| 1. |
- Chávez de Paz, Luis, 1974, et al.
(författare)
-
Gram-positive rods prevailing in teeth with apical periodontitis undergoing root canal treatment.
- 2004
-
Ingår i: International endodontic journal. - : Wiley. - 0143-2885 .- 1365-2591. ; 37:9, s. 579-87
-
Tidskriftsartikel (refereegranskat)abstract
- AIMS: To identify Gram-positive rods from root canals of teeth with apical periodontitis and to examine their associations with other species. METHODOLOGY: Consecutive root canal samples (RCSs) from 139 teeth undergoing root canal treatment were analyzed prospectively for cultivable microbes. Gram-positive rods in the first RCS submitted after chemo-mechanical preparation were categorised to genus level by selective media and gas-liquid chromatography (GLC), and identified to species level by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Associations between organisms were measured by odds ratios (OR). RESULTS: In the first samples submitted a total of 158 Gram-positive rods, 115 Gram-positive cocci, 26 Gram-negative rods and 9 Gram-negative cocci, were identified. At genus levels Gram-positive rods were classified into: Lactobacillus spp. (38%), Olsenella spp. (18%), Propionibacterium spp. (13%), Actinomyces spp. (12%), Bifidobacterium spp. (13%) and Eubacterium spp. (6%). The most frequent species were Olsenella uli, Lactobacillus paracasei and Propionibacterium propionicum. In subsequent samples taken during treatment, Gram-positive rods were also identified, although the number of strains was considerably reduced. Positive associations were observed between members of the genus lactobacilli and Gram-positive cocci (OR>2). CONCLUSIONS: Olsenella uli and Lactobacillus spp. predominated over other Gram-positive rods. A possible association exists between Lactobacillus spp. and Gram-positive cocci in root canals of teeth with apical periodontitis receiving treatment.
|
|
| 2. |
- Chávez de Paz, Luis, 1974
(författare)
-
On bacteria Persisting Root Canal Treament. Identification and potential mechanisms of resistance to antimicrobial measures.
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Anti-microbial treatment of infected root canals using mechanical instrumentation and chemicals for disinfection does not always lead to complete bacterial elimination and treatment failure may therefore result. As certain bacteria appear more resilient to endodontic treatment than others, the present thesis addresses the species that can most frequently be isolated after treatment and explores mechanisms, which could potentially afford these organisms resistance to anti-microbial treatment measures.In an initial assessment, consecutive root canal samples from a total of 200 clinical cases were analysed for cultivable microbes. Patients had present with clinical and/or radiographic evidence of apical periodontitis. Root canal treatment had been initiated at one or more appointments prior to sampling. Results demonstrated a clear predominance of Gram-positive rods and cocci. These organisms outweighed other bacterial groups common in primary root canal infections including Gram-negative anaerobes.In a second study, a protocol for identification of Gram-positive rods at the species level was validated. Here, 86 cases presenting with Gram-positive rods in the first study as well as 53 new cases were included. Identification was based on a combination of selective media, gas-liquid chromatography and SDS-PAGE electrophoresis of whole-cell proteins. Of a total of 158 Gram-positive rods isolated, it was possible to identify 96% at the species level. The most common species were Olsenella uli, Lactobacillus paracasei and Propionibacterium propionicum.In a third study Streptococcus, being the second largest group of organisms isolated in the first study, were subjected to identification. Extra-cellular proteins produced in culture media were also screened. A total of 100 cases (45 from study I, 32 from study II and 23 new cases), which showed growth of streptococcal species were included. Criteria for identification were based on physiological characteristics. The most frequently isolated species were Streptococcus gordonii, Streptococcus anginosus and Streptococcus oralis. The protein release pattern expressed by clinical isolates was different from that of corresponding laboratory strains. S. gordonii, S. anginosus, S. oralis and S. parasanguis produced the molecular chaperone. DnaK extra-cellularly. The bacterial cell viability and protein response patterns to alkaline stress of collection of seven organisms, isolated in the previous studies, were assessed in paper IV. When tested under planktonic growth conditions, cells were found to be less viable after an alkaline challenge than corresponding cells growing in biofilms. Excretion of proteins appeared to be a rapid response of these organisms prior to a switch stationary phase. When these strains were grown in mixed cultures (community assessments - unpublished data), viability of cells seemed to be less affected by alkaline challenge. In addition, the rate at which bacteria switched into an inactive phase appeared to increased.In conclusion, Gram-positive rods and cocci seem to be the most enduring organisms in infected root canals subjected to endodontic treatment. The formation of biofilms and expression of a variety of proteins, as well as growth in mixed communities, may provide these organisms with the capacity to resist root canal treatment.
|
|
| 3. |
- Chávez de Paz, Luis, 1974, et al.
(författare)
-
Response to alkaline stress by root canal bacteria in biofilms. : Viability and mechanisms of response to alkaline stress by selected root canal bacteria.
- 2007
-
Ingår i: International endodontic journal. - : Wiley. - 0143-2885 .- 1365-2591. ; 40:5, s. 344-55
-
Tidskriftsartikel (refereegranskat)abstract
- AIM: 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.
|
|
| 4. |
- Chávez de Paz, Luis, 1974, et al.
(författare)
-
Streptococci from root canals in teeth with apical periodontitis receiving endodontic treatment.
- 2005
-
Ingår i: Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics. - : Elsevier BV. - 1528-395X .- 1079-2104. ; 100:2, s. 232-41
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: The object of this study was to investigate the diversity among streptococcal species isolated from root canals in conjunction with endodontic therapy and to characterize their production of extracellular proteins. STUDY DESIGN: Consecutive root canal samples (RCS) taken as bacteriological controls during root canal treatment of teeth with apical periodontitis were analyzed in a total of 100 clinical cases. Bacteria were isolated and classified by selective media and gas liquid chromatography. Streptococcal strains were identified by carbohydrate fermentation, hydrolysis of aesculin/arginine, and production of enzymes. Releases of extracellular proteins by streptococci and Enterococcus spp in fluid culture media were examined with SDS-PAGE and 2-dimension gel electrophoresis (2 DE). Extracellular proteins produced were quantified and qualitatively analyzed. Specific proteins were targeted with Western immunoblot assays. Comparisons were made with type strains. RESULTS: Of a total of 241 bacterial strains recovered in the first samples submitted, Streptococcus gordonii, S anginosus, and S oralis were the most frequently isolated streptococci. In 49 of 89 resubmitted samples showing bacterial growth, S gordonii and S oralis still predominated among streptococci. Other common bacterial isolates were Enterococcus spp, Lactobacillus paracasei, and Olsenella uli. Quantitative and qualitative differences in extracellular protein production were observed among clinical isolates and laboratory streptococcal strains. In similar conditions for growth, S intermedius, S anginosus, S oralis, and S gordonii were strong producers of extracellular proteins (>3.0 microg/mL), while Enterococcus spp and S mutans were weak. Whole cell protein extracts showed a different profile from that of extracellular proteins. The chaperone protein DnaK was recognized to be produced extracellularly by S gordonii, S oralis, S anginosus, and S parasanguis. CONCLUSIONS: Being strong producers of extracellular proteins and by virtue of common presence in teeth undergoing endodontic therapy, S gordonii, S anginosus, and S oralis may be of pathogenic significance in posttreatment apical periodontitis.
|
|
| 5. |
- Dahlén, Gunnar, 1944, et al.
(författare)
-
Microbiology and Immunology of endodontic infections
- 2017
-
Ingår i: Endodontic prognosis. Chugal N., Lin L. (eds). - Cham : Springer. - 9783319424125 ; , s. 13-27
-
Bokkapitel (refereegranskat)abstract
- Endodontic infections are complex diseases associated with apical tissue inflammation that is determined by microbial, immunological, and environmental factors. During the past years, the integration of research tools, including molecular techniques for identification, sophisticated in vitro modeling, and human microbiome analysis, has provided additional insight in the understanding of endodontic infections. Recent studies suggest that the basis for infections associated to root canals of teeth is polymicrobial in nature and includes the emergence of microbial colonization in form of biofilms. Biofilms deep seated in areas that are difficult to reach by mechanical treatment will enhance microbial virulence, antibiotic resistance, colonization potential, and resistance. Furthermore, with the advent of the human oral microbiome project, insights on the differences among oral microfloras in different individuals appear to have an important role in progressing endodontic infections. This chapter discusses the current data regarding the role that microbial biofilms play in endodontic infections, as well as its place in the current knowledge of endodontic microbiology. The complex relations between the root canal microflora and the inflammatory response in apical periodontitis are also highlighted in this chapter, as well as their implications in regard to the diagnosis and clinical management of endodontic infections.
|
|
| 6. |
- Fröjd, Victoria, 1986, et al.
(författare)
-
Effect of nanoporous TiO2 coating and anodized Ca2+ modification of titanium surfaces on early microbial biofilm formation.
- 2011
-
Ingår i: BMC oral health. - London, UK : Springer Science and Business Media LLC. - 1472-6831. ; 11
-
Tidskriftsartikel (refereegranskat)abstract
- The soft tissue around dental implants forms a barrier between the oral environment and the peri-implant bone and a crucial factor for long-term success of therapy is development of a good abutment/soft-tissue seal. Sol-gel derived nanoporous TiO2 coatings have been shown to enhance soft-tissue attachment but their effect on adhesion and biofilm formation by oral bacteria is unknown.
|
|
| 7. |
- Fröjd, Victoria, 1986, et al.
(författare)
-
In situ analysis of multispecies biofilm formation on customized titanium surfaces
- 2011
-
Ingår i: Molecular Oral Microbiology. - : John Wiley & Sons. - 2041-1006 .- 2041-1014. ; 26:4, s. 241-252
-
Tidskriftsartikel (refereegranskat)abstract
- Many studies to identify surfaces that enhance the incorporation of dental implants into bone and soft-tissue have been undertaken previously. However, to succeed in the clinical situation, an implant surface must not support development of microbial biofilms with a pathogenic potential. As a first step in investigating this, we used two-species and three-species biofilm models with 16S ribosomal RNA fluorescence in situ hybridization and confocal laser scanning microscopy to examine the effect of surface characteristics on biofilm formation by species that can colonize titanium implants in vivo: Streptococcus sanguinis, Actinomyces naeslundii and Lactobacillus salivarius. Surfaces blasted with Al(2) O(3) (S(a) = 1.0-2.0 μm) showed a seven-fold higher bacterial adhesion after 2 h than turned surfaces (S(a) = 0.18 μm) whereas porous surfaces, generated by anodic oxidation (S(a) = 0.4 μm), showed four-fold greater adhesion than turned surfaces. Hence, increased roughness promoted adhesion, most likely through protection of bacteria from shear forces. Chemical modification of the blasted and oxidized surfaces by incorporation of Ca(2+) ions reduced adhesion compared with the corresponding non-modified surfaces. After 14 h, biofilm growth occurred in the three-species model but not in the two-species consortium (containing S. sanguinis and A. naeslundii only). The biofilm biovolume on all surfaces was similar, suggesting that the influence of surface characteristics on adhesion was compensated for by biofilm development.
|
|
