| 1. |
- Svensäter, Gunnel, et al.
(författare)
-
Risk, riskbedömning och prevention
- 2008
-
Ingår i: Tandläkartidningen. - 0039-6982. ; 100:9-10, s. 70-76
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Biologiska markörer som baserar sig på egenskaper och aktivitet hos bakterier i dentala biofilmer skulle kunna användas för att identifiera patienter med hög risk för karies och parodontit. Genom att studera hur tandläkare gör riskbedömningar och tar beslut om åtgärder kan man få ett bra underlag för att förbättra praxis.
|
|
| 2. |
|
|
| 3. |
- Chávez de Paz, Luis Eduardo, et al.
(författare)
-
Oral bacteria in biofilms exhibit slow reactivation from nutrient deprivation
- 2008
-
Ingår i: Microbiology. - : Microbiology Society. - 1350-0872 .- 1465-2080. ; 154, s. 1927-1938
-
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.
|
|
| 4. |
- Chávez de Paz, Luis Eduardo, et al.
(författare)
-
Response to alkaline stress by root canal bacteria in biofilms
- 2007
-
Ingår i: International Endodontic Journal. - : Wiley. - 0143-2885 .- 1365-2591. ; 40:5, s. 344-355
-
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.
|
|
| 5. |
|
|
| 6. |
- Davies, Julia, et al.
(författare)
-
Identification of novel LPXTG-linked surface proteins from Streptococcus gordonii
- 2009
-
Ingår i: Microbiology. - : Microbiology Society. - 1350-0872 .- 1465-2080. ; 155, s. 1977-1988
-
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.
|
|
| 7. |
|
|
| 8. |
- Eriksen, Harald M, et al.
(författare)
-
The oral ecosystem : implications for education
- 2006
-
Ingår i: European journal of dental education. - : Wiley. - 1396-5883 .- 1600-0579. ; 10:4, s. 192-196
-
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.
|
|
| 9. |
- Kinnby, Bertil, et al.
(författare)
-
Plasminogen binding by oral streptococci from dental plaque and inflammatory lesions
- 2008
-
Ingår i: Microbiology. - : Microbiology Society. - 1350-0872 .- 1465-2080. ; 154:3, s. 924-931
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Plasminogen binding by bacteria is a virulence factor important for the entry and dissemination of bacteria in the body. A wide variety of bacteria bind plasminogen, including both organisms causing disease and components of the normal oral flora. The purpose of this study was to examine the characteristics of plasminogen binding by six clinical isolates of oral streptococci from both dental plaque and inflammatory lesions. All the strains bound plasminogen with approximately the same affinity, and binding was specific and lysine-dependent as evidenced by its inhibition by epsilon-aminocaproic acid. All of the test strains were capable of activating bound plasminogen to plasmin without the addition of a plasminogen activator, and subsequent analysis revealed the presence of streptokinase in all strains. However, the streptococci exhibited fibrinolytic activity only in the presence of plasminogen and this could be inhibited by the addition of epsilon-aminocaproic acid. SDS-PAGE and 2D gel electrophoresis coupled with plasminogen ligand blotting showed that only a subset of the total proteins (2-15) were involved in the binding of plasminogen. Partial identification of the binding proteins revealed that four glycolytic enzymes, enolase, phosphoglycerate kinase, glyceraldehyde-3-phosphate dehydrogenase and phosphoglycerate mutase, were predominant in binding plasminogen. The binding of plasminogen by bacteria from pus did not differ from that of the strains from supragingival plaque. The findings illustrate how apparently innocuous commensal bacteria are capable of utilizing a mechanism that is generally regarded as being of importance to pathogenicity and suggest an additional role of plasminogen binding.
|
|
| 10. |
- Lager, Anders, et al.
(författare)
-
Microbiota in dentine caries cultivable on pH-selective agars
- 2008
-
Konferensbidrag (refereegranskat)abstract
- Objective: To investigate the acid tolerant microflora at different levels in established dentine caries lesions using solid pH-selective media, as acid stress might be a major selective determinant in dentine caries ecosystems. Methods: Primary dentine caries lesions (vital teeth, no symptoms) in five patients were sampled aseptically with a rose-bur at three levels: superficially, in the centre and the bottom of the lesion, when it was considered clinically caries free using visual and tactile criteria. Samples were incubated on neutral (blood agar) and pH-selective (Todd-Hewitt agar buffered to pH 4.0, 4.5, 5.0, 5.5) agar. Numbers of colony-forming units (cfu) were determined and colonies were characterized morphologically and with enzymatic- and sugar fermentation tests. Results: The total numbers of bacteria recovered from the pH-neutral agars did not decrease significantly with lesion depth (median blood agar: 6.3×103 superficially; 2.2×103 bottom) whereas cfu recovery from low pH agars decreased with increasing agar acidity. The composition of the aciduric microflora varied both between subjects and between sample sites within the lesions. Gram-positive cocci were most abundant, but with lower pH and deeper sampling sites, the numbers of lactobacilli and other Gram-positive rods increased. Mutans streptococci were found at all sampling depths. S. anginosus, S. constellatus, S. crista, S. gordonii, S. intermedius and S. sanguis were found less frequently. Conclusions: The study clearly indicates that many different microorganisms can be recovered on pH 5.5 agars and thus survive in low pH environments. pH 5.5 is quite sufficient to moderately demineralize dentine, and aciduric microorganisms should thus have the potential to contribute to the dentine caries process. Approved by the ethical committee at Lund University. Funded by Faculty grants.
|
|
