VAAM-Jahrestagung 2011 Karlsruhe, 3.–6. April 2011

hyphae as well as conidia. This reactive oxygen intermediates (ROI)dependent mechanism results in sticky filaments consisting of nuclear DNAdecorated with histones and fungicidal proteins. Coincubation of A.fumigatus with neutrophils revealed that the intensity of NET formation ofunstimulated, human neutrophils is strain- and morphotype-dependent.Furthermore the killing of A. fumigatus conidia was not influenced by theamount of released extracellular DNA. However hyphae seemed to bedamaged by NETs after a longer incubation time of 12h. Our data suggestthat NETs prevent further spreading, but apparently do not represent themajor factor for killing. We are currently investigating strain- and mutantdependentNET formation that will be discussed.[1] Bruns et al (2010): Plos Pathogens 6: e1000873.[2] Brakhage, A.A. et al (2010): Curr Op Microbiol 13:409.MPP011Pathogenicity factor of the Streptomyces strains causingpotato scab disease other than thaxtomineG. Khodakaramian*, G. HemmatiPlant Protection, Bu-Ali Sina University, Hamedan, IranA few Streptomyces species are pathogenic on some plants such as potato.Main pathogenicity factors among this species on potato are thaxtomine,concanamycin and a compound named as FD-981. Potato scab disease isone of the most important diseases in potato growing area in hamedanprovince. Potato tubers shown raised, netted, shallow and deep pitted lesionsymptoms were collected from many potato fields and the Streptomycesstrains were isolated. Based on the phenotypic features and inducedsymptoms the isolated streptomyces strains were not uniforms. Theyinduced symptoms on the tested plants including potato, parsnip, horseradish, carrot and other tested plants. Most of the tested strains harbored alinear plasmid exemined by pulsed field gel electrophoresis and they hadsequences related to insertion sequences, nec1 and thaxthomin biosyntheticgenes. Raised and netted scab disease inducing strains produced thaxtomindetermined by thin layer chromatography but not pitted lesion inducingstrains. The last strains which did not produced thaxtomin also did nothybridized to thaxtomin biosynthesis gene probes. Deep pitted inducingrepresentatives strains produced disease inducing toxins other thanthaxtomin.[1] Bukhalid et al (1998): nec1, a gene conferring a necrogenic phenotype, is conserved in plantpathogenicStreptomyces spp. and linked to a transposase pseudogene. Mol.Plant-Microbe Interact.,11, 660-967[2] Goyer et al (1998): Pathogenicity of Streptomyces scabies mutants altered in thaxtomin Aproduction Phytopathology 88, 442-445.[3] Kers et al (2005): A large, mobile pathogenicity island confers plant pathogenicity onStreptomyces species. Mol. Microbiol. .55(4):1025-33.[4] Loraia et al (2006): Evolution of plant pathogenicity in Streptomyces. Annu. Rev. Phytopathol.44:469-87.MPP012Phenotypic properties of clinical relevance ofStenotrophomonas maltophilia isolates in relation to theirgenetic subgroupsM. Adamek* 1 , T. Schwartz, R. FischerInstitute of Functional Interfaces (IFG), Karlsruhe Institute of Technology(KIT), Eggenstein-Leopoldshafen, GermanyStenotrophomonas maltophilia is a highly versatile bacterial species,belonging to the γ-β subclass of proteobacteria. It is ubiquitously distributedin the environment, but recently its role as nosocomial pathogen becamemore evident. In our previous work we analyzed genetic diversity of S.maltophilia by rep-PCR fingerprinting and gyrB gene sequencing, for acollection of 171 environmental and clinical strains. This revealed 11genetic subgroups for S. maltophilia. A subset of 50 representative isolatesfor these groups was then used for further investigation of phenotypicproperties. With respect to the increasing importance as an opportunisticpathogen, potential virulence traits, as the production of extracellularproteases, haemolysins and siderophores were investigated. Furthermore,factors supporting colonization of a human host were examined byswimming and twitching motility and biofilm assays. Virulence was testedby co-culturing the bacteria with the amoebae Dictyostelium discoideum andAcanthamoeba castellanii as model organisms. After testing twenty differentantibiotics on a small subset of strains, gentamicin, vancomycin,norfloxacin, tetracycline and co-trimoxazole, were chosen to determineMICs for the 50 S. maltophilia isolates.Nearly all investigated isolates produced proteases and haemolysins and allof them produced siderophores. Motility assays revealed differences inswimming and twitching motility. Biofilm formation generally differed, butdid not correspond to their genetic subgroups of the isolates. An exception isthat all isolates from environmental group E2 showed only slight potentialfor biofilm formation. Virulence for amoebae was shown for about one thirdof the tested isolates and was in no relationship to clinical or environmentalorigin. All isolates were resistant to vancomycin and most to gentamicin.Most of them showed intermediate MICs for norfloxacin and tetracycline,and all isolates were susceptible to co-trimoxazole.For motility assays, biofilm formation, virulence and antibiotic resistancegenerally no correlation to the previously defined genetic groups was found.In this context it was expected that housekeeping genes and rep-PCRfingerprints are not suitable markers to determine phenotypic properties of S.maltophilia.MPP013Human Formyl Peptide Receptor 2 Senses HighlyPathogenic Staphylococcus aureusD. Kretschmer* 1 , A.-K. Gleske 1 , M. Rautenberg 1 , R. Wang 2 , M. Köberle 1 ,E. Bohn 1 , T. Schöneberg 3 , M.-J. Rabiet 4 , F. Boulay 4 , S.J. Klebanoff 5 ,K.A. van Kessel 6 , J.A. van Strijp 6 , M. Otto 2 , A. Peschel 11 Cellular and Molecular Microbiology Division, Interfaculty Institute ofMicrobiology and Infection Medicine, University, Tübingen, Germany2 National Institute of Allergy and Infectious Diseases, US NationalInstitutes of Health, Bethesda, USA3 Medical Faculty, Institute of Biochemistry, University of Leipzig, Leipzig,Germany4 Biochemistry and Biophysics Laboratory of Integrated Systems, Grenoble,France5 University of Washington School of Medicine, Seattle, USA6 Medical Microbiology, University Medical Center Utrecht, Utrecht,NetherlandsVirulence of the emerging Community-Associated Methicillin-ResistantStaphylococcus aureus (CA-MRSA) and other highly pathogenic S. aureusdepends on the recently discovered Phenol-Soluble Modulin (PSM) peptidetoxins, which combine the capacities to attract and lyse neutrophils. Themolecular basis of PSM-stimulated neutrophil recruitment has remainedunknown. We demonstrate that the human FPR2/ALX receptor, whosefunction has previously remained elusive, senses PSMs at nanomolarconcentrations and initiates the exuberant proinflammatory neutrophilresponses to CA-MRSA. Specific blocking of this receptor or deletion ofPSM genes in CA-MRSA led to severely diminished capacities ofneutrophils to detect CA-MRSA. Thus, the innate immune system uses apreviously unrecognized mechanism to sense highly virulent bacterialpathogens. This G protein-coupled receptor represents an attractive target fornew anti-infective or anti-inflammatory strategies.MPP014Effects of increasing concentrations of antibiotics on theresistance situation of selected human pathogenicbacterial generaS. Schmidt*, J. Winter, C. GallertInstitute of Bioengineering and Biotechnology of Waste Water, KarlsruheInstitute of Technology (KIT), Karlsruhe, GermanySince the development and use of antibiotics the number of resistant bacteriaincreases constantly. Multidrug-resistant pathogens become more and moreproblematic, especially due to nosocomial infections. These bacteria, as wellas antibiotics and their metabolites, enter waste water by human excretions.To the present state of the art no or no complete degradation of antibioticsand other drugs takes place in waste water treatment plants. Also theretention of drugs and bacteria, e.g. by adsorption to sludge particles, isinsufficient, so in WWTP effluents already antibiotic concentrations inexcess of the effective concentration were measured (2, 3, 5). By the use ofsewage sludge and manure as fertilizers antibiotics and bacteria also reachsoil and surface water (1, 4, 11). Moreover, bacteria have the ability todevelop resistances at sub lethal concentrations of antibiotics and toexchange resistance genes with other bacteria via horizontal gene transfer.So the aim of our study was the investigation of the development ofresistances in the genera Acinetobacter sp., Enterococcus sp., Klebsiella sp.and Staphylococcus sp. from sewage sludge towards 4 selected antibioticsspektrum | Tagungsband 2011