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- Chávez de Paz, Luis, 1974, et al.
(författare)
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Response to alkaline stress by root canal bacteria in biofilms. : Viability and mechanisms of response to alkaline stress by selected root canal bacteria.
- 2007
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Ingår i: International endodontic journal. - : Wiley. - 0143-2885 .- 1365-2591. ; 40:5, s. 344-55
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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.
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- Chávez de Paz, Luis, 1974, et al.
(författare)
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Streptococci from root canals in teeth with apical periodontitis receiving endodontic treatment.
- 2005
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Ingår i: Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics. - : Elsevier BV. - 1528-395X .- 1079-2104. ; 100:2, s. 232-41
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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.
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- Lager, Anders, et al.
(författare)
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Acid tolerant streptococci in dentine caries using pH-selective agars
- 2006
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Objectives: To investigate the acid tolerant microflora in dentine caries, with special respect to oral streptococci cultivable on pH-selective agar media, as acid stress might be a major selective force in dentine caries. Methods: Five patients with primary dentine caries lesions (vital teeth, no symptoms) participated in the study. Caries lesions were excavated aseptically under rubber-dam using rose-burs. Dentine sampling was performed using sterile rose-burs at 3 levels: superficially, in the centre and in the cavity floor. Samples were incubated on neutral (blood agar) and pH-selective agars (Todd-Hewitt agar with citrate-phosphate buffer; pH 4.5, 5.0 and 5.5). Numbers of colony-forming units (CFUs) were determined, characterized morphologically, isolated to blood agar and then identified (Gram-reaction, cell- and colony morphology). Each colony type was frozen in skim milk (158 isolates). Isolates described as streptococci were revived, re-incubated (65 isolates) and further characterized by enzymatic- and sugar fermentation tests. Results: The same bacterial counts were recovered from superficial, center and cavity floor, respectively. Each dentine sample exhibited a unique microflora. There was no significant difference in proportions of aciduric microorganisms in different levels in the lesion. Approximately 38% (superficial), 5% (centre) and 38% (cavity floor) of the total cultivable microbiota was able to grow at pH 5.5, a pH value critical for demineralisation of dentine. The acid-tolerant streptococcal isolates included mutans streptococci, S. anginosus, S. constellatus and a group of unidentified streptococci. Lactate consuming taxa were found in one case, but only at pH 5.5. Conclusion: There was no significant difference in numbers of microorganisms on different levels in the lesion. Composition of the dentine caries microflora differs from lesion to lesion. The dentine caries microflora consortia differ from lesion to lesion. A common property of these bacteria was acid tolerance. Approved by the ethical committee Lund University. Funded by Faculty grants.
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- Nylander, Åsa, 1974-, et al.
(författare)
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Structural and functional analysis of the N-terminal domain of the Streptococcus gordonii adhesin Sgo0707
- 2013
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Ingår i: PLOS ONE. - : Public Library Science. - 1932-6203. ; 8:5, s. e63768-
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Tidskriftsartikel (refereegranskat)abstract
- The commensal Streptococcus gordonii expresses numerous surface adhesins with which it interacts with other microorganisms, host cells and salivary proteins to initiate dental plaque formation. However, this Gram-positive bacterium can also spread to non-oral sites such as the heart valves and cause infective endocarditis. One of its surface adhesins, Sgo0707, is a large protein composed of a non-repetitive N-terminal region followed by several C-terminal repeat domains and a cell wall sorting motif. Here we present the crystal structure of the Sgo0707 N-terminal domains, refined to 2.1 Å resolution. The model consists of two domains, N1 and N2. The largest domain, N1, comprises a putative binding cleft with a single cysteine located in its centre and exhibits an unexpected structural similarity to the variable domains of the streptococcal Antigen I/II adhesins. The N2-domain has an IgG-like fold commonly found among Gram-positive surface adhesins. Binding studies performed on S. gordonii wild-type and a Sgo0707 deficient mutant show that the Sgo0707 adhesin is involved in binding to type-1 collagen and to oral keratinocytes.
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