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Virulent infectious agents such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and methicillin-resistant Staphylococcus aureus (MRSA) induce tissue damage that recruits neutrophils, monocyte, and macrophages, leading to T cell exhaustion, fibrosis, vascular leak, epithelial cell depletion, and fatal organ damage. Neutrophils, monocytes, and macrophages recruited to pathogen-infected lungs, including SARS-CoV-2-infected lungs, express phosphatidylinositol 3-kinase gamma (PI3Kγ), a signaling protein that coordinates both granulocyte and monocyte trafficking to diseased tissues and immune-suppressive, profibrotic transcription in myeloid cells. PI3Kγ deletion and inhibition with the clinical PI3Kγ inhibitor eganelisib promoted survival in models of infectious diseases, including SARS-CoV-2 and MRSA, by suppressing inflammation, vascular leak, organ damage, and cytokine storm. These results demonstrate essential roles for PI3Kγ in inflammatory lung disease and support the potential use of PI3Kγ inhibitors to suppress inflammation in severe infectious diseases.

UNLABELLED: Infections caused by Staphylococcus aureus are a leading cause of mortality worldwide. S. aureus infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are particularly difficult to treat due to their resistance to next-generation β-lactams (NGBs) such as methicillin, nafcillin, and oxacillin. Resistance to NGBs, which is alternatively known as broad-spectrum β-lactam resistance, is classically mediated by PBP2a, a penicillin-binding protein encoded by mecA (or mecC) in MRSA. Thus, presence of mec genes among S. aureus spp. serves as the predictor of resistance to NGBs and facilitates determination of the proper therapeutic strategy for a staphylococcal infection. Although far less appreciated, mecA-deficient S. aureus strains can also exhibit NGB resistance. These strains, which are collectively termed as methicillin-resistant lacking mec (MRLM), are currently being identified in increasing numbers among natural resistant isolates of S. aureus. The mechanism/s through which MRLMs produce resistance to NGBs remains unknown. In this study, we demonstrate that mutations that alter PBP4 and GdpP functions, which are often present among MRLMs, can synergistically mediate resistance to NGBs. Furthermore, our results unravel that this novel mechanism potentially enables MRLMs to produce resistance toward NGBs at levels comparable to those of MRSAs. Our study provides a fresh new perspective about alternative mechanisms of NGB resistance, challenging our current overall understanding of high-level, broad-spectrum β-lactam resistance in S. aureus. It thus suggests reconsideration of the current approach toward diagnosis and treatment of β-lactam-resistant S. aureus infections. IMPORTANCE: In Staphylococcus aureus, high-level, broad-spectrum resistance to β-lactams such as methicillin, also referred to as methicillin resistance, is largely attributed to mecA. This study demonstrates that S. aureus strains that lack mecA but contain mutations that functionally alter PBP4 and GdpP can also mediate high-level, broad-spectrum resistance to β-lactams. Resistance brought about by the synergistic action of functionally altered PBP4 and GdpP was phenotypically comparable to that displayed by mecA, as seen by increased bacterial survival in the presence of β-lactams. An analysis of mutations detected in naturally isolated strains of S. aureus revealed that a significant proportion of them had similar pbp4 and GGDEF domain protein containing phosphodiesterase (gdpP) mutations, making this study clinically significant. This study not only identifies important players of non-classical mechanisms of β-lactam resistance but also indicates reconsideration of current clinical diagnosis and treatment protocols of S. aureus infections.

Host-directed therapy (HDT) is an emerging approach to overcome antimicrobial resistance in pathogenic microorganisms. Specifically, HDT targets host-encoded factors required for pathogen replication and survival without interfering with microbial growth or metabolism, thereby eliminating the risk of resistance development. By applying HDT and a drug repurposing approach, we demonstrate that (R)-DI-87, a clinical-stage anticancer drug and potent inhibitor of mammalian deoxycytidine kinase (dCK), mitigates Staphylococcus aureus abscess formation in organ tissues upon invasive bloodstream infection. Mechanistically, (R)-DI-87 shields phagocytes from staphylococcal death-effector deoxyribonucleosides that target dCK and the mammalian purine salvage pathway-apoptosis axis. In this manner, (R)-DI-87-mediated protection of immune cells amplifies macrophage infiltration into deep-seated abscesses, a phenomenon coupled with enhanced pathogen control, ameliorated immunopathology, and reduced disease severity. Thus, pharmaceutical blockade of dCK represents an advanced anti-infective intervention strategy against which staphylococci cannot develop resistance and may help to fight fatal infectious diseases in hospitalized patients.

BACKGROUND: Community-acquired Staphylococcus aureus (CA-Sa) skin and soft tissue infections (SSTIs) are historically associated with densely populated urban areas experiencing high poverty rates, intravenous drug use, and homelessness. However, the epidemiology of CA-Sa SSTIs in the United States has been poorly understood since the plateau of the Community-acquired Methicillin-resistant Staphylococcus aureus epidemic in 2010. This study examines the spatial variation of CA-Sa SSTIs in a large, geographically heterogeneous population and identifies neighborhood characteristics associated with increased infection risk. METHODS: Using a unique neighborhood boundary, California Medical Service Study Areas, a hotspot analysis, and estimates of neighborhood infection risk ratios were conducted for all CA-Sa SSTIs presented in non-Federal California emergency departments between 2016 and 2019. A Bayesian Poisson regression model evaluated the association between neighborhood-level infection risk and population structure, neighborhood poverty rates, and being a healthcare shortage area. RESULTS: Emergency departments in more rural and mountainous parts of California experienced a higher burden of CA-Sa SSTIs between 2016 and 2019. Neighborhoods with high infection rates were more likely to have a high percentage of adults living below the federal poverty level and be a designated healthcare shortage area. Measures of population structure were not associated with infection risk in California neighborhoods. CONCLUSIONS: Our results highlight a potential change in the epidemiology of CA-Sa SSTIs in California emergency departments. Future studies should investigate the CA-Sa burden in other geographies to identify whether this shift in epidemiology holds across other states and populations. Further, a more thorough evaluation of potential mechanisms for the clustering of infections seen across California neighborhoods is needed.

Methicillin-resistant Staphylococcus aureus (MRSA) is an important zoonotic pathogen associated with a wide range of infections in humans and animals. Thus, the emergence of MRSA clones poses an important threat to human and animal health. This study is aimed at elucidating the genomics insights of a strong biofilm-producing and multidrug-resistant (MDR) S. aureus MTR_BAU_H1 strain through whole-genome sequencing (WGS). The S. aureus MTR_BAU_H1 strain was isolated from food handlers hand swabs in Bangladesh and phenotypically assessed for antimicrobial susceptibility and biofilm production assays. The isolate was further undergone to high throughput WGS and analysed using different bioinformatics tools to elucidate the genetic diversity, molecular epidemiology, sequence type (ST), antimicrobial resistance, and virulence gene distribution. Phenotypic analyses revealed that the S. aureus MTR_BAU_H1 strain is a strong biofilm-former and carries both antimicrobial resistance (e.g., methicillin resistance; mecA, beta-lactam resistance; blaZ and tetracycline resistance; tetC) and virulence (e.g., sea, tsst, and PVL) genes. The genome of the S. aureus MTR_BAU_H1 belonged to ST1930 that possessed three plasmid replicons (e.g., rep16, rep7c, and rep19), seven prophages, and two clustered regularly interspaced short palindromic repeat (CRISPR) arrays of varying sizes. Phylogenetic analysis showed a close evolutionary relationship between the MTR_BAU_H1 genome and other MRSA clones of diverse hosts and demographics. The MTR_BAU_H1 genome harbours 42 antimicrobial resistance genes (ARGs), 128 virulence genes, and 273 SEED subsystems coding for the metabolism of amino acids, carbohydrates, proteins, cofactors, vitamins, minerals, and lipids. This is the first-ever WGS-based study of a strong biofilm-producing and MDR S. aureus strain isolated from human hand swabs in Bangladesh that unveils new information on the resistomes (ARGs and correlated mechanisms) and virulence potentials that might be linked to staphylococcal pathogenesis in both humans and animals.

INTRODUCTION: Staphylococcus aureus bacteremia (SAB) is a life-threatening infection particularly involving methicillin-resistant S. aureus (MRSA). In contrast to resolving MRSA bacteremia (RB), persistent MRSA bacteremia (PB) blood cultures remain positive despite appropriate antibiotic treatment. Host immune responses distinguishing PB vs. RB outcomes are poorly understood. Here, integrated transcriptomic, IL-10 cytokine levels, and genomic analyses sought to identify signatures differentiating PB vs. RB outcomes. METHODS: Whole-blood transcriptomes of propensity-matched PB (n=28) versus RB (n=30) patients treated with vancomycin were compared in one independent training patient cohort. Gene expression (GE) modules were analyzed and prioritized relative to host IL-10 cytokine levels and DNA methyltransferase-3A (DNMT3A) genotype. RESULTS: Differential expression of T and B lymphocyte gene expression early in MRSA bacteremia discriminated RB from PB outcomes. Significant increases in effector T and B cell signaling pathways correlated with RB, lower IL-10 cytokine levels and DNMT3A heterozygous A/C genotype. Importantly, a second PB and RB patient cohort analyzed in a masked manner demonstrated high predictive accuracy of differential signatures. DISCUSSION: Collectively, the present findings indicate that human PB involves dysregulated immunity characterized by impaired T and B cell responses associated with excessive IL-10 expression in context of the DNMT3A A/A genotype. These findings reveal distinct immunologic programs in PB vs. RB outcomes, enable future studies to define mechanisms by which host and/or pathogen drive differential signatures and may accelerate prediction of PB outcomes. Such prognostic assessment of host risk could significantly enhance early anti-infective interventions to avert PB and improve patient outcomes.

Brodies abscess is a manifestation of subacute to chronic osteomyelitis, characterized as intraosseous abscess formation, usually on the metaphysis of the long tubular bones in the lower extremities of male pediatric patients. Clinically, Brodies abscess presents with atraumatic bone pain of an insidious onset, with absence of systemic findings. Delay in diagnosis is common, as diagnostic imaging, followed by biopsy for culture and histologic examination are generally required to secure a diagnosis of Brodies abscess. Treatment of Brodies abscess is non-standardized, and usually consists of surgical debridement and antibacterial therapy. Despite the variability in therapeutic approaches, outcomes of Brodies abscess treated with surgery and antibiotics are favourable. Herein we report a case of a delayed diagnosis of Brodies abscess in the upper extremity of an adult female. While she improved with treatment of Brodies abscess, the case serves to remind clinicians to consider this entity in adult individuals who present with atraumatic bone pain.

The Staphylococcus aureus Network Adaptive Platform (SNAP) trial is a multifactorial Bayesian adaptive platform trial that aims to improve the way that S. aureus bloodstream infection, a globally common and severe infectious disease, is treated. In a world first, the SNAP trial will simultaneously investigate the effects of multiple intervention modalities within multiple groups of participants with different forms of S. aureus bloodstream infection. Here, we formalise the trial structure, modelling approach, and decision rules that will be used for the SNAP trial. By summarising the statistical principles governing the design, our hope is that the SNAP trial will serve as an adaptable template that can be used to improve comparative effectiveness research efficiency in other disease areas.Trial registration NCT05137119 . Registered on 30 November 2021.

OBJECTIVE: To determine the antimicrobial resistance pattern in Linezolid-resistant coagulase negative staphylococcus (CoNS) isolates in Pakistan. METHODS: This cross-sectional study was conducted from February and July 2022, at a private laboratory in Lahore, with samples collected from various regions across Pakistan. The study included microbiological samples such as blood and wound specimens, from which 4,153 isolates of CoNS were identified. Of these, only 64 isolates that were both coagulase-negative and Linezolid-resistant were selected for further investigation. The antimicrobial susceptibility patterns of these Linezolid-resistant isolates were analyzed. The antibiotics tested included amikacin, ciprofloxacin, clindamycin, doxycycline, erythromycin, fusidic acid, gentamicin, oxacillin, teicoplanin, trimethoprim-sulfamethoxazole, and vancomycin. Data analysis was performed using SPSS version-22. RESULTS: Among 4153 samples, 64 (1.54%) were Linezolid-resistant CoNS isolates, predominantly from adults (aging 18-59 years) and senior adults (aging >59 years), with a higher prevalence in males (56.3%). Resistance was observed in 51.6% of blood and 48.4% of pus samples. Most isolates were also resistant to teicoplanin (100%), ciprofloxacin (92.2%), oxacillin (89.1%), and fusidic acid (84.4%), while sensitivity was highest for vancomycin (85.9%) and doxycycline (79.7%). Statistically significant differences were noted for all antibiotics except erythromycin. CONCLUSION: Our findings highlight the importance of monitoring the evolution of Linezolid resistance in CoNS as Linezolid resistant isolates also showed high resistance to some other major antimicrobial drugs (e.g. teicoplanin, ciprofloxacin, oxacillin etc.). Linezolid resistance must be closely monitored, especially when frequent and prolonged Linezolid therapy is indicated to implement control measures and reduce the risk of CoNS spreading in the community.

Infection caused by Staphylococcus aureus is the most common infection leading to the development of serious complications in humans. S. aureus is among the highly lethal bacteremia-associated pathogens with a mortality rate of approximately 18% in industrial countries; in developing countries, the rate is even higher, up to 27%. One of the most striking and challenging aspects of clinical manifestations caused by S. aureus is the ability of the bacterium to develop resistance to antibiotics. The development of alternative treatment options for staphylococcal infection is urgently needed. The use of immunotherapy and immunoprophylaxis to activate the anti-infection immune response in patients should be considered as a promising direction. Objective: to analyze the main trends in the development of vaccines aimed at the prevention of S. aureus infection and its virulence factors. The present review discusses vaccine development in recent years aimed at preventing infection caused by S. aureus. Particular attention is paid to pathogenicity factors (such as capsule, surface proteins and enzymes) that may be useful for the development of new candidate vaccines or immune therapeutics. In recent years, numerous clinical trials of candidate vaccines based on different antigens, taking into account particularly relevant S. aureus pathogenicity factors that influence morbidity, have not been successful due to their low efficacy or insufficiently substantiated safety (development of adverse events). One of the most important factors constraining vaccine development is the lack of successful translation of vaccine protective activity, which is observed in preclinical studies in experimental models but not confirmed in clinical trials. Therefore, according to numerous researchers, the use of multiple antigens in vaccine formulations should be considered with the focus on different mechanisms of S. aureus pathogenicity and the use of adjuvants.

ImportanceUniversal nasal mupirocin plus chlorhexidine gluconate (CHG) bathing in intensive care units (ICUs) prevents methicillin-resistant Staphylococcus aureus (MRSA) infections and all-cause bloodstream infections. Antibiotic resistance to mupirocin has raised questions about whether an antiseptic could be advantageous for ICU decolonization.ObjectiveTo compare the effectiveness of iodophor vs mupirocin for universal ICU nasal decolonization in combination with CHG bathing.Design, setting, and participantsTwo-group noninferiority, pragmatic, cluster-randomized trial conducted in US community hospitals, all of which used mupirocin-CHG for universal decolonization in ICUs at baseline. Adult ICU patients in 137 randomized hospitals during baseline (May 1, 2015-April 30, 2017) and intervention (November 1, 2017-April 30, 2019) were included.InterventionUniversal decolonization involving switching to iodophor-CHG (intervention) or continuing mupirocin-CHG (baseline).Main outcomes and measuresICU-attributable S aureus clinical cultures (primary outcome), MRSA clinical cultures, and all-cause bloodstream infections were evaluated using proportional hazard models to assess differences from baseline to intervention periods between the strategies. Results were also compared with a 2009-2011 trial of mupirocin-CHG vs no decolonization in the same hospital network. The prespecified noninferiority margin for the primary outcome was 10%.ResultsAmong the 801 668 admissions in 233 ICUs, the participants' mean (SD) age was 63.4 (17.2) years, 46.3% were female, and the mean (SD) ICU length of stay was 4.8 (4.7) days. Hazard ratios (HRs) for S aureus clinical isolates in the intervention vs baseline periods were 1.17 for iodophor-CHG (raw rate: 5.0 vs 4.3/1000 ICU-attributable days) and 0.99 for mupirocin-CHG (raw rate: 4.1 vs 4.0/1000 ICU-attributable days) (HR difference in differences significantly lower by 18.4% [95% CI, 10.7%-26.6%] for mupirocin-CHG, P

BackgroundVertebral discitis-osteomyelitis (VDO) is a devastating infection of the spine that is challenging to distinguish from noninfectious mimics using computed tomography and magnetic resonance imaging. We and others have developed novel metabolism-targeted positron emission tomography (PET) radiotracers for detecting living Staphylococcus aureus and other bacteria in vivo, but their head-to-head performance in a well-validated VDO animal model has not been reported.MethodsWe compared the performance of several PET radiotracers in a rat model of VDO. [11C]PABA and [18F]FDS were assessed for their ability to distinguish S aureus, the most common non-tuberculous pathogen VDO, from Escherichia coli.ResultsIn the rat S aureus VDO model, [11C]PABA could detect as few as 103 bacteria and exhibited the highest signal-to-background ratio, with a 20-fold increased signal in VDO compared to uninfected tissues. In a proof-of-concept experiment, detection of bacterial infection and discrimination between S aureus and E coli was possible using a combination of [11C]PABA and [18F]FDS.ConclusionsOur work reveals that several bacteria-targeted PET radiotracers had sufficient signal to background in a rat model of S aureus VDO to be potentially clinically useful. [11C]PABA was the most promising tracer investigated and warrants further investigation in human VDO.

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of morbidity and mortality. Colonization by MRSA increases the risk of infection and transmission, underscoring the importance of decolonization efforts. However, success of these decolonization protocols varies, raising the possibility that some MRSA strains may be more persistent than others. Here, we studied how the persistence of MRSA colonization correlates with genomic presence of antibiotic resistance genes. Our analysis using a Bayesian mixed effects survival model found that genetic determinants of high-level resistance to mupirocin was strongly associated with failure of the decolonization protocol. However, we did not see a similar effect with genetic resistance to chlorhexidine or other antibiotics. Including strain-specific random effects improved the predictive performance, indicating that some strain characteristics other than resistance also contributed to persistence. Study subject-specific random effects did not improve the model. Our results highlight the need to consider the properties of the colonizing MRSA strain when deciding which treatments to include in the decolonization protocol.

BACKGROUND: Hispanic people with CF (pwCF) have increased morbidity than non-Hispanic White pwCF, including increased risk of Pseudomonas aeruginosa. We aimed to determine if Staphylococcus aureus (S. aureus) acquisition varies between Hispanic and non-Hispanic White pwCF. METHODS: This longitudinal cohort study of pwCF ages 0-25 years in the CF Foundation Patient Registry compared acquisition of methicillin-sensitive S. aureus (MSSA), methicillin-resistant S. aureus (MRSA), persistent MRSA between Hispanic and non-Hispanic White pwCF. Risk of acquisition was assessed by Kaplan-Meier survival curves and its association with ethnicity was evaluated using Cox regressions. Adjusted associations were evaluated using multivariate Cox models adjusting for sex, age of entry into CFFPR, CFTR variant severity, pancreatic insufficiency, CF-related diabetes, maternal education, insurance status. RESULTS: Of 10,640 pwCF, 7.5% were Hispanic and 92.5% were non-Hispanic White. Hispanic pwCF had a 19% higher risk of acquiring MSSA (HR 1.19, 95% CI 1.10-1.28, p

Staphylococcus epidermidis is a common microbe on human skin and has beneficial functions in the skin microbiome. However, under conditions of allergic inflammation, the abundance of S. epidermidis increases, establishing potential danger to the epidermis. To understand how this commensal may injure the host, we investigate phenol-soluble modulin (PSM) peptides produced by S. epidermidis that are similar to peptides produced by Staphylococcus aureus. Synthetic S. epidermidis PSMs induce expression of host defense genes and are cytotoxic to human keratinocytes. Deletion mutants of S. epidermidis lacking these gene products support these observations and further show that PSMs require the action of the EcpA bacterial protease to induce inflammation when applied on mouse skin with an intact stratum corneum. The expression of PSMδ from S. epidermidis is also found to correlate with disease severity in patients with atopic dermatitis. These observations show how S. epidermidis PSMs can promote skin inflammation.

Aim of study. The current rate of increase in the number of antimicrobial-resistant infections is poised to become the leading global cause of loss of human life. The limited discovery of new antibiotics necessitates investment in alternative solutions. Bacteriophages, viruses that target bacteria, offer a potent alternative approach to combating bacterial infections. One area of modern microbiology and biotechnology that has garnered significant interest is the study of bacteriophages, owing to their potential practical application in various branches of medicine. Material and methods. This study conducted a comprehensive synthesis of specialized reference sources from international open-access databases, examining the impact of bacteriophage therapy on staphylococcal infections and antimicrobial resistance. Results. The synthesis is based on studies in human clinical trials, including randomized clinical trials, based on data from recent years. Multiple successful cases regarding the use of phages in the treatment of human infections have been reported. The studies conducted provide evidence that the development of phage therapy is a promising alternative for combating bacterial resistance to antibiotics. The effective action of antistaphylococcal phage cocktails against the most common strains has been demonstrated. The mechanisms underlying the phage-antibiotic synergy effect, as well as the advantages of bacteriophages over other forms of treatment, are presented. Conclusions. Therapy methods using bacteriophages in combination with antibacterial drugs can provide a higher therapeutic effect.

Antimicrobial resistance has emerged as a global public health threat, and development of novel therapeutics for treating infections caused by multi-drug resistant bacteria is urgent. Staphylococcus aureus is a major human and animal pathogen, responsible for high levels of morbidity and mortality worldwide. The intracellular survival of S. aureus in macrophages contributes to immune evasion, dissemination, and resilience to antibiotic treatment. Here, we present a confocal fluorescence imaging assay for monitoring macrophage infection by green fluorescent protein (GFP)-tagged S. aureus as a front-line tool to identify antibiotic leads. The assay was employed in combination with nanoscaled chemical analyses to facilitate the discovery of a new, active rifamycin analogue. Our findings indicate a promising new approach for the identification of antimicrobial compounds with macrophage intracellular activity. The antibiotic identified here may represent a useful addition to our armory in tackling the silent pandemic of antimicrobial resistance.

Biofilm-associated infections lead to substantial morbidity. Omadacycline (OMC) is a novel aminomethylcycline with potent in vitro activity against Staphylococcus aureus and Staphylococcus epidermidis, but data surrounding its use in biofilm-associated infections are lacking. We investigated the activity of OMC alone and in combination with rifampin (RIF) against 20 clinical strains of staphylococci in multiple in vitro biofilm analyses, including an in vitro pharmacokinetic/pharmacodynamic (PK/PD) CDC biofilm reactor (CBR) model (simulating human exposures). The observed MICs for OMC demonstrated potent activity against the evaluated strains (0.125 to 1 mg/L), with an increase of MICs generally observed in the presence of biofilm (0.25 to >64 mg/L). Furthermore, RIF was shown to reduce OMC biofilm MICs (bMICs) in 90% of strains, and OMC plus RIF combination in biofilm time-kill analyses (TKAs) exhibited synergistic activity in most of the strains. Within the PK/PD CBR model, OMC monotherapy primarily displayed bacteriostatic activity, while RIF monotherapy generally exhibited initial bacterial eradication, followed by rapid regrowth likely due to the emergence of RIF resistance (RIF bMIC, >64 mg/L). However, the combination of OMC plus RIF produced rapid and sustained bactericidal activity in nearly all the strains (3.76 to 4.03 log10 CFU/cm2 reductions from starting inoculum in strains in which bactericidal activity was reached). Furthermore, OMC was shown to prevent the emergence of RIF resistance. Our data provide preliminary evidence that OMC in combination with RIF could be a viable option for biofilm-associated infections with S. aureus and S. epidermidis. Further research involving OMC in biofilm-associated infections is warranted.

Objective: Analyse the incidence, risk factors, antimicrobial susceptibility profile, and fatality in neonates infected with oxacillin-resistant Staphylococcus spp. (ORS). Methods: In this retrospective observational descriptive cohort study, the medical records of neonates admitted to the Neonatal Intensive Care Unit (NICU) from January 2015 to June 2022 were analysed. Participants were monitored daily through the National Healthcare Safety Network. Results: Among the 1610 neonates, 193 (12 %) developed ORS infections, primarily in the bloodstream (96.8 %). The incidence of these infections/patient-days decreased by 51.8 % between 2016 (8.3) and 2022 (4). The median age of affected neonates was 17.5 days (IQR:12–28.7). Pre-emptive prescription of fourth-generation cephalosporins (OR=14.36; P