response to growth on food. Utilizing a transcriptional profiling and metabolomics approach, we compared S. aureus grown on autoclaved chicken breast (ACB) to Luria broth agar.

Interrelationships between Fatty Acid Composition, Staphyloxanthin Content, Fluidity, and Carbon Flow in the Membrane.

Fatty acids play a major role in determining membrane biophysical properties. produces branched-chain fatty acids (BCFAs) and straight-chain saturated fatty acids (SCSFAs), and can directly incorporate exogenous SCSFAs and straight-chain unsaturated fatty acids (SCUFAs). Many strains produce the triterpenoid pigment staphyloxanthin, and the balance of BCFAs, SCSFAs and staphyloxanthin determines membrane fluidity.

Exposure of Staphylococcus aureus to Targocil Blocks Translocation of the Major Autolysin Atl across the Membrane, Resulting in a Significant Decrease in Autolysis.

Peptidoglycan (PG) and wall teichoic acid (WTA) are the major staphylococcal cell wall components, and WTA biosynthesis has recently been explored for drug development. Targocil is a novel agent that targets the TarG subunit of the WTA translocase (TarGH) that transports WTA across the membrane to the wall. Previously we showed that targocil treatment of a methicillin-susceptible strain led to a rapid shut down of cellular autolysis.

Roles of pyruvate dehydrogenase and branched-chain α-keto acid dehydrogenase in branched-chain membrane fatty acid levels and associated functions in Staphylococcus aureus.

Purpose: Membrane fluidity to a large extent is governed by the presence of branched-chain fatty acids (BCFAs). Branched-chain α-keto acid dehydrogenase (BKD) is the key enzyme in BCFA synthesis. A Staphylococcus aureus BKD-deficient strain still produced substantial levels of BCFAs.

In-Flight Pharmacological Management of Patients with Acute Mental Health Disturbance.

Objective: Patients can be transferred many hundreds of kilometers with acute mental health disturbance for specialist mental health services in Western Australia.

Methods: A retrospective notes review of Royal Flying Doctor Service Western Operations records was undertaken over a 4-month period. Patients were identified from the transfer database by mental health diagnosis.

Ethanol-induced stress response of Staphylococcus aureus.

Transcriptional profiles of 2 unrelated clinical methicillin-resistant Staphylococcus aureus (MRSA) isolates were analyzed following 10% (v/v) ethanol challenge (15 min), which arrested growth but did not reduce viability. Ethanol-induced stress (EIS) resulted in differential gene expression of 1091 genes, 600 common to both strains, of which 291 were upregulated. With the exception of the downregulation of genes involved with osmotic stress functions, EIS resulted in the upregulation of genes that contribute to stress response networks, notably those altered by oxidative stress, protein quality control in general, and heat shock in particular.

Alginate increases water stability whilst maintaining diet digestibility in farmed saltwater crocodiles ().

Saltwater crocodile () farming in Papua New Guinea is an emerging industry that supplies high-quality skins to the fashion industry. Crocodiles are semiaquatic and fed high-quality feed made from extrudated animal byproducts (i.e.

Utilization of multiple substrates by butyrate kinase from Listeria monocytogenes.

Listeria monocytogenes, the causative agent of listeriosis, can build up to dangerous levels in refrigerated foods potentially leading to expensive product recalls. An important aspect of the bacterium's growth at low temperatures is its ability to increase the branched-chain fatty acid anteiso C15:0 content of its membrane at lower growth temperatures, which imparts greater membrane fluidity. Mutants in the branched-chain α-keto dehydrogenase (bkd) complex are deficient in branched-chain fatty acids (BCFAs,) but these can be restored by feeding C4 and C5 branched-chain carboxylic acids (BCCAs).

Growth-Environment Dependent Modulation of Staphylococcus aureus Branched-Chain to Straight-Chain Fatty Acid Ratio and Incorporation of Unsaturated Fatty Acids.

The fatty acid composition of membrane glycerolipids is a major determinant of Staphylococcus aureus membrane biophysical properties that impacts key factors in cell physiology including susceptibility to membrane active antimicrobials, pathogenesis, and response to environmental stress. The fatty acids of S. aureus are considered to be a mixture of branched-chain fatty acids (BCFAs), which increase membrane fluidity, and straight-chain fatty acids (SCFAs) that decrease it.

Insights into the Mechanism of Homeoviscous Adaptation to Low Temperature in Branched-Chain Fatty Acid-Containing Bacteria through Modeling FabH Kinetics from the Foodborne Pathogen Listeria monocytogenes.

The psychrotolerant foodborne pathogen Listeria monocytogenes withstands the stress of low temperatures and can proliferate in refrigerated food. Bacteria adapt to growth at low temperatures by increasing the production of fatty acids that increase membrane fluidity. The mechanism of homeoviscous increases in unsaturated fatty acid amounts in bacteria that predominantly contain straight-chain fatty acids is relatively well understood.