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Dive into the research topics where Maren Stämmler is active.

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Featured researches published by Maren Stämmler.


Journal of Clinical Microbiology | 2003

Prospective Study of the Performance of Vibrational Spectroscopies for Rapid Identification of Bacterial and Fungal Pathogens Recovered from Blood Cultures

Kees Maquelin; Carolin Kirschner; Lin-P'ing Choo-Smith; N.A. Ngo-Thi; T. van Vreeswijk; Maren Stämmler; Hubert P. Endtz; Hajo Bruining; Dieter Naumann; Gerwin J. Puppels

ABSTRACT Rapid identification of microbial pathogens reduces infection-related morbidity and mortality of hospitalized patients. Raman spectra and Fourier transform infrared (IR) spectra constitute highly specific spectroscopic fingerprints of microorganisms by which they can be identified. Little biomass is required, so that spectra of microcolonies can be obtained. A prospective clinical study was carried out in which the causative pathogens of bloodstream infections in hospitalized patients were identified. Reference libraries of Raman and IR spectra of bacterial and yeast pathogens highly prevalent in bloodstream infections were created. They were used to develop identification models based on linear discriminant analysis and artificial neural networks. These models were tested by carrying out vibrational spectroscopic identification in parallel with routine diagnostic phenotypic identification. Whereas routine identification has a typical turnaround time of 1 to 2 days, Raman and IR spectra of microcolonies were collected 6 to 8 h after microbial growth was detected by an automated blood culture system. One hundred fifteen samples were analyzed by Raman spectroscopy, of which 109 contained bacteria and 6 contained yeasts. One hundred twenty-one samples were analyzed by IR spectroscopy. Of these, 114 yielded bacteria and 7 were positive for yeasts. High identification accuracy was achieved in both the Raman (92.2%, 106 of 115) and IR (98.3%, 119 of 121) studies. Vibrational spectroscopic techniques enable simple, rapid, and accurate microbial identification. These advantages can be easily transferred to other applications in diagnostic microbiology, e.g., to accelerate identification of fastidious microorganisms.


Journal of Microbiological Methods | 2014

Insufficient discriminatory power of MALDI-TOF mass spectrometry for typing of Enterococcus faecium and Staphylococcus aureus isolates.

Peter Lasch; Carola Fleige; Maren Stämmler; Franziska Layer; Ulrich Nübel; Wolfgang Witte; Guido Werner

MALDI-TOF mass spectrometry (MALDI-TOF MS) is increasingly used as a reliable technique for species identification of bacterial pathogens. In this study we investigated the question of whether MALDI-TOF MS can be used for accurate sub-differentiation of strains and isolates of two important nosocomial pathogens Enterococcus faecium and Staphylococcus aureus. For this purpose, a selection of 112 pre-characterized E. faecium isolates (clonal complexes CC2, CC5, CC9, CC17, CC22, CC25, CC26, CC92 altogether 52 multilocus sequence types) and 59 diverse S. aureus isolates (mostly methicillin resistant; CC5, CC8, CC22, CC30, CC45, CC398) were studied using a combination of MALDI-TOF MS and advanced methods of spectral data analysis. The strategy of MS data evaluation included manual peak inspection on the basis of pseudo gel views, unsupervised hierarchical cluster analysis and supervised artificial neural network (ANN) analysis. We were capable of differentiating patterns of hospital-associated E. faecium isolates (CC17) from other strains of E. faecium with 87% accuracy, but failed to identify lineage-specific biomarker peaks. For S. aureus pattern analyses we were able to confirm a number of signals described in previous studies, but often failed to identify biomarkers that would allow a consistent and reliable identification of phylogenetic lineages, clonal complexes or sequence types. Hence, the discriminatory power of MALDI-TOF MS was found to be insufficient for reliably sub-differentiating E. faecium and S. aureus isolates to the level of distinct clones or clonal complexes, such as assessed by MLST. Further, a comparison between peak patterns of susceptible and resistant isolates did not identify statistically relevant marker peaks linked to glycopeptide resistance determinants (vanA, vanB) in E. faecium, or the methicillin resistance determinant (mecA) in S. aureus.


Analyst | 2009

Rapid identification of Burkholderia cepacia complex species including strains of the novel Taxon K, recovered from cystic fibrosis patients by intact cell MALDI-ToF mass spectrometry.

Alejandro Miñán; Alejandra Bosch; Peter Lasch; Maren Stämmler; Diego Serra; José Degrossi; Blanca Gatti; Carlos Vay; Miguel D'Aquino; Osvaldo Yantorno; Dieter Naumann

Two approaches based on intact cell matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (IC-MALDI-ToF MS) have been evaluated in order to discriminate and identify nine former Burkholderia cepacia complex (Bcc) species, Burkholderia contaminans belonging to the novel Taxon K, Burkholderia gladioli, and the most relevant non-fermentative (NF) Gram-negative rods recovered from cystic fibrosis (CF) sputum cultures. In total, 146 clinical isolates and 26 reference strains were analysed. IC mass spectra were obtained with high reproducibility applying a recently developed inactivation protocol which is based on the extraction of microbial proteins by trifluoroacetic acid (TFA). In a first approach, spectral analysis was carried out by means of a gel-view representation of mass spectra, which turned out to be useful to recognize specific identifying biomarker proteins (SIBPs). A series of prominent mass peaks, mainly assigned to constitutively expressed proteins, were selected as SIBPs for identifications at the genus and species level. Two distinctive mass peaks present in B. contaminans spectra (7501 and 7900 Da) were proposed as SIBPs for the identification of this novel species. A second approach of spectral analysis based on data reduction, feature selection and subsequent hierarchical cluster analysis was used to obtain an objective discrimination of all species analysed. Both complementary modalities of analyzing complex IC-MALDI-ToF MS data open the path towards a rapid, accurate and objective means of routine clinical microbiology diagnosis of pathogens from sputum samples of CF patients.


Journal of Biological Chemistry | 2016

Growth-Related Metabolism of the Carbon Storage Poly-3-Hydroxybutyrate in Legionella pneumophila

Nadine Gillmaier; Eva Schunder; Erika Kutzner; Hana Tlapák; Kerstin Rydzewski; Vroni Herrmann; Maren Stämmler; Peter Lasch; Wolfgang Eisenreich; Klaus Heuner

Legionella pneumophila, the causative agent of Legionnaires disease, has a biphasic life cycle with a switch from a replicative to a transmissive phenotype. During the replicative phase, the bacteria grow within host cells in Legionella-containing vacuoles. During the transmissive phenotype and the postexponential (PE) growth phase, the pathogens express virulence factors, become flagellated, and leave the Legionella-containing vacuoles. Using 13C labeling experiments, we now show that, under in vitro conditions, serine is mainly metabolized during the replicative phase for the biosynthesis of some amino acids and for energy generation. During the PE phase, these carbon fluxes are reduced, and glucose also serves as an additional carbon substrate to feed the biosynthesis of poly-3-hydroxybuyrate (PHB), an essential carbon source for transmissive L. pneumophila. Whole-cell FTIR analysis and comparative isotopologue profiling further reveal that a putative 3-ketothiolase (Lpp1788) and a PHB polymerase (Lpp0650), but not enzymes of the crotonyl-CoA pathway (Lpp0931–0933) are involved in PHB metabolism during the PE phase. However, the data also reflect that additional bypassing reactions for PHB synthesis exist in agreement with in vivo competition assays using Acanthamoeba castellannii or human macrophage-like U937 cells as host cells. The data suggest that substrate usage and PHB metabolism are coordinated during the life cycle of the pathogen.


Journal of Biophotonics | 2010

Type-IV pili spectroscopic markers: Applications in the quantification of piliation levels in Moraxella bovis cells by a FT-IR ANN-based model

Alejandra Bosch; Claudia I. Prieto; Diego Omar Serra; Pablo Martina; Maren Stämmler; Dieter Naumann; Jürgen M. Schmitt; Osvaldo Yantorno

Type-IV pili are cell surface organelles found in a wide variety of Gram-negative bacteria. They have traditionally been detected by electron microscopy and ELISA techniques. However, these methodologies are not appropriate for the rapid discrimination and quantification of piliated and nonpiliated cells in industrial or field conditions. Here, the analysis of FT-IR spectra of piliated, nonpiliated and sheared Moraxella bovis cells, together with purified pili suspensions spectra, allowed the identification of 3 IR regions associated to spectroscopic markers of Type-IV pili: 1750-1600, 1450-1350 and 1280-950 cm(-1). Such IR-specific markers were found for piliated cells grown in different culture systems (liquid or solid media), independently of the strain or pili serotype. They were also sensitive to pili expression levels. Therefore, on the bases of these specific spectral features, an FT-IR ANN-based model was developed to classify piliation levels in 5 distinct groups. An overall classification rate of almost 90% demonstrates the strong potential of the ANN system developed to monitor M. bovis cultures in vaccine production.


International Journal of Systematic and Evolutionary Microbiology | 2018

Burkholderia puraquae sp. nov., a novel species of the Burkholderia cepacia complex isolated from hospital settings and agricultural soils

Pablo Martina; Mariana Leguizamón; Claudia I. Prieto; Sílvia A. Sousa; Patricia Montanaro; Walter O. Draghi; Maren Stämmler; Marisa Bettiol; Carla C. C. R. de Carvalho; Juliana Palau; Cecilia Figoli; Florencia Alvarez; Silvina Benetti; Sergio Lejona; Cecilia Vescina; Julián Ferreras; Peter Lasch; Antonio Lagares; Angeles Zorreguieta; Jorge H. Leitão; Osvaldo Yantorno; Alejandra Bosch

Bacteria from the Burkholderia cepacia complex (Bcc) are capable of causing severe infections in patients with cystic fibrosis (CF). These opportunistic pathogens are also widely distributed in natural and man-made environments. After a 12-year epidemiological surveillance involving Bcc bacteria from respiratory secretions of Argentinean patients with CF and from hospital settings, we found six isolates of the Bcc with a concatenated species-specific allele sequence that differed by more than 3 % from those of the Bcc with validly published names. According to the multilocus sequence analysis (MLSA), these isolates clustered with the agricultural soil strain, Burkholderia sp. PBP 78, which was already deposited in the PubMLST database. The isolates were examined using a polyphasic approach, which included 16S rRNA, recA, Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), DNA base composition, average nucleotide identities (ANIs), fatty acid profiles, and biochemical characterizations. The results of the present study demonstrate that the seven isolates represent a single novel species within the Bcc, for which the name Burkholderia puraquae sp. nov. is proposed. Burkholderia puraquae sp. nov. CAMPA 1040T (=LMG 29660T=DSM 103137T) was designated the type strain of the novel species, which can be differentiated from other species of the Bcc mainly from recA gene sequence analysis, MLSA, ANIb, MALDI-TOF MS analysis, and some biochemical tests, including the ability to grow at 42 °C, aesculin hydrolysis, and lysine decarboxylase and β-galactosidase activities.


Clinical Microbiology and Infection | 2008

MRSA in Austria—an overview

Karina Krziwanek; Christoph Luger; B. Sammer; Sabine Stumvoll; Maren Stämmler; Ulrich Sagel; Wolfgang Witte; Helmut Mittermayer


Analyst | 2011

Observation of content and heterogeneity of poly-β-hydroxybutyric acid (PHB) in Legionella bozemanii by vibrational spectroscopy

Antje Hermelink; Maren Stämmler; Dieter Naumann


Faraday Discussions | 2016

Rapid characterisation of Klebsiella oxytoca isolates from contaminated liquid hand soap using mass spectrometry, FTIR and Raman spectroscopy

Ralf Dieckmann; Jens A. Hammerl; Hartmut Hahmann; Amal Wicke; Sylvia Kleta; Piotr Wojciech Dabrowski; Andreas Nitsche; Maren Stämmler; Sascha Al Dahouk; Peter Lasch


Clinical Microbiology and Infection | 2008

MRSA in Austriaan overview

Karina Krziwanek; Christoph Luger; B. Sammer; Sabine Stumvoll; Maren Stämmler; Ulrich Sagel; Wolfgang Witte; Helmut Mittermayer

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Alejandra Bosch

National University of La Plata

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Osvaldo Yantorno

National University of La Plata

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Claudia I. Prieto

National University of La Plata

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Pablo Martina

National University of La Plata

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