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Journal articleFillol-Salom A, Alsaadi A, de Sousa JAM, et al., 2019,
Bacteriophages benefit from generalized transduction
, PLoS Pathogens, Vol: 15, ISSN: 1553-7366Temperate phages are bacterial viruses that as part of their life cycle reside in the bacterial genome as prophages. They are found in many species including most clinical strains of the human pathogens, Staphylococcus aureus and Salmonella enterica serovar Typhimurium. Previously, temperate phages were considered as only bacterial predators, but mounting evidence point to both antagonistic and mutualistic interactions with for example some temperate phages contributing to virulence by encoding virulence factors. Here we show that generalized transduction, one type of bacterial DNA transfer by phages, can create conditions where not only the recipient host but also the transducing phage benefit. With antibiotic resistance as a model trait we used individual-based models and experimental approaches to show that antibiotic susceptible cells become resistant to both antibiotics and phage by i) integrating the generalized transducing temperate phages and ii) acquiring transducing phage particles carrying antibiotic resistance genes obtained from resistant cells in the environment. This is not observed for non-generalized transducing temperate phages, which are unable to package bacterial DNA, nor for generalized transducing virulent phages that do not form lysogens. Once established, the lysogenic host and the prophage benefit from the existence of transducing particles that can shuffle bacterial genes between lysogens and for example disseminate resistance to antibiotics, a trait not encoded by the phage. This facilitates bacterial survival and leads to phage population growth. We propose that generalized transduction can function as a mutualistic trait where temperate phages cooperate with their hosts to survive in rapidly-changing environments. This implies that generalized transduction is not just an error in DNA packaging but is selected for by phages to ensure their survival.
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Journal articleSchuster CF, Wiedemann DM, Kirsebom FCM, et al., 2019,
High-throughput transposon sequencing highlights the cell wall as an important barrier for osmotic stress in methicillin resistant<i>Staphylococcus aureus</i>and underlines a tailored response to different osmotic stressors
<jats:title>Summary</jats:title><jats:p><jats:italic>Staphylococcus aureus</jats:italic>is an opportunistic pathogen that can cause soft tissue infections but is also a frequent cause of foodborne illnesses. One contributing factor for this food association is its high salt tolerance allowing this organism to survive commonly used food preservation methods. How this resistance is mediated is poorly understood, particularly during long-term exposure. In this study, we used TN-seq to understand how the responses to osmotic stressors differ. Our results revealed distinctly different long-term responses to NaCl, KCl and sucrose stresses. In addition, we identified the DUF2538 domain containing gene<jats:italic>SAUSA300_0957</jats:italic>(gene<jats:italic>957</jats:italic>) as essential under salt stress. Interestingly, a<jats:italic>957</jats:italic>mutant was less susceptible to oxacillin and showed increased peptidoglycan crosslinking. The salt sensitivity phenotype could be suppressed by amino acid substitutions in the transglycosylase domain of the penicillin binding protein Pbp2, and these changes restored the peptidoglycan crosslinking to WT levels. These results indicate that increased crosslinking of the peptidoglycan polymer can be detrimental and highlight a critical role of the bacterial cell wall for osmotic stress resistance. This study will serve as a starting point for future research on osmotic stress response and help develop better strategies to tackle foodborne staphylococcal infections.</jats:p>
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Journal articleFisch D, Bando H, Clough B, et al., 2019,
Human GBP1 is a microbe-specific gatekeeper of macrophage apoptosis and pyroptosis
, EMBO Journal, Vol: 38, ISSN: 0261-4189The guanylate binding protein (GBP) family of interferon-inducible GTPases promotes antimicrobial immunity and cell death. During bacterial infection, multiple mouse Gbps, human GBP2, and GBP5 support the activation of caspase-1-containing inflammasome complexes or caspase-4 which trigger pyroptosis. Whether GBPs regulate other forms of cell death is not known. The apicomplexan parasite Toxoplasma gondii causes macrophage death through unidentified mechanisms. Here we report that Toxoplasma-induced death of human macrophages requires GBP1 and its ability to target Toxoplasma parasitophorous vacuoles through its GTPase activity and prenylation. Mechanistically, GBP1 promoted Toxoplasma detection by AIM2, which induced GSDMD-independent, ASC-, and caspase-8-dependent apoptosis. Identical molecular determinants targeted GBP1 to Salmonella-containing vacuoles. GBP1 facilitated caspase-4 recruitment to Salmonella leading to its enhanced activation and pyroptosis. Notably, GBP1 could be bypassed by the delivery of Toxoplasma DNA or bacterial LPS into the cytosol, pointing to its role in liberating microbial molecules. GBP1 thus acts as a gatekeeper of cell death pathways, which respond specifically to infecting microbes. Our findings expand the immune roles of human GBPs in regulating not only pyroptosis, but also apoptosis.
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Journal articleEdwards AM, 2019,
Silence is golden for <i>Staphylococcus</i>
, NATURE MICROBIOLOGY, Vol: 4, Pages: 1073-1074, ISSN: 2058-5276 -
Journal articleBalaban NQ, Helaine S, Lewis K, et al., 2019,
Definitions and guidelines for research on antibiotic persistence
, Nature Reviews Microbiology, Vol: 17, Pages: 441-448, ISSN: 1740-1526Increasing concerns about the rising rates of antibiotic therapy failure and advances in single-cell analyses have inspired a surge of research into antibiotic persistence. Bacterial persister cells represent a subpopulation of cells that can survive intensive antibiotic treatment without being resistant. Several approaches have emerged to define and measure persistence, and it is now time to agree on the basic definition of persistence and its relation to the other mechanisms by which bacteria survive exposure to bactericidal antibiotic treatments, such as antibiotic resistance, heteroresistance or tolerance. In this Consensus Statement, we provide definitions of persistence phenomena, distinguish between triggered and spontaneous persistence and provide a guide to measuring persistence. Antibiotic persistence is not only an interesting example of non-genetic single-cell heterogeneity, it may also have a role in the failure of antibiotic treatments. Therefore, it is our hope that the guidelines outlined in this article will pave the way for better characterization of antibiotic persistence and for understanding its relevance to clinical outcomes.
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Journal articleBalaban NQ, Helaine S, Lewis K, et al., 2019,
Definitions and guidelines for research on antibiotic persistence (vol 17, pg 441, 2019)
, NATURE REVIEWS MICROBIOLOGY, Vol: 17, Pages: 460-460, ISSN: 1740-1526- Author Web Link
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Journal articleAsai M, Li Y, Khara J, et al., 2019,
Use of the invertebrate Galleria Mellonella as an infection model to study the Mycobacterium tuberculosis complex
, Jove-Journal of Visualized Experiments, Vol: 148, ISSN: 1940-087XTuberculosis is the leading global cause of infectious disease mortality and roughly a quarter of the world’s population is believed to be infected with Mycobacterium tuberculosis. Despite decades of research, many of the mechanisms behind the success of M. tuberculosis as a pathogenic organism remain to be investigated, and the development of safer, more effective antimycobacterial drugs are urgently needed to tackle the rise and spread of drug resistant tuberculosis. However, the progression of tuberculosis research is bottlenecked by traditional mammalian infection models that are expensive, time consuming, and ethically challenging.Previously we established the larvae of the insect Galleria mellonella (greater wax moth) as a novel, reproducible, low cost, high-throughput and ethically acceptable infection model for members of the M. tuberculosis complex. Here we describe the maintenance, preparation, and infection of G. mellonella with bioluminescent Mycobacterium bovis BCG lux. Using this infection model, mycobacterial dose dependent virulence can be observed, and a rapid readout of in vivo mycobacterial burden using bioluminescence measurements is easily achievable and reproducible. Although limitations exist, such as the lack of a fully annotated genome for transcriptomic analysis, ontological analysis against genetically similar insects can be carried out. As a low cost, rapid, and ethically acceptable model for tuberculosis, G. mellonella can be used as a pre-screen to determine drug efficacy and toxicity, and to determine comparative mycobacterial virulence prior to the use of conventional mammalian models. The use of the G. mellonella-mycobacteria model will lead to a reduction in the substantial number of animals currently used in tuberculosis research.
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Journal articleTang W, Ranganathan N, Shahrezaei V, et al., 2019,
MALDI-TOF mass spectrometry on intact bacteria combined with a refined analysis framework allows accurate classification of MSSA and MRSA.
, PLoS ONE, Vol: 14, Pages: 1-16, ISSN: 1932-6203Fast and reliable detection coupled with accurate data-processing and analysis of antibiotic-resistant bacteria is essential in clinical settings. In this study, we use MALDI-TOF on intact cells combined with a refined analysis framework to demonstrate discrimination between methicillin-susceptible (MSSA) and methicillin-resistant (MRSA) Staphylococcus aureus. By combining supervised and unsupervised machine learning methods, we firstly show that the mass spectroscopy data contains strong signal for the clustering of MSSA and MRSA. Then we concentrate on applying supervised learning to extract and verify the important features. A new workflow is proposed that allows for extracting a fixed set of reference peaks so that any new data can be aligned to it and hence consistent feature matrices can be obtained. Also note that by doing so we are able to examine the robustness of the important features that have been found. We also show that appropriate size of the benchmark data, appropriate alignment of the testing data and use of an optimal set of features via feature selection results in prediction accuracy over 90%. In summary, as proof-of-principle, our integrated experimental and bioinformatics study suggests a novel intact cell MALDI-TOF to be of great promise for fast and reliable detection of MRSA strains.
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Journal articleBallinger E, Mosior J, Hartman T, et al., 2019,
Opposing reactions in coenzyme A metabolism sensitize Mycobacterium tuberculosis to enzyme inhibition (vol 363, eaau8959, 2019)
, SCIENCE, Vol: 364, ISSN: 0036-8075 -
Journal articlePeriselneris J, Nwankwo L, Schelenz S, et al., 2019,
Posaconazole for the treatment of allergic bronchopulmonary aspergillosis in patients with cystic fibrosis.
, Journal of Antimicrobial Chemotherapy, Vol: 74, Pages: 1701-1703, ISSN: 0305-7453OBJECTIVES: Allergic bronchopulmonary aspergillosis (ABPA) can accelerate lung function decline in patients with cystic fibrosis (CF). Antifungal medication can be used in addition to systemic corticosteroid treatment. PATIENTS AND METHODS: We evaluated Aspergillus-specific IgE and the use of therapeutic drug monitoring of triazoles in a retrospective analysis of 32 patients. RESULTS: There was a significant reduction in Aspergillus IgE with posaconazole but not with other triazoles (P = 0.026). Aspergillus IgE levels were inversely correlated with the therapeutic drug level of posaconazole. CONCLUSIONS: These data suggest that posaconazole is better than comparator azoles at decreasing serological response to Aspergillus and that this response was better with therapeutic levels of posaconazole.
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