Sex-dependent gastrointestinal colonization resistance to MRSA is microbiota and Th17 dependent.

Gastrointestinal (GI) colonization by methicillin-resistant (MRSA) is associated with a high risk of transmission and invasive disease in vulnerable populations. The immune and microbial factors that permit GI colonization remain unknown. Male sex is correlated with enhanced nasal carriage, skin and soft tissue infections, and bacterial sepsis.

Interleukin 10 drives Staphylococcus aureus imprinting and vaccine failure in murine models via antibody glycosylation.

Despite many attempts, there is currently no approved vaccine to prevent Staphylococcus aureus infections. Preclinical vaccination models have failed to predict vaccine efficacy in humans as S. aureus exposure in humans imprints an immune response that is lacking in naive animals.

Histone H1 kills MRSA.

The antimicrobial activity of histones was discovered in the 1940s, but their mechanism of action is not fully known. Here we show that methicillin-resistant Staphylococcus aureus (MRSA) is susceptible to histone H1 (H1), even in the presence of divalent cations and serum. Through selective evolution and a genome-wide screen of a transposon library, as well as physiological and pharmacological experiments, we elucidated how H1 kills MRSA.

Dietary and water restriction leads to increased susceptibility to antimicrobial resistant pathogens.

Dehydration and malnutrition are common and often underdiagnosed in hospital settings. Multidrug-resistant bacterial infections result in more than 35,000 deaths a year in nosocomial patients. The effect of temporal dietary and water restriction (DWR) on susceptibility to multidrug-resistant pathogens is unknown.

Proton-coupled transport mechanism of the efflux pump NorA.

Efflux pump antiporters confer drug resistance to bacteria by coupling proton import with the expulsion of antibiotics from the cytoplasm. Despite efforts there remains a lack of understanding as to how acid/base chemistry drives drug efflux. Here, we uncover the proton-coupling mechanism of the Staphylococcus aureus efflux pump NorA by elucidating structures in various protonation states of two essential acidic residues using cryo-EM.

Microbiota and metabolic adaptation shape virulence and antimicrobial resistance during intestinal colonization.

Depletion of microbiota increases susceptibility to gastrointestinal colonization and subsequent infection by opportunistic pathogens such as methicillin-resistant (MRSA). How the absence of gut microbiota impacts the evolution of MRSA is unknown. The present report used germ-free mice to investigate the evolutionary dynamics of MRSA in the absence of gut microbiota.

Quorum-sensing system of primes gene expression for protection from lethal oxidative stress.

The quorum-sensing system links metabolism to virulence, in part by increasing bacterial survival during exposure to lethal concentrations of HO, a crucial host defense against . We now report that protection by surprisingly extends beyond post-exponential growth to the exit from stationary phase when the system is no longer turned on. Thus, can be considered a constitutive protective factor.

Prophage-encoded methyltransferase drives adaptation of community-acquired methicillin-resistant .

We recently described the evolution of a community-acquired methicillin-resistant (CA-MRSA) USA300 variant responsible for an outbreak of skin and soft tissue infections. Acquisition of a mosaic version of the Φ11 prophage (mΦ11) that increases skin abscess size was an early step in CA-MRSA adaptation that primed the successful spread of the clone. The present report shows how prophage mΦ11 exerts its effect on virulence for skin infection without encoding a known toxin or fitness genes.

Transcription-replication interactions reveal bacterial genome regulation.

Organisms determine the transcription rates of thousands of genes through a few modes of regulation that recur across the genome. In bacteria, the relationship between the regulatory architecture of a gene and its expression is well understood for individual model gene circuits. However, a broader perspective of these dynamics at the genome scale is lacking, in part because bacterial transcriptomics has hitherto captured only a static snapshot of expression averaged across millions of cells.

senses human neutrophils via PerR to coordinate the expression of the toxin LukAB.

is a gram-positive pathogen that poses a major health concern, in part due to its large array of virulence factors that allow infection and evasion of the immune system. One of these virulence factors is the bicomponent pore-forming leukocidin LukAB. The regulation of expression is not completely understood, especially in the presence of immune cells such as human polymorphonuclear neutrophils (hPMNs).

TLR4 sensing of IsdB of induces a proinflammatory cytokine response via the NLRP3-caspase-1 inflammasome cascade.

The prevalence of multidrug-resistant is of global concern, and vaccines are urgently needed. The iron-regulated surface determinant protein B (IsdB) of was investigated as a vaccine candidate because of its essential role in bacterial iron acquisition but failed in clinical trials despite strong immunogenicity. Here, we reveal an unexpected second function for IsdB in pathogen-host interaction: the bacterial fitness factor IsdB triggers a strong inflammatory response in innate immune cells via Toll-like receptor 4 and the inflammasome, thus acting as a novel pathogen-associated molecular pattern of .

Unlatching of the stem domains in the Staphylococcus aureus pore-forming leukocidin LukAB influences toxin oligomerization.

Staphylococcus aureus (S. aureus) is a serious global pathogen that causes a diverse range of invasive diseases. S.

Characterization of tigurilysin, a novel human CD59-specific cholesterol-dependent cytolysin, reveals a role for host specificity in augmenting toxin activity.

Cholesterol-dependent cytolysins (CDCs) are a large family of pore-forming toxins, produced by numerous Gram-positive pathogens. CDCs depend on host membrane cholesterol for pore formation; some CDCs also require surface-associated human CD59 (hCD59) for binding, conferring specificity for human cells. We purified a recombinant version of a putative CDC encoded in the genome of subsp, tigurilysin (TGY), and used CRISPR/Cas9 to construct hCD59 knockout (KO) HeLa and JEG-3 cell lines.

Antimicrobial overproduction sustains intestinal inflammation by inhibiting Enterococcus colonization.

Loss of antimicrobial proteins such as REG3 family members compromises the integrity of the intestinal barrier. Here, we demonstrate that overproduction of REG3 proteins can also be detrimental by reducing a protective species in the microbiota. Patients with inflammatory bowel disease (IBD) experiencing flares displayed heightened levels of secreted REG3 proteins that mediated depletion of Enterococcus faecium (Efm) from the gut microbiota.

Characterization of Tigurilysin, a Novel Human CD59-Specific Cholesterol-Dependent Cytolysin, Reveals a Role for Host Specificity in Augmenting Toxin Activity.

Unlabelled: Cholesterol dependent cytolysins (CDCs) are a large family of pore forming toxins, produced by numerous gram-positive pathogens. CDCs depend on host membrane cholesterol for pore formation; some CDCs also require surface associated human CD59 (hCD59) for binding, conferring specificity for human cells. We purified a recombinant version of a putative CDC encoded in the genome of , tigurilysin (TGY), and used CRISPR/Cas9 to construct hCD59 knockout (KO) HeLa and JEG-3 cell lines.

Single-Cell Analysis of CX3CR1+ Cells Reveals a Pathogenic Role for BIRC5+ Myeloid Proliferating Cells Driven by Staphylococcus aureus Leukotoxins.

Our previous studies identified a population of stem cell-like proliferating myeloid cells within inflamed tissues that could serve as a reservoir for tissue macrophages to adopt different activation states depending on the microenvironment. By lineage-tracing cells derived from CX3CR1+ precursors in mice during infection and profiling by single-cell RNA sequencing, in this study, we identify a cluster of BIRC5+ myeloid cells that expanded in the liver during chronic infection with either the parasite Schistosoma mansoni or the bacterial pathogen Staphylococcus aureus. In the absence of tissue-damaging toxins, S.

Rewilding of laboratory mice enhances granulopoiesis and immunity through intestinal fungal colonization.

The paucity of blood granulocyte populations such as neutrophils in laboratory mice is a notable difference between this model organism and humans, but the cause of this species-specific difference is unclear. We previously demonstrated that laboratory mice released into a seminatural environment, referred to as rewilding, display an increase in blood granulocytes that is associated with expansion of fungi in the gut microbiota. Here, we find that tonic signals from fungal colonization induce sustained granulopoiesis through a mechanism distinct from emergency granulopoiesis, leading to a prolonged expansion of circulating neutrophils that promotes immunity.

Endothelial ACKR1 is induced by neutrophil contact and down-regulated by secretion in extracellular vesicles.

Atypical chemokine receptor-1 (ACKR1), previously known as the Duffy antigen receptor for chemokines, is a widely conserved cell surface protein that is expressed on erythrocytes and the endothelium of post-capillary venules. In addition to being the receptor for the parasite causing malaria, ACKR1 has been postulated to regulate innate immunity by displaying and trafficking chemokines. Intriguingly, a common mutation in its promoter leads to loss of the erythrocyte protein but leaves endothelial expression unaffected.

Transcription-replication interactions reveal principles of bacterial genome regulation.

Organisms determine the transcription rates of thousands of genes through a few modes of regulation that recur across the genome. These modes interact with a changing cellular environment to yield highly dynamic expression patterns. In bacteria, the relationship between a gene's regulatory architecture and its expression is well understood for individual model gene circuits.