• Diversity of Bacteria Exhibiting Bile Acid-inducible 7α-dehydroxylation Genes in the Human Gut.

      Vital, Marius; Rud, Tatjana; Rath, Silke; Pieper, Dietmar H; Schlüter, Dirk; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Elsevier, 2019-01-01)
      The secondary bile acids deoxycholic acid (DCA) and lithocholic acid (LCA), formed by gut microbiota from primary bile acids via a multi-step 7α-dehydroxylation reaction, have wide-ranging effects on host metabolism and play an important role in health and disease. A few 7α-dehydroxylating strains have been isolated, where bile acid-inducible (bai) genes were organized in a gene cluster and encoded major enzymes involved. However, only little is known on diversity and abundance of intestinal bacteria catalysing DCA/LCA formation in the human gut in situ. In this study, we took the opportunity to screen metagenome-assembled genomes (MAGs) from sequence data of stool samples provided by two recent studies along with newly available gut-derived isolates for the presence of the bai gene cluster. We revealed in total 765 and 620 MAGs encoding the potential to form DCA/LCA that grouped into 21 and 26 metagenomic species, respectively. The majority of MAGs (92.4 and 90.3%) were associated with a Ruminococcaceae clade that still lacks an isolate, whereas less MAGs belonged to Lachnospiraceae along with eight new isolates (n total = 11) that contained the bai genes. Only a few MAGs were linked to Peptostreptococcaceae. Signatures for horizontal transfer of bai genes were observed. This study gives a comprehensive overview of the diversity of bai-exhibiting bacteria in the human gut highlighting the application of metagenomics to unravel potential functions hidden from current isolates. Eventually, isolates of the identified main MAG clade are required in order to prove their capability of 7α-dehydroxylating primary bile acids.
    • Molecular profiling of tissue biopsies reveals unique signatures associated with streptococcal necrotizing soft tissue infections

      Thänert, Robert; Itzek, Andreas; Hoßmann, Jörn; Hamisch, Domenica; Madsen, Martin Bruun; Hyldegaard, Ole; Skrede, Steinar; Bruun, Trond; Norrby-Teglund, Anna; Medina, Eva; et al. (Nature, 2019-08-26)
      Necrotizing soft tissue infections (NSTIs) are devastating infections caused by either a single pathogen, predominantly Streptococcus pyogenes, or by multiple bacterial species. A better understanding of the pathogenic mechanisms underlying these different NSTI types could facilitate faster diagnostic and more effective therapeutic strategies. Here, we integrate microbial community profiling with host and pathogen(s) transcriptional analysis in patient biopsies to dissect the pathophysiology of streptococcal and polymicrobial NSTIs. We observe that the pathogenicity of polymicrobial communities is mediated by synergistic interactions between community members, fueling a cycle of bacterial colonization and inflammatory tissue destruction. In S. pyogenes NSTIs, expression of specialized virulence factors underlies infection pathophysiology. Furthermore, we identify a strong interferon-related response specific to S. pyogenes NSTIs that could be exploited as a potential diagnostic biomarker. Our study provides insights into the pathophysiology of mono- and polymicrobial NSTIs and highlights the potential of host-derived signatures for microbial diagnosis of NSTIs.
    • Myeloid-Derived Suppressor Cells in Infection: A General Overview.

      Medina, Eva; Hartl, Dominik; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Karger, 2018-01-01)
      After initial infection, the immune response that serves to restrict the invading pathogen needs to be tightly calibrated in order to avoid collateral immunopathological damage. This calibration is performed by specialized suppressor mechanisms, which are capable of dampening overwhelming or unremitting inflammation in order to prevent tissue damage. Myeloid-derived suppressor cells (MDSC) are emerging as key players in counter-balancing inflammatory responses and pathogenesis during infection. However, some pathogens are able to exploit the suppressive activities of MDSC to favor pathogen persistence and chronic infections. In this article, we review the current knowledge about the importance of MDSC in the context of bacterial, virus, parasites, and fungal infections.
    • Longitudinal proliferation mapping in vivo reveals NADPH oxidase-mediated dampening of Staphylococcus aureus growth rates within neutrophils.

      Seiß, Elena A; Krone, Anna; Formaglio, Pauline; Goldmann, Oliver; Engelmann, Susanne; Schraven, Burkhart; Medina, Eva; Müller, Andreas J; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Nature publishing group, 2019-04-05)
      Upon the onset of inflammatory responses, bacterial pathogens are confronted with altered tissue microenvironments which can critically impact on their metabolic activity and growth. Changes in these parameters have however remained difficult to analyze over time, which would be critical to dissect the interplay between the host immune response and pathogen physiology. Here, we established an in vivo biosensor for measuring the growth rates of Staphylococcus aureus (S. aureus) on a single cell-level over days in an ongoing cutaneous infection. Using intravital 2-photon imaging and quantitative fluorescence microscopy, we show that upon neutrophil recruitment to the infection site and bacterial uptake, non-lethal dampening of S. aureus proliferation occurred. This inhibition was supported by NADPH oxidase activity. Therefore, reactive oxygen production contributes to pathogen containment within neutrophils not only by killing S. aureus, but also by restricting the growth rate of the bacterium.
    • Disruption of Coronin 1 Signaling in T Cells Promotes Allograft Tolerance while Maintaining Anti-Pathogen Immunity.

      Jayachandran, Rajesh; Gumienny, Aleksandra; Bolinger, Beatrice; Ruehl, Sebastian; Lang, Mathias Jakob; Fucile, Geoffrey; Mazumder, Saumyabrata; Tchang, Vincent; Woischnig, Anne-Kathrin; Stiess, Michael; et al. (Elsevier (Cell Press), 2019-01-15)
      The ability of the immune system to discriminate self from non-self is essential for eradicating microbial pathogens but is also responsible for allograft rejection. Whether it is possible to selectively suppress alloresponses while maintaining anti-pathogen immunity remains unknown. We found that mice deficient in coronin 1, a regulator of naive T cell homeostasis, fully retained allografts while maintaining T cell-specific responses against microbial pathogens. Mechanistically, coronin 1-deficiency increased cyclic adenosine monophosphate (cAMP) concentrations to suppress allo-specific T cell responses. Costimulation induced on microbe-infected antigen presenting cells was able to overcome cAMP-mediated immunosuppression to maintain anti-pathogen immunity. In vivo pharmacological modulation of this pathway or a prior transfer of coronin 1-deficient T cells actively suppressed allograft rejection. These results define a coronin 1-dependent regulatory axis in T cells important for allograft rejection and suggest that modulation of this pathway may be a promising approach to achieve long-term acceptance of mismatched allografts.
    • Mast cells as protectors of health.

      Dudeck, Anne; Köberle, Martin; Goldmann, Oliver; Meyer, Nicole; Dudeck, Jan; Lemmens, Stefanie; Rohde, M; Roldán, Nestor González; Dietze-Schwonberg, Kirsten; Orinska, Zane; et al. (Elsevier, 2018-11-20)
      Mast cells (MC), well known for their effector functions in Th2 skewed allergic and also autoimmune inflammation, become increasingly acknowledged for their role in protection of health. It is now clear that they are also key modulators of immune responses at interface organs like skin or gut. MC can prime tissues for adequate inflammatory responses and cooperate with dendritic cells in T cell activation. They also regulate harmful immune responses in trauma and help to successfully orchestrate pregnancy. This review focusses on the beneficial effects of mast cells on tissue homeostasis and elimination of toxins or venoms. MC can enhance pathogen clearance in many bacterial, viral, and parasite infections, e.g. by TLR2 triggered degranulation, secretion of antimicrobial cathelicidins, recruiting neutrophils or by providing extracellular DNA traps. The role of MC in tumors is more ambiguous, however, encouraging new findings show they can change the tumor microenvironment towards anti-tumor immunity when adequately triggered. Uterine tissue remodeling by α-chymase (MCP-5) is crucial for successful embryo implantation. MCP-4 and the tryptase MCP-6 emerge to be protective in CNS trauma by reducing inflammatory damage and excessive scar formation, thereby protecting axon growth. Last but not least, we see proteases like carboxypeptidase A released by FcεRI activated MC detoxify an increasing number of venoms and endogenous toxins. A better understanding of the plasticity of MC will help to improve these advantageous effects, and hint on ways to cut down detrimental MC actions.
    • An Interferon Signature Discriminates Pneumococcal From Staphylococcal Pneumonia.

      Strehlitz, Anja; Goldmann, Oliver; Pils, Marina C; Pessler, Frank; Medina, Eva; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany.; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH,Feodor-Lynen Str. 7, 30625 Hannover, Germany. (Frontiers, 2018-01-01)
      Streptococcus pneumoniae is the most common cause of community-acquired pneumonia (CAP). Despite the low prevalence of CAP caused by methicillin-resistant Staphylococcus aureus (MRSA), CAP patients often receive empirical antibiotic therapy providing coverage for MRSA such as vancomycin or linezolid. An early differentiation between S. pneumoniae and S. aureus pneumonia can help to reduce the use of unnecessary antibiotics. The objective of this study was to identify candidate biomarkers that can discriminate pneumococcal from staphylococcal pneumonia. A genome-wide transcriptional analysis of lung and peripheral blood performed in murine models of S. pneumoniae and S. aureus lung infection identified an interferon signature specifically associated with S. pneumoniae infection. Prediction models built using a support vector machine and Monte Carlo cross-validation, identified the combination of the interferon-induced chemokines CXCL9 and CXCL10 serum concentrations as the set of biomarkers with best sensitivity, specificity, and predictive power that enabled an accurate discrimination between S. pneumoniae and S. aureus pneumonia. The predictive performance of these biomarkers was further validated in an independent cohort of mice. This study highlights the potential of serum CXCL9 and CXCL10 biomarkers as an adjunctive diagnostic tool that could facilitate prompt and correct pathogen-targeted therapy in CAP patients.
    • Fluorescent Inorganic-Organic Hybrid Nanoparticles

      Neumeier, B. Lilli; Khorenko, Mikhail; Alves, Frauke; Goldmann, Oliver; Napp, Joanna; Schepers, Ute; Reichardt, Holger M.; Feldmann, Claus; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany.
      Inorganic‐organic hybrid nanoparticles (IOH‐NPs) with a general composition [ZrO]2+[RDyeOPO3]2−, [Ln]3+n/3[RDye(SO3)n]n−, [Ln(OH)]2+n/2[RDye(SO3)n]n−, or [LnO]+n[RDye(SO3)n]n− (Ln: lanthanide) are a novel class of nanomaterials for fluorescence detection and optical imaging. IOH‐NPs are characterized by an extremely high load of the fluorescent dye (70–85 wt‐%), high photochemical stability, straightforward aqueous synthesis, low material complexity, intense emission and high cell uptake at low toxicity. Besides full‐color emission, IOH‐NPs are suitable for multimodal imaging, singlet‐oxygen generation as well as drug delivery and drug release. This focus review presents the material concept of the IOH‐NPs as well as their synthesis and characterization. Their characteristic features are illustrated by selected in vitro and in vivo studies to initiate application in biology and medicine.
    • Zirconyl Clindamycinphosphate Antibiotic Nanocarriers for Targeting Intracellular Persisting

      Heck, Joachim G.; Rox, Katharina; Lünsdorf, Heinrich; Lückerath, Thorsten; Klaassen, Nicole; Medina, Eva; Goldmann, Oliver; Feldmann, Claus; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany.
      [ZrO]2+[CLP]2– (CLP: clindamycinphosphate) inorganic–organic hybrid nanoparticles (IOH-NPs) represent a novel strategy to treat persisting, recurrent infections with multiresistant Staphylococcus aureus. [ZrO]2+[CLP]2– is prepared in water and contains the approved antibiotic with unprecedented high load (82 wt % CLP per nanoparticle). The IOH-NPs result in 70–150-times higher antibiotic concentrations at difficult-to-reach infection sites, offering new options for improved drug delivery for chronic and difficult-to-treat infections.
    • Changed Expression of Cytoskeleton Proteins During Lung Injury in a Mouse Model of Infection.

      Ferrer-Navarro, Mario; Strehlitz, Anja; Medina, Eva; Vila, Jordi
      Infections by are a major cause of morbidity and mortality worldwide, often causing community-acquired pneumonia, otitis media and also bacteremia and meningitis. Studies on are mainly focused on its virulence or capacity to evade the host immune system, but little is known about the injury caused in lungs during a pneumococcal infection. Herein we investigated this issue comparing the proteome profile of lungs from infected mice with control mice by means of difference gel electrophoresis (DIGE) technology. In order to obtain reliable results three biological replicas were used, and four technical replicas were carried out in each biological replica. Proteomic comparison was performed at two time points: 24 and 48 h post infection. A total of 91 proteins were identified with different abundance. We found important changes in the protein profiles during pneumococcal infection mainly associated with regulation of vesicle-mediated transport, wound healing, and cytoskeleton organization. In conclusion, the results obtained show that the cytoskeleton of the host cell is modified in infection.
    • SCM, the M Protein of Streptococcus canis Binds Immunoglobulin G.

      Bergmann, Simone; Eichhorn, Inga; Kohler, Thomas P; Hammerschmidt, Sven; Goldmann, Oliver; Rohde, M; Fulde, Marcus; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr.7, 38124 Braunschweig, Germany. (2017)
      The M protein of Streptococcus canis (SCM) is a virulence factor and serves as a surface-associated receptor with a particular affinity for mini-plasminogen, a cleavage product of the broad-spectrum serine protease plasmin. Here, we report that SCM has an additional high-affinity immunoglobulin G (IgG) binding activity. The ability of a particular S. canis isolate to bind to IgG significantly correlates with a scm-positive phenotype, suggesting a dominant role of SCM as an IgG receptor. Subsequent heterologous expression of SCM in non-IgG binding S. gordonii and Western Blot analysis with purified recombinant SCM proteins confirmed its IgG receptor function. As expected for a zoonotic agent, the SCM-IgG interaction is species-unspecific, with a particular affinity of SCM for IgGs derived from human, cats, dogs, horses, mice, and rabbits, but not from cows and goats. Similar to other streptococcal IgG-binding proteins, the interaction between SCM and IgG occurs via the conserved Fc domain and is, therefore, non-opsonic. Interestingly, the interaction between SCM and IgG-Fc on the bacterial surface specifically prevents opsonization by C1q, which might constitute another anti-phagocytic mechanism of SCM. Extensive binding analyses with a variety of different truncated SCM fragments defined a region of 52 amino acids located in the central part of the mature SCM protein which is important for IgG binding. This binding region is highly conserved among SCM proteins derived from different S. canis isolates but differs significantly from IgG-Fc receptors of S. pyogenes and S. dysgalactiae sub. equisimilis, respectively. In summary, we present an additional role of SCM in the pathogen-host interaction of S. canis. The detailed analysis of the SCM-IgG interaction should contribute to a better understanding of the complex roles of M proteins in streptococcal pathogenesis.
    • Identification of a novel subset of myeloid-derived suppressor cells during chronic staphylococcal infection that resembles immature eosinophils.

      Goldmann, Oliver; Beineke, Andreas; Medina, Eva; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunchweig, Germany. (2017-09-23)
      We have previously reported that myeloid-derived suppressor cells (MDSC), which are a heterogeneous population of immunosuppressive immature myeloid cells, expanded during chronic Staphylococcus aureus infection and promoted bacterial persistence by inhibiting effector T cells. Two major MDSC subsets including monocytic MDSCs (M-MDSC) and granulocytic MDSCs (G-MDSC) have been described to date. Here, we identified a new subset of MDSC (Eo-MDSC) in S. aureus-infected mice that phenotypically resembles eosinophils. Eo-MDSC exhibit eosinophilic cytoplasmic granules and express CD11b, the eosinophil marker Syglec-F, variable levels of CCR3 and low levels of IL-5R. Furthermore, Eo-MDSC accumulated at the site of infection and exerted a potent immunosuppressive effect on T cell responses that was mediated by nitric oxide-dependent depletion of L-arginine. Increased in the number of Eo-MDSC by adoptive transfer caused a significant exacerbation of infection in S. aureus-infected mice. This study sheds new light on the heterogeneity and complexity of MDSC during chronic infection.
    • IL-10 Plays Opposing Roles during Staphylococcus aureus Systemic and Localized Infections.

      Leech, John M; Lacey, Keenan A; Mulcahy, Michelle E; Medina, Eva; McLoughlin, Rachel M (2017-03-15)
      IL-10 is a potent anti-inflammatory mediator that plays a crucial role in limiting host immunopathology during bacterial infections by controlling effector T cell activation. Staphylococcus aureus has previously been shown to manipulate the IL-10 response as a mechanism of immune evasion during chronic systemic and biofilm models of infection. In the present study, we demonstrate divergent roles for IL-10 depending on the site of infection. During acute systemic S. aureus infection, IL-10 plays an important protective role and is required to prevent bacterial dissemination and host morbidity by controlling effector T cells and the associated downstream hyperactivation of inflammatory phagocytes, which are capable of host tissue damage. CD19(+)CD11b(+)CD5(+) B1a regulatory cells were shown to rapidly express IL-10 in a TLR2-dependent manner in response to S. aureus, and adoptive transfer of B1a cells was protective during acute systemic infection in IL-10-deficient hosts. In contrast, during localized s.c. infection, IL-10 production plays a detrimental role by facilitating bacterial persistence via the same mechanism of controlling proinflammatory T cell responses. Our findings demonstrate that induction of IL-10 has a major influence on disease outcome during acute S. aureus infection. Too much IL-10 at one end of the scale may suppress otherwise protective T cell responses, thus facilitating persistence of the bacteria, and at the other end, too little IL-10 may tend toward fatal host-mediated pathology through excessive activation of T cells and associated phagocyte-mediated damage.
    • Host-inherent variability influences the transcriptional response of Staphylococcus aureus during in vivo infection.

      Thänert, Robert; Goldmann, Oliver; Beineke, Andreas; Medina, Eva; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017-02-03)
      The rise of antibiotic resistance calls for alternative strategies to treat bacterial infections. One attractive strategy is to directly target bacterial virulence factors with anti-virulence drugs. The expression of virulence traits by pathogens is, however, not constitutive but rather induced by the level of stress encountered within the host. Here we use dual RNA sequencing (RNA-seq) to show that intrinsic variability in the level of host resistance greatly affects the pathogen's transcriptome in vivo. Through analysis of the transcriptional profiles of host and pathogen during Staphylococcus aureus infection of two mouse strains, shown to be susceptible (A/J) or resistant (C57BL/6) to the pathogen, we demonstrate that the expression of virulence factors is dependent on the encountered host resistance. We furthermore provide evidence that this dependence strongly influences the efficacy of anti-virulence strategies, highlighting a potential limitation for the implementation of these strategies.
    • Host-inherent variability influences the transcriptional response of Staphylococcus aureus during in vivo infection

      Thänert, Robert; Goldmann, Oliver; Beineke, Andreas; Medina, Eva; Helmholtz Centre for infection research. Inhoffenstr. 7. 38124 Braunschweig, Germany. (2017-02-03)
    • Differential Contributions of the Complement Anaphylotoxin Receptors C5aR1 and C5aR2 to the Early Innate Immune Response against Staphylococcus aureus Infection.

      Horst, Sarah A; Itzek, Andreas; Klos, Andreas; Beineke, Andreas; Medina, Eva; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2015)
      The complement anaphylatoxin C5a contributes to host defense against Staphylococcus aureus. In this study, we investigated the functional role of the two known C5a receptors, C5aR1 and C5aR2, in the host response to S. aureus. We found that C5aR1(-/)(-) mice exhibited greater susceptibility to S. aureus bloodstream infection than wild type and C5aR2(-/)(-) mice, as demonstrated by the significantly higher bacterial loads in the kidneys and heart at 24 h of infection, and by the higher levels of inflammatory IL-6 in serum. Histological and immunohistochemistry investigation of infected kidneys at 24 h after bacterial inoculation revealed a discrete infiltration of neutrophils in wild type mice but already well-developed abscesses consisting of bacterial clusters surrounded by a large number of neutrophils in both C5aR1(-/)(-) and C5aR2(-/)(-) mice. Furthermore, blood neutrophils from C5aR1(-/)(-) mice were less efficient than those from wild type or C5aR2(-/)(-) mice at killing S. aureus. The requirement of C5aR1 for efficient killing of S. aureus was also demonstrated in human blood after disrupting C5a-C5aR1 signaling using specific inhibitors. These results demonstrated a role for C5aR1 in S. aureus clearance as well as a role for both C5aR1 and C5aR2 in the orchestration of the inflammatory response during infection.
    • Iron-chelating agent desferrioxamine stimulates formation of neutrophil extracellular traps (NETs) in human blood-derived neutrophils.

      Völlger, Lena; Akong-Moore, Kathryn; Cox, Linda; Goldmann, Oliver; Wang, Yanming; Schäfer, Simon T; Naim, Hassan Y; Nizet, Victor; von Köckritz-Blickwede, Maren; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016-07)
      Neutrophil extracellular trap (NET) formation is a significant innate immune defense mechanism against microbial infection that complements other neutrophil functions including phagocytosis and degranulation of antimicrobial peptides. NETs are decondensed chromatin structures in which antimicrobial components (histones, antimicrobial peptides and proteases) are deployed and mediate immobilization of microbes. Here we describe an effect of iron chelation on the phenotype of NET formation. Iron-chelating agent desferrioxamine (DFO) showed a modest but significant induction of NETs by freshly isolated human neutrophils as visualized and quantified by immunocytochemistry against histone-DNA complexes. Further analyses revealed that NET induction by iron chelation required NADPH-dependent production of reactive oxygen species (ROS) as well as protease and peptidyl-arginine-deiminase 4 (PAD4) activities, three key mechanistic pathways previously linked to NET formation. Our results demonstrate that iron chelation by DFO contributes to the formation of NETs and suggest a target for pharmacological manipulation of NET activity.
    • Global Regulation of Gene Expression by the MafR Protein of Enterococcus faecalis.

      Ruiz-Cruz, Sofía; Espinosa, Manuel; Goldmann, Oliver; Bravo, Alicia; Helmholtz Centre for infection research, Inhoffenstr. 7, D-38124 Braunschweig, Germany. (2015)
      Enterococcus faecalis is a natural inhabitant of the human gastrointestinal tract. However, as an opportunistic pathogen, it is able to colonize other host niches and cause life-threatening infections. Its adaptation to new environments involves global changes in gene expression. The EF3013 gene (here named mafR) of E. faecalis strain V583 encodes a protein (MafR, 482 residues) that has sequence similarity to global response regulators of the Mga/AtxA family. The enterococcal OG1RF genome also encodes the MafR protein (gene OG1RF_12293). In this work, we have identified the promoter of the mafR gene using several in vivo approaches. Moreover, we show that MafR influences positively the transcription of many genes on a genome-wide scale. The most significant target genes encode components of PTS-type membrane transporters, components of ABC-type membrane transporters, and proteins involved in the metabolism of carbon sources. Some of these genes were previously reported to be up-regulated during the growth of E. faecalis in blood and/or in human urine. Furthermore, we show that a mafR deletion mutant strain induces a significant lower degree of inflammation in the peritoneal cavity of mice, suggesting that enterococcal cells deficient in MafR are less virulent. Our work indicates that MafR is a global transcriptional regulator. It might facilitate the adaptation of E. faecalis to particular host niches and, therefore, contribute to its potential virulence.
    • Genome sequence of the pink-pigmented marine bacterium Loktanella hongkongensis type strain (UST950701-009P(T)), a representative of the Roseobacter group.

      Lau, Stanley Ck; Riedel, Thomas; Fiebig, Anne; Han, James; Huntemann, Marcel; Petersen, Jörn; Ivanova, Natalia N; Markowitz, Victor; Woyke, Tanja; Göker, Markus; et al. (2015)
      Loktanella hongkongensis UST950701-009P(T) is a Gram-negative, non-motile and rod-shaped bacterium isolated from a marine biofilm in the subtropical seawater of Hong Kong. When growing as a monospecies biofilm on polystyrene surfaces, this bacterium is able to induce larval settlement and metamorphosis of a ubiquitous polychaete tubeworm Hydroides elegans. The inductive cues are low-molecular weight compounds bound to the exopolymeric matrix of the bacterial cells. In the present study we describe the features of L. hongkongensis strain DSM 17492(T) together with its genome sequence and annotation and novel aspects of its phenotype. The 3,198,444 bp long genome sequence encodes 3104 protein-coding genes and 57 RNA genes. The two unambiguously identified extrachromosomal replicons contain replication modules of the RepB and the Rhodobacteraceae-specific DnaA-like type, respectively.
    • High-resolution transcriptomic analysis of the adaptive response of Staphylococcus aureus during acute and chronic phases of osteomyelitis.

      Szafranska, Anna K; Oxley, Andrew P A; Chaves-Moreno, Diego; Horst, Sarah A; Roßlenbroich, Steffen; Peters, Georg; Goldmann, Oliver; Rohde, Manfred; Sinha, Bhanu; Pieper, Dietmar H; et al. (2014)
      Osteomyelitis is a difficult-to-eradicate bone infection typically caused by Staphylococcus aureus. In this study, we investigated the in vivo transcriptional adaptation of S. aureus during bone infection. To this end, we determined the transcriptome of S. aureus during the acute (day 7) and chronic (day 28) phases of experimental murine osteomyelitis using RNA sequencing (RNA-Seq). We identified a total of 180 genes significantly more highly expressed by S. aureus during acute or chronic in vivo infection than under in vitro growth conditions. These genes encoded proteins involved in gluconeogenesis, proteolysis of host proteins, iron acquisition, evasion of host immune defenses, and stress responses. At the regulatory level, sarA and -R and saeR and -S as well as the small RNA RsaC were predominantly expressed by S. aureus during in vivo infection. Only nine genes, including the genes encoding the arginine deiminase (ADI) pathway and those involved in the stringent response, were significantly more highly expressed by S. aureus during the chronic than the acute stage of infection. Analysis by quantitative reverse transcription-PCR (qRT-PCR) of a subset of these in vivo-expressed genes in clinical specimens yielded the same results as those observed in the murine system. Collectively, our results show that during acute osteomyelitis, S. aureus induced the transcription of genes that mediate metabolic adaptation, immune evasion, and replication. During the chronic phase, however, S. aureus switched its transcriptional response from a proliferative to a persistence mode, probably driven by the severe deficiency in nutrient supplies. Interfering with the survival strategies of S. aureus during chronic infection could lead to more effective treatments.