| 1. |
- Pihl, Maria, et al.
(författare)
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Bacteria on catheters in patients undergoing peritoneal dialysis
- 2013
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Ingår i: Peritoneal Dialysis International. - Multimed Inc.. - 0896-8608. ; 33:1, s. 51-59
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Tidskriftsartikel (refereegranskat)abstract
- Background: Peritonitis is the leading cause of morbidity for peritoneal dialysis (PD) patients, and microbial biofilms have previously been identified on catheters from infected patients. However, few studies of catheters from patients without clinical signs of infection have been undertaken. The aim of the present study was to investigate the extent to which bacteria are present on catheters from PD patients with no symptoms of infection. Methods: Microbiologic culturing under aerobic and anaerobic conditions and confocal laser scanning microscopy were used to determine the distribution of bacteria on PD catheters from 15 patients without clinical signs of infection and on catheters from 2 infected patients. The 16S rRNA gene sequencing technique was used to identify cultured bacteria.. Results: Bacteria were detected on 12 of the 15 catheters from patients without signs of infection and on the 2 catheters from infected patients. Single-species and mixed-microbial communities containing up to 5 species were present on both the inside and the outside along the whole length of the colonized catheters. The bacterial species most commonly found were the skin commensals Staphylococcus epidermidis and Propionibacterium acnes, followed by S. warneri and S. lugdunensis. The strains of these micro-organisms, particularly those of S. epidermidis, varied in phenotype with respect to their tolerance of the major classes of antibiotics. Conclusions: Bacteria were common on catheters from patients without symptoms of infection. Up to 4 different bacterial species were found in close association and may represent a risk factor for the future development of peritonitis in patients hosting such micro-organisms. Perit Dial Int 2013; 33(1):51-59 www.PDIConnect.com epub ahead of print: 01 Aug 2012 doi:10.3747/pdi.2011.00320
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| 2. |
- Wickström, Claes, et al.
(författare)
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Proteolytic degradation of human salivary MUC5B by dental biofilms.
- 2009
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Ingår i: Microbiology (Reading, England). - 1350-0872. ; :Jun 25
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Tidskriftsartikel (refereegranskat)abstract
- The degradation of complex substrates, like salivary mucins, requires an arsenal of glycosidases and proteases to sequentially degrade the oligosaccharides and polypeptide backbone. MUC5B is a complex oligomeric glycoprotein, heterogeneous in molecular mass (14-40 x 106 Da), with a diverse repertoire of oligosaccharides, differing in composition and charge. The aim of this study was to investigate whether proteolytic degradation of the mucin polypeptide backbone could be identified and if cooperation of dental biofilm bacteria was required. Cooperative bacterial-mediated proteolysis of MUC5B was determined by comparing individual and mixed consortia of strains isolated from supragingival plaque and freshly harvested supragingival plaque. Proteolytic activity was analyzed using fluorescent labelled substrate and by visualizing mucin degradation by SDS-PAGE. Dental plaque degraded the polypeptide backbone of the salivary MUC5B mucin. The mucin also was degraded by a specific consortium of isolated species from supragingival plaque, although individual species and other consortia did not. Select bacteria in supragingival dental plaque, therefore, cooperate as a consortium to proteolyze human salivary MUC5B and hydrolyze glycosides.
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| 3. |
- Chávez de Paz, Luis E, et al.
(författare)
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Oral bacteria in biofilms exhibit slow reactivation from nutrient deprivation
- 2008
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Ingår i: Microbiology. - 1350-0872. ; 154, s. 1927-38
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Tidskriftsartikel (refereegranskat)abstract
- The ability of oral bacteria to enter a non-growing state is believed to be an important mechanism for survival in the starved micro-environments of the oral cavity. In this study, we examined the reactivation of nutrient-deprived cells of two oral bacteria in biofilms, Streptococcus anginosus and Lactobacillus salivarius. Non-growing cells were generated by incubation in 10 mM potassium phosphate buffer for 24 h and the results were compared to those of planktonic cultures. When both types of cells were shifted from a rich, peptone-yeast extract-glucose (PYG) medium to buffer for 24 h, dehydrogenase and esterase activity measured by the fluorescent dyes 5-cyano-2,3-ditolyl-tetrazolium chloride (CTC) and fluorescein diacetate (FDA), respectively, was absent in both species. However, the membranes of the vast majority of nutrient-deprived cells remained intact as assessed by LIVE/DEAD staining. Metabolic reactivation of the nutrient-deprived biofilm cells was not observed for at least 48 h following addition of fresh PYG medium, whereas the non-growing planktonic cultures of the same two strains were in rapid growth in less than 2 h. At 72 h, the S. anginosus biofilm cells had recovered 78 % of the dehydrogenase activity and 61 % of the esterase activity and the biomass mm(-2) had increased by 30-35 %. With L. salivarius at 72 h, the biofilms had recovered 56 % and 75 % of dehydrogenase and esterase activity, respectively. Reactivation of both species in biofilms was enhanced by removal of glucose from PYG, and S. anginosus cells were particularly responsive to yeast extract (YE) medium. The data suggest that the low reactivity of non-growing biofilm cells to the introduction of fresh nutrients may be a survival strategy employed by micro-organisms in the oral cavity.
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| 4. |
- Chávez de Paz, Luis E, et al.
(författare)
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Response to alkaline stress by root canal bacteria in biofilms.
- 2007
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Ingår i: International endodontic journal. - 0143-2885. ; 40:5, s. 344-55
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Tidskriftsartikel (refereegranskat)abstract
- To determine whether bacteria isolated from infected root canals survive alkaline shifts better in biofilms than in planktonic cultures. METHODOLOGY: Clinical isolates of Enterococcus faecalis, Lactobacillus paracasei, Olsenella uli, Streptococcus anginosus, S. gordonii, S. oralis and Fusobacterium nucleatum in biofilm and planktonic cultures were stressed at pH 10.5 for 4 h, and cell viability determined using the fluorescent staining LIVE/DEAD BacLight bacterial viability kit. In addition, proteins released into extracellular culture fluids were identified by Western blotting. RESULTS: Enterococcus faecalis, L. paracasei, O. uli and S. gordonii survived in high numbers in both planktonic cultures and in biofilms after alkaline challenge. S. anginosus, S. oralis and F. nucleatum showed increased viability in biofilms compared with planktonic cultures. Alkaline exposure caused all planktonic cultures to aggregate into clusters and resulted in a greater extrusion of cellular proteins compared with cells in biofilms. Increased levels of DnaK, HPr and fructose-1,6-bisphosphate aldolase were observed in culture fluids, especially amongst streptococci. CONCLUSIONS: In general, bacteria isolated from infected roots canals resisted alkaline stress better in biofilms than in planktonic cultures, however, planktonic cells appeared to use aggregation and the extracellular transport of specific proteins as survival mechanisms.
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| 5. |
- Chávez de Paz, Luis, et al.
(författare)
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The effects of antimicrobials on endodontic biofilm bacteria
- 2010
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Ingår i: Journal of Endodontics;1. - Elsevier. - 1878-3554. ; 36:1, s. 70-77
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Tidskriftsartikel (refereegranskat)abstract
- Introduction In the present study, confocal microscopy, a miniflow cell system, and image analysis were combined to test in situ the effect of antimicrobials and alkali on biofilms of Enterococcus faecalis, Lactobacillus paracasei, Streptococcus anginosus, and Streptococcus gordonii isolated from root canals with persistent infections. Methods Biofilms formed for 24 hours were exposed for 5 minutes to alkali (pH = 12), chlorhexidine digluconate (2.5%), EDTA (50 mmol/L), and sodium hypochlorite (1%). The biofilms were then characterized by using fluorescent markers targeting cell membrane integrity (LIVE/DEAD) and metabolic activity (5-cyano-2,3-ditolyl tetrazolium chloride and fluorescein diacetate). In addition, the biofilm architecture and the extent to which coating of the substrate surface with collagen influenced the resistance pattern to the chemicals were also analyzed. Results NaOCl (1%) affected the membrane integrity of all organisms and removed most biofilm cells. Exposure to EDTA (50 mmol/L) affected the membrane integrity in all organisms but failed to remove more than a few cells in biofilms of E. faecalis, L. paracasei, and S. anginosus. Chlorhexidine (2.5%) had a mild effect on the membrane integrity of E. faecalis and removed only 50% of its biofilm cells The effects were substratum-dependent, and most organisms displayed increased resistance to the antimicrobials on collagen-coated surfaces. Conclusions The biofilm system developed here was sensitive and differences in cell membrane integrity and removal of biofilm cells after exposure to antimicrobials commonly used in endodontics was discernible.
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| 6. |
- Dahlén, Gunnar, 1944-, et al.
(författare)
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Risk, riskbedömning och prevention
- 2008
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Ingår i: Tandläkartidningen;9-10. - 0039-6982. ; 100:9-10, s. 70-6
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 7. |
- Davies, Julia, et al.
(författare)
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Identification of novel LPXTG-linked surface proteins from Streptococcus gordonii
- 2009
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Ingår i: Microbiology. - 1350-0872. ; 155, s. 1977-1988
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Tidskriftsartikel (refereegranskat)abstract
- Surface adhesion plays an essential part in the survival of the commensal organism Streptococcus gordonii in the oral cavity as well as during opportunistic infections such as endocarditis. At least two types of cell surface protein involved in adhesion are found on the surface of Gram-positive bacteria: those anchored via an LPXTG motif by the enzyme sortase A (SrtA) and those associated with the cell surface by, as yet, unknown mechanisms. In srtA(-) mutants, LPXTG-containing proteins have been shown to be released rather than cross-linked to the cell wall. We have therefore used 2D gel electrophoresis of released proteins from an srtA(-) mutant as well as the wild-type strain, followed by peptide identification by MS, to identify a set of novel proteins predicted to be present on the surface of S. gordonii DL1. This includes two large LPXTG-linked proteins (SGO_0707 and SGO_1487), which both contain tandemly repeated sequences similar to those present in known fibrillar adhesins. A 5'-nucleotidase and a protein with a putative collagen-binding domain, both containing LPXTG motifs, were also identified. Anchorless proteins with known chaperone, stress response and elongation factor functions, apparently responsible for bacterial binding to keratinocytes and saliva-coated surfaces in the absence of the LPXTG-linked adhesins, were also associated with the cell surface. These data reveal a range of proteins to be present on the S. gordonii DL1 cell surface, the expression of which plays an important role in adhesion to epithelia and which represent likely candidates for novel virulence factors in S. gordonii.
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| 8. |
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| 9. |
- Dorkhan, Marjan, et al.
(författare)
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Effects of saliva or serum coating on adherence of Streptococcus oralis strains to titanium
- 2012
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Ingår i: Microbiology;2. - Society for General Microbiology. - 1350-0872. ; 158:2, s. 390-397
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Tidskriftsartikel (refereegranskat)abstract
- The use of dental implants to treat tooth loss has increased rapidly over recent years. 'Smooth' implants showing high long-term success rates have successively been replaced by implants with rougher surfaces, designed to stimulate rapid osseointegration and promote tissue healing. If exposed in the oral cavity, rougher surfaces may promote bacterial adhesion leading to formation of microbial biofilms which can induce peri-implant inflammation. Streptococcus oralis is an early colonizer of oral surfaces and has been recovered from titanium surfaces in vivo. The purpose of this study was to examine the adherence of clinical strains of S. oralis to titanium with smooth or moderately rough surface topography and to determine the effect of a saliva- or serum-derived coating on this process. Adherence was studied using a flow-cell system with confocal laser scanning microscopy, while putative adhesins were analysed using proteomics of bacterial cell wall proteins. This showed that adherence to moderately rough was greater than to smooth surfaces. Serum did not promote binding of any studied S. oralis strains to titanium whereas a saliva-coating increased adherence in two of three strains tested. The high level of adherence to the moderately rough surfaces was maintained even in the presence of a saliva coating. The S. oralis strains that bound to saliva expressed an LPXTG-linked protein which was not present in the non-adherent strain. Thus strains of S. oralis differ in their capacity to bind to saliva-coated titanium and we propose that this is due to differential expression of a novel adhesin.
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| 10. |
- Eriksen, Harald M, et al.
(författare)
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The oral ecosystem: implications for education
- 2006
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Ingår i: European journal of dental education;4. - 1396-5883. ; 10:4, s. 192-6
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Tidskriftsartikel (refereegranskat)abstract
- We propose a model that is applicable to oral health education. The model describes the oral cavity in a complexity-based ecological context. This concept includes the premise that factors from different organisational levels (biological, individual, community, society) interact in a complex way with the potential to 'stress' the ecosystem and thereby provoke changes. This mode of action complies with the understanding of the oral cavity as a complex adaptive system. An ecological model is actively used in the undergraduate problem-based curriculum at the Faculty of Odontology, Malmo University, Sweden and has recently been applied as a conceptual basis for the new dental curriculum being established at the University of Tromso in Northern Norway. The purpose is to encourage and promote an ecological, health-oriented view and to stimulate reflections on premises for oral health and diseases in an integrated context.
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