Identification of emergent blaCMY-2-carrying Proteus mirabilis lineages by whole-genome sequencing

AbstractWhole-genome sequencing of 24 Proteus mirabilis isolates revealed the clonal expansion of two cefoxitin-resistant strains among patients with community-onset infection. These strains harboured blaCMY-2 within a chromosomally located integrative and conjugative element and exhibited multidrug resistance phenotypes. A predominant strain, identified in 18 patients, also harboured the PGI-1 genomic island and associated resistance genes, accounting for its broader antibiotic resistance profile. The identification of these novel multidrug-resistant strains among community-onset infections suggests that they are endemic to this region and represent emergent P. mirabilis lineages of clinical significance

Erratum to: Surface layer proteins from virulent Clostridium difficile ribotypes exhibit signatures of positive selection with consequences for innate immune response

“Upon publication of the original article [1], it was noticed that there was an error in the author name. The author’s name should be "Micheál Mac Aogáin" instead of Micheál MacAogain.

Mathematical-based microbiome analytics for clinical translation

This is the final version. Available on open access from Elsevier via the DOI in this recordTraditionally, human microbiology has been strongly built on the laboratory focused culture of microbes isolated from human specimens in patients with acute or chronic infection. These approaches primarily view human disease through the lens of a single species and its relevant clinical setting however such approaches fail to account for the surrounding environment and wide microbial diversity that exists in vivo. Given the emergence of next generation sequencing technologies and advancing bioinformatic pipelines, researchers now have unprecedented capabilities to characterise the human microbiome in terms of its taxonomy, function, antibiotic resistance and even bacteriophages. Despite this, an analysis of microbial communities has largely been restricted to ordination, ecological measures, and discriminant taxa analysis. This is predominantly due to a lack of suitable computational tools to facilitate microbiome analytics. In this review, we first evaluate the key concerns related to the inherent structure of microbiome datasets which include its compositionality and batch effects. We describe the available and emerging analytical techniques including integrative analysis, machine learning, microbial association networks, topological data analysis (TDA) and mathematical modelling. We also present how these methods may translate to clinical settings including tools for implementation. Mathematical based analytics for microbiome analysis represents a promising avenue for clinical translation across a range of acute and chronic disease states.Singapore Ministry of Health’s National Medical Research CouncilNanyang Technological University, SingaporeEngineering and Physical Sciences Research Council (EPSRC

Memory Th1 Cells Are Protective in Invasive Staphylococcus aureus Infection

Mechanisms of protective immunity to Staphylococcus aureus infection in humans remain elusive. While the importance of cellular immunity has been shown in mice, T cell responses in humans have not been characterised. Using a murine model of recurrent S. aureus peritonitis, we demonstrated that prior exposure to S. aureus enhanced IFNγ responses upon subsequent infection, while adoptive transfer of S. aureus antigen-specific Th1 cells was protective in naïve mice. Translating these findings, we found that S. aureus antigen-specific Th1 cells were also significantly expanded during human S. aureus bloodstream infection (BSI). These Th1 cells were CD45RO+, indicative of a memory phenotype. Thus, exposure to S. aureus induces memory Th1 cells in mice and humans, identifying Th1 cells as potential S. aureus vaccine targets. Consequently, we developed a model vaccine comprising staphylococcal clumping factor A, which we demonstrate to be an effective human T cell antigen, combined with the Th1-driving adjuvant CpG. This novel Th1-inducing vaccine conferred significant protection during S. aureus infection in mice. This study notably advances our understanding of S. aureus cellular immunity, and demonstrates for the first time that a correlate of S. aureus protective immunity identified in mice may be relevant in humans

Metagenomics reveals a core macrolide resistome related to microbiota in chronic respiratory disease

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordRationale: Long-term antibiotic use for managing chronic respiratory disease is increasing however the role of the airway resistome and its relationship to host microbiomes remains unknown Objective: To evaluate airway resistomes, and, relate them to host and environmental microbiomes using ultra-deep metagenomic shotgun sequencing Methods: Airway specimens from n=85 individuals with and without chronic respiratory disease (severe asthma, COPD and bronchiectasis) were subjected to metagenomic sequencing to an average depth exceeding twenty million reads. Respiratory and device-associated microbiomes were evaluated based on taxonomical classification and functional annotation including the Comprehensive Antibiotic Resistance Database (CARD) to determine airway resistomes. Co-occurrence networks of gene-microbe association were constructed to determine potential microbial sources of the airway resistome. Paired patient-inhaler metagenomes were compared (n=31) to assess for the presence of airway-environment overlap in microbiomes and/or resistomes. Results: Airway metagenomes exhibit taxonomic and metabolic diversity and distinct antimicrobial resistance patterns. A ‘core’ airway resistome dominated by macrolide but with high prevalence of β-lactam, fluoroquinolone and tetracycline resistance genes exist, and, is independent of disease status or antibiotic exposure. Streptococcus and Actinomyces are key potential microbial reservoirs of macrolide resistance including the ermX, ermF and msrD genes. Significant patient-inhaler overlap in airway microbiomes and their resistomes is identified where the latter may be a proxy for airway microbiome assessment in chronic respiratory disease. Conclusion: Metag

Sex Steroids Induce Membrane Stress Responses and Virulence Properties in Pseudomonas aeruginosa.

Estrogen, a major female sex steroid hormone, has been shown to promote the selection of mucoid Pseudomonas aeruginosa in the airways of patients with chronic respiratory diseases, including cystic fibrosis. This results in long-term persistence, poorer clinical outcomes, and limited therapeutic options. In this study, we demonstrate that at physiological concentrations, sex steroids, including testosterone and estriol, induce membrane stress responses in P. aeruginosa This is characterized by increased virulence and consequent inflammation and release of proinflammatory outer membrane vesicles promoting in vivo persistence of the bacteria. The steroid-induced P. aeruginosa response correlates with the molecular polarity of the hormones and membrane fluidic properties of the bacteria. This novel mechanism of interaction between sex steroids and P. aeruginosa explicates the reported increased disease severity observed in females with cystic fibrosis and provides evidence for the therapeutic potential of the modulation of sex steroids to achieve better clinical outcomes in patients with hormone-responsive strains.IMPORTANCE Molecular mechanisms by which sex steroids interact with P. aeruginosa to modulate its virulence have yet to be reported. Our work provides the first characterization of a steroid-induced membrane stress mechanism promoting P. aeruginosa virulence, which includes the release of proinflammatory outer membrane vesicles, resulting in inflammation, host tissue damage, and reduced bacterial clearance. We further demonstrate that at nanomolar (physiological) concentrations, male and female sex steroids promote virulence in clinical strains of P. aeruginosa based on their dynamic membrane fluidic properties. This work provides, for the first-time, mechanistic insight to better understand and predict the P. aeruginosa related response to sex steroids and explain the interindividual patient variability observed in respiratory diseases such as cystic fibrosis that are complicated by gender differences and chronic P. aeruginosa infection

Microbial Dysregulation of the Gut-Lung Axis in Bronchiectasis

This is the author accepted manuscript. The final version is available from the American Thoracic Society via the DOI in this recordIntroduction: Emerging data supports the existence of a microbial ‘gut-lung’ axis that remains unexplored in bronchiectasis. Methods: Prospective and concurrent sampling of gut (stool) and lung (sputum) was performed in a cohort of n=57 individuals with bronchiectasis and subjected to bacteriome (16S rRNA) and mycobiome (18S ITS) sequencing (total 228 microbiomes). Shotgun metagenomics was performed in a subset (n=15; 30 microbiomes). Data from gut and lung compartments were ‘integrated’ by weighted Similarity Network Fusion (wSNF), clustered and subjected to co-occurrence analysis to evaluate ‘gut-lung’ networks. Murine experiments were undertaken to validate specific Pseudomonas-driven ‘gut-lung’ interactions. Results: Microbial communities in stable bronchiectasis demonstrate significant ‘gut-lung’ interaction. Multi-biome integration followed by unsupervised clustering reveals two patient clusters, differing by ‘gut-lung’ interactions and with contrasting clinical phenotypes. A ‘high gut-lung interaction’ cluster characterized by lung Pseudomonas, gut Bacteroides and gut Saccharomyces associates with increased exacerbations, greater radiological and overall bronchiectasis severity while the ‘low gut-lung interaction’ cluster demonstrates an overrepresentation of lung commensals including Prevotella, Fusobacterium and Porphyromonas with gut Candida. The lung Pseudomonas-gut Bacteroides relationship, observed in the ‘high gut-lung interaction’ bronchiectasis cluster, was validated in a murine model of lung Pseudomonas aeruginosa (PAO1) infection. This interaction was abrogated following antibiotic (imipenem) pre-treatment in mice confirming the relevance and therapeutic potential of targeting the gut microbiome to influence the ‘gut-lung’ axis. Metagenomics in a subset of individuals with bronchiectasis corroborated our findings from targeted analyses. Conclusion: A dysregulated ‘gut-lung’ axis, driven by lung Pseudomonas, associates with poorer clinical outcomes in bronchiectasis.Engineering and Physical Sciences Research Council (EPSRC)National Medical Research Council, Singapore Ministry of HealthFondazione IRCCS Cà Grand

Geographic variation in the aetiology, epidemiology and microbiology of bronchiectasis

Bronchiectasis is a disease associated with chronic progressive and irreversible dilatation of the bronchi and is characterised by chronic infection and associated inflammation. The prevalence of bronchiectasis is age-related and there is some geographical variation in incidence, prevalence and clinical features. Most bronchiectasis is reported to be idiopathic however post-infectious aetiologies dominate across Asia especially secondary to tuberculosis. Most focus to date has been on the study of airway bacteria, both as colonisers and causes of exacerbations. Modern molecular technologies including next generation sequencing (NGS) have become invaluable tools to identify microorganisms directly from sputum and which are difficult to culture using traditional agar based methods. These have provided important insight into our understanding of emerging pathogens in the airways of people with bronchiectasis and the geographical differences that occur. The contribution of the lung microbiome, its ethnic variation, and subsequent roles in disease progression and response to therapy across geographic regions warrant further investigation. This review summarises the known geographical differences in the aetiology, epidemiology and microbiology of bronchiectasis. Further, we highlight the opportunities offered by emerging molecular technologies such as -omics to further dissect out important ethnic differences in the prognosis and management of bronchiectasis.NMRC (Natl Medical Research Council, S’pore)MOH (Min. of Health, S’pore)Published versio