Britta Kleine

Ruhr-Universität Bochum, Bochum, North Rhine-Westphalia, Germany

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Publications (10)22.76 Total impact

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    ABSTRACT: Staphylococcal lipases have been proposed as pathogenicity factors. In Staphylococcus saprophyticus the surface-associated protein (Ssp) has been previously characterized as a cell wall-associated true lipase. A S. saprophyticus Δssp::ermB mutant has been described as less virulent in an in vivo model of urinary tract infection compared with its wild-type. This is the first report showing that S. saprophyticus induced a lifespan reduction in Caenorhabditis elegans similar to that of S. aureus RN4220. In two S. saprophyticus Δssp::ermB mutants lifespan reduction in C. elegans was partly abolished. In order to attribute virulence to the lipase activity itself and distinguish this phenomenon from the presence of the Ssp-protein, the conserved active site of the lipase was modified by site-directed ligase-independent mutagenesis and lipase activity-deficient mutants were constructed. These results indicate that the Ssp is associated with pathogenicity in C. elegans and one could speculate that the lipase activity itself is responsible for this virulence.
    Virulence 08/2013; 4(7). · 2.79 Impact Factor
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    ABSTRACT: The main aim of this study was to examine the genotypic and phenotypic diversity of Staphylococcus saprophyticus isolates from human and animal origin. In total, 236 clinical isolates and 15 animal isolates of S. saprophyticus were characterized in respect of the occurrence of 9 potential virulence genes and four surface properties. All strains were PCR positive for the regulatory genes agr, sar >it>A and rot as well as for the surface proteins UafA and Aas. Nearly 90% of the clinical isolates were found to possess the gene for the surface-associated lipase Ssp and 10% for the collagen binding MSCRAMM SdrI. All animal isolates were negative forsdrI. Lipolytic activity could be detected in 66% of the clinical and 46% of the animal isolates. Adherence to collagen type I was shown of 20% of the clinical strains and 6% of the strains of animal origin. Most S. saprophyticus strains showed hydrophobic properties and only few could agglutinate sheep erythrocytes. We described a broad analysis of animal and human S. saprophyticus isolates regarding virulence genes and phenotypic properties such as lipase activity, hydrophobicity, and adherence. While S. saprophyticus strains from animal sources have prerequisites for colonization of the urinary tract like the D-serine-deaminase, out findings suggested that they need to acquire new genes e.g. MSCRAMMS for adherence like sdrI and to modulate their existing properties e.g. increasing the lipase activity or reducing hydrophobicity. These apparently important new genes or properties for virulence have to be further analyzed.
    BMC Research Notes 01/2010; 3:163.
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    ABSTRACT: Human urine contains a relatively high concentration of d-serine, which is toxic to several nonuropathogenic bacteria, but can be utilized or detoxified by uropathogenic Escherichia coli (UPEC). The sequenced genome of uropathogenic Staphylococcus saprophyticus contains a gene with homology to the d-serine deaminase gene (dsdA) of UPEC. We found the gene in several clinical isolates of S. saprophyticus; however, the gene was absent in Staphylococcus xylosus and Staphylococcus cohnii, phylogenetically close relatives of S. saprophyticus, and could also not be detected in isolates of Staphylococcus aureus, Staphylococcus epidermidis and 13 other staphylococcal species. In addition, the genomes of other sequenced staphylococci do not harbor homologues of this operon. Interestingly, S. saprophyticus could grow in media supplemented with relatively high concentrations of d-serine, whereas S. aureus, S. epidermidis and other staphylococcal species could not. The association of the dsdA gene with growth in media including d-serine was proved by introducing the gene into S. aureus Newman. Given the fact that UPEC and S. saprophyticus tolerate this compound, d-serine utilization and detoxification may be a general property of uropathogenic bacteria.
    FEMS Microbiology Letters 09/2009; 299(1):60-4. · 2.05 Impact Factor
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    ABSTRACT: Staphylococcus saprophyticus, an important cause of urinary tract infections in young women, expresses the surface protein SdrI, a member of the serine-aspartate repeat (SD) protein family. Here we analyse the fibronectin-binding ability of SdrI, as S. saprophyticus is known to bind fibronectin and there is no known SD protein with this function. This protein does not contain the binding motif typical for fibronectin-binding proteins. Using recombinant fragments of SdrI, we localized the binding domain in the A region and show that SdrI bound to the N-terminal 30-kDa fragment of fibronectin. The fibronectin-binding function was shown in the natural host using an SdrI knockout mutant that showed decreased binding to fibronectin compared with wild-type strain 7108.
    FEMS Microbiology Letters 09/2009; 301(1):28-34. · 2.05 Impact Factor
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    Veterinary Microbiology 07/2009; 139(3-4):417-8. · 3.13 Impact Factor
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    ABSTRACT: Background: Therapeutic options in enterobacteriaceae are limited due to an increasing prevalence of quinolone resistance and of extended spectrum beta-lactamases (ESBL). Apart from mutations in DNA gyrase and topoisomerase IV, quinolone resistance can also be caused by plasmid-mediated mechanisms. Whereas qnr genes are known for almost ten years, a variant of an aminoglycoside-modifying enzyme, aac(6')-Ib-cr, and and a quinolone efflux pump gene, qepA, have been described only recently. As data from Germany about the latter two genes are absent, we performed a study to determine the prevalence of plasmid-mediated quinolone resistance determinants in ESBL isolates from our area. Methods: ESBL producing E. coli and K. pneumoniae isolates from two departments located in different hospitals were collected in 2006 and 2007. Genes coding for qnrA, qnrB, qnrS, qepA and aac(6')-Ib were detected by PCR; aac(6')-Ib-cr was further identified by digestion with BstF5I. Results: Of 102 ESBL E. coli isolates qnrA was identified in three isolates, qnrS in one isolate and aac(6')-Ib-cr in 49 isolates (48%). Of 75 ESBL K. pneumoniae isolates qnrA was found in two isolates, qnrS in one isolate and aac(6')-Ib-cr in 39 isolates (52%). qnrB and qepA were not found in any isolate. Conclusion: The prevalence of qnr genes was low in ESBL isolates of E. coli and K. pneumoniae of our area and qepA was not identified at all. However, for the first time a high prevalence of aac(6')-Ib-cr, which confers resistance to tobramycin and ciprofloxacin, could be described in ESBL isolates from Germany.
    Infectious Diseases Society of America 2008 Annual Meeting; 10/2008
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    ABSTRACT: Invasion of bacteria into nonphagocytic host cells is an important pathogenicity factor for escaping the host defence system. Gram-positive organisms, for example Staphylococcus aureus and Listeria monocytogenes, are invasive in nonphagocytic cells, and this mechanism is discussed as an important part of the infection process. Uropathogenic Escherichia coli and Staphylococcus saprophyticus can cause acute and recurrent urinary tract infections as well as bloodstream infections. Staphylococcus saprophyticus shows strong adhesion to human urinary bladder carcinoma and Hep2 cells and expresses the 'Microbial Surface Components Recognizing Adhesive Matrix molecule' (MSCRAMM)-protein SdrI with collagen-binding activity. MSCRAMMs are responsible for adhesion and collagen binding in S. aureus and are discussed as an important pathogenicity factor for invasion. To investigate internalization in S. aureus, several fluorescence activated cell sorting (FACS) assays have been described recently. We used a previously described FACS assay, with slight modifications, in addition to an antibiotic protection assay and transmission electron microscopy to show that S. saprophyticus ATCC 15305 and the wild-type strain 7108 were internalized into the human urinary bladder carcinoma cell line 5637. The discovery of the internalization of S. saprophyticus may be an important step for understanding the pathogenicity of recurrent infections caused by this organism.
    FEMS Microbiology Letters 07/2008; 285(2):163-9. · 2.05 Impact Factor
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    ABSTRACT: Penicillinase testing is required for Staphylococcus aureus isolates with a penicillin MIC of </=0.12 mg/L. This study compared five phenotypic assays with a PCR for blaZ when testing 197 S. aureus isolates. The starch-iodine plate method and nitrocefin tests had low sensitivities of 42.9% and 35.7%, respectively. The cloverleaf assay and the penicillin zone-edge determination method had sensitivities of 67.8% and 71.4%, respectively, and these methods might be appropriate in many circumstances, but were not as sensitive as blaZ PCR.
    Clinical Microbiology and Infection 06/2008; 14(6):614-6. · 4.58 Impact Factor
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    ABSTRACT: Staphylococcus saprophyticus, an important cause of urinary tract infections, produces a surface-associated lipase, Ssp. In contrast to other lipases, Ssp is a protein that is present in high amounts on the surface of the bacteria and it was shown that it is a true lipase. Characterization of S. saprophyticus lipase (Ssp) showed that it is more similar to Staphylococcus aureus lipase and Staphylococcus epidermidis lipase than to Staphylococcus hyicus lipase and Staphylococcus simulans lipase. Ssp showed an optimum of lipolytic activity at pH 6 and lost its activity at pH>8 or pH<5. The present results show that Ssp activity is dependent on Ca(2+). Consequently, activity increased c. 10-fold in the presence of 2 mM Ca(2+). Optimal activity was reached at 30 degrees C. It was also observed that the enzymatic activity of Ssp depends strongly on the acyl chain length of the substrate molecule.
    FEMS Microbiology Letters 10/2007; 274(2):335-41. · 2.05 Impact Factor
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    ABSTRACT: A gene encoding a serine-aspartate repeat protein of Staphylococcus saprophyticus, an important cause of urinary tract infections in young women, has been cloned and sequenced. In contrast to other SD repeat proteins, SdrI carries 21 additional N-terminal repeats with a consensus sequence of (P/A)ATKE(K/E)A(A/V)(T/I)(A/T/S)EE and has the longest SD(AD)(1-5) repetitive region (854 amino acids) described so far. This highly repetitive sequence contains only the amino acids serine, asparagine, and a distinctly greater amount of alanine (37%) than all other known SD repeat proteins (2.3 to 4.4%). In addition, it is a collagen-binding protein of S. saprophyticus and the second example in this organism of a surface protein carrying the LPXTG motif. We constructed an isogenic sdrI knockout mutant that showed decreased binding to immobilized collagen compared with wild-type S. saprophyticus strain 7108. Binding could be reconstituted by complementation. Collagen binding is specifically caused by SdrI, and the recently described UafA protein, the only LPXTG-containing protein in the genome sequence of the type strain, is not involved in this trait. Our experiments suggest that, as in other staphylococci, the presence of different LPXTG-anchored cell wall proteins is common in S. saprophyticus and support the notion that the presence of matrix-binding surface proteins is common in staphylococci.
    Infection and Immunity 09/2006; 74(8):4615-23. · 4.07 Impact Factor