| 1. |
- Basic, Amina, et al.
(author)
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Estimation of bacterial hydrogen sulfide production in vitro.
- 2015
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In: Journal of oral microbiology. - : Informa UK Limited. - 2000-2297. ; 7
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Journal article (peer-reviewed)abstract
- Oral bacterial hydrogen sulfide (H2S) production was estimated comparing two different colorimetric methods in microtiter plate format. High H2S production was seen for Fusobacterium spp., Treponema denticola, and Prevotella tannerae, associated with periodontal disease. The production differed between the methods indicating that H2S production may follow different pathways.
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| 2. |
- Basic, Amina, et al.
(author)
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Hydrogen sulfide production from subgingival plaque samples.
- 2015
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In: Anaerobe. - : Elsevier BV. - 1095-8274 .- 1075-9964. ; 35:Part A, s. 21-27
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Journal article (peer-reviewed)abstract
- Periodontitis is a polymicrobial anaerobe infection. Little is known about the dysbiotic microbiota and the role of bacterial metabolites in the disease process. It is suggested that the production of certain waste products in the proteolytic metabolism may work as markers for disease severity. Hydrogen sulfide (H2S) is a gas produced by degradation of proteins in the subgingival pocket. It is highly toxic and believed to have pro-inflammatory properties. We aimed to study H2S production from subgingival plaque samples in relation to disease severity in subjects with natural development of the disease, using a colorimetric method based on bismuth precipitation. In remote areas of northern Thailand, adults with poor oral hygiene habits and a natural development of periodontal disease were examined for their oral health status. H2S production was measured with the bismuth method and subgingival plaque samples were analyzed for the presence of 20 bacterial species with the checkerboard DNA-DNA hybridization technique. In total, 43 subjects were examined (age 40-60 years, mean PI 95±6.6%). Fifty-six percent had moderate periodontal breakdown (CAL>3<7mm) and 35% had severe periodontal breakdown (CAL>7mm) on at least one site. Parvimonas micra, Filifactor alocis, Porphyromonas endodontalis and Fusobacterium nucleatum were frequently detected. H2S production could not be correlated to periodontal disease severity (PPD or CAL at sampled sites) or to a specific bacterial composition. Site 21 had statistically lower production of H2S (p=0.02) compared to 16 and 46. Betel nut chewers had statistically significant lower H2S production (p=0.01) than non-chewers. Rapid detection and estimation of subgingival H2S production capacity was easily and reliably tested by the colorimetric bismuth sulfide precipitation method. H2S may be a valuable clinical marker for degradation of proteins in the subgingival pocket.
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| 3. |
- Blomqvist, Susanne, 1953, et al.
(author)
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Phenotype, genotype, and antibiotic susceptibility of Swedish and Thai oral isolates of Staphylococcus aureus
- 2015
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In: Journal of Oral Microbiology. - : Informa UK Limited. - 2000-2297. ; 7:1, s. 1-7
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Journal article (peer-reviewed)abstract
- Objective: The present study investigated phenotypes, virulence genotypes, and antibiotic susceptibility of oral Staphylococcus aureus strains in order to get more information on whether oral infections with this bacterium are associated with certain subtypes or related to an over-growth of the S. aureus variants normally found in the oral cavity of healthy carriers. Materials and methods: A total number of 157 S. aureus strains were investigated. Sixty-two strains were isolated from Swedish adults with oral infections, 25 strains were from saliva of healthy Swedish dental students, and 45 strains were from tongue scrapings of HIV-positive subjects in Thailand, and 25 Thai strains from non-HIV controls. The isolates were tested for coagulase, nitrate, arginine, and hemolysin, and for the presence of the virulence genes: hlg, clfA, can, sdrC, sdrD, sdrE, map/eap (adhesins) and sea, seb, sec, tst, eta, etb, pvl (toxins). MIC90 and MIC50 were determined by E-test against penicillin V, oxacillin, amoxicillin, clindamycin, vancomycin, fusidic acid, and cefoxitin. Results: While the hemolytic phenotype was significantly (p<0.001) more common among the Thai strains compared to Swedish strains, the virulence genes were found in a similar frequency in the S. aureus strains isolated from all four subject groups. The Panton-Valentine leukocidin (PVL) genotype was found in 73-100% of the strains. More than 10% of the strains from Swedish oral infections and from Thai HIVpositives showed low antibiotic susceptibility, most commonly for clindamycin. Only three methicillinresistant S. aureus (MRSA) strains were identified, two from oral infections and one from a Thai HIV patient. Conclusions: S. aureus is occasionally occurring in the oral cavity in both health and disease in Sweden and Thailand. It is therefore most likely that S. aureus in opportunistic oral infections originate from the oral microbiota. S. aureus should be considered in case of oral infections and complaints and the antibiotic susceptibility (including MRSA) should regularly be checked. The frequent presence of S. aureus, although in low numbers among students and staff, emphasizes the importance of standard infection control precautions and of using diagnostic test in the dental clinic. © 2015 Susanne Blomqvist et al.
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| 4. |
- Boustedt, Katarina, et al.
(author)
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Salivary microflora and mode of delivery: a prospective case control study.
- 2015
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In: BMC oral health. - : Springer Science and Business Media LLC. - 1472-6831. ; 15:1
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Journal article (peer-reviewed)abstract
- Previous cross-sectional studies have suggested that the mode of delivery can influence the composition of oral microflora. The aim of this prospective study was to compare the salivary colonization in vaginally delivered children with children delivered by Caesarian section (C-section) during their first 6months of life.
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| 5. |
- Charalampakis, Georgios, et al.
(author)
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Effect of cleansing of biofilm formed on titanium discs.
- 2015
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In: Clinical oral implants research. - : Wiley. - 1600-0501 .- 0905-7161. ; 26:8, s. 931-936
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Journal article (peer-reviewed)abstract
- To study the combined effect of mechanical and chemical cleansing on a 4-day biofilm grown intra-orally on titanium discs with different surface characteristics.
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| 6. |
- Dahlén, Gunnar, 1944, et al.
(author)
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Methodological issues in the quantification of subgingival microorganisms using the checkerboard technique.
- 2015
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In: Journal of microbiological methods. - : Elsevier BV. - 1872-8359 .- 0167-7012. ; 110, s. 68-77
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Journal article (peer-reviewed)abstract
- The reproducibility and reliability of quantitative microbiological assessments using the DNA-DNA hybridization "checkerboard method" (CKB) were assessed. The data originated from 180 chronic periodontitis patients, who were enrolled in a clinical trial and sampled at baseline, and 3 and 12m post-therapy. The samples were divided into two portions allowing evaluation of reproducibility. In total, 531 samples were analyzed in a first run, using standard bacterial preparations of cells and 513 samples were accessible for analysis in the second, using standards based on purified DNA from the species. The microbial probe panel consisted of periodontitis marker bacteria as well as non-oral microorganisms. Three different ways of quantifying and presenting data; the visual scoring method, VSM, the standard curve method, SCM, and the percent method, PM, were compared. The second set of analyses based on the use of standard preparations of pure DNA was shown to be more consistent than the first set using standards based on cells, while the effect of storage time per se up to 2.5y seemed to be marginal. The best reproducibility was found for Tannerella forsythia, irrespective of quantification technique (Spearman's rho=0.587, Pearson's r≥0.540). The percent method (PM) based on percent of High Standard (10(6) cells) was more reliable than SCM based on a linear calibration of the High Standard and a Low Standard (10(5) cells). It was concluded that the reproducibility of the CBK method varied between different bacteria. High quality and pure specific DNA whole genomic probes and standards may have a stronger impact on the precision of the data than storage time and conditions.
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| 7. |
- Kistler, J. O., et al.
(author)
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The oral microbiome in human immunodeficiency virus (HIV)-positive individuals
- 2015
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In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 64:Part: 9, s. 1094-1101
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Journal article (peer-reviewed)abstract
- Human immunodeficiency virus (HIV) infection is associated with a range of oral conditions, and increased numbers of disease-associated microbial species have previously been found in HIV-positive subjects. The aim of this study was to use next-generation sequencing to compare the composition of the oral microbiome in HIV-positive and -negative individuals. Plaque and saliva were collected from 37 HIV-positive individuals and 37 HIV-negative individuals, and their bacterial composition determined by pyrosequencing of partial 16S rRNA genes. A total of 855 222 sequences were analysed. The number of species-level operational taxonomic units (OTUs) detected was significantly lower in the saliva of HIV-positive individuals (mean=303.3) than in that of HIV-negative individuals (mean=365.5) (P<0.0003). Principal coordinates analysis (PCoA) based on community membership (Jaccard index) and structure (Yue and Clayton measure of dissimilarity) showed significant separation of plaque and saliva samples [analysis of molecular variance (AMOVA), P<0.001]. PCoA plots did not show any clear separation based on HIV status. However, AMOVA indicated that there was a significant difference in the community membership of saliva between HIV-positive and -negative groups (P=0.001). Linear discriminant analysis effect size revealed an OTU identified as Haemophilus parainfluenzae to be significantly associated with HIV-positive individuals, whilst Streptococcus mitis/HOT473 was most significantly associated with HIV-negative individuals. In conclusion, this study has confirmed that the microbial composition of saliva and plaque is different. The oral microbiomes of HIV-positive and -negative individuals were found to be similar overall, although there were minor but significant differences in the composition of the salivary microbiota of the two groups.
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| 8. |
- Pahumunto, N., et al.
(author)
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Aggregatibacter actinomycetemcomitans serotypes and DGGE subtypes in Thai adults with chronic periodontitis
- 2015
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In: Archives of Oral Biology. - : Elsevier BV. - 0003-9969 .- 1879-1506. ; 60:12, s. 1789-1796
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Journal article (peer-reviewed)abstract
- © 2015 Elsevier Ltd. All rights reserved. Objective To investigate the distribution of Aggregatibacter actinomycetemcomitans serotypes and DGGE subtypes among isolates from Thai chronic periodontitis patients. Design Forty-four adult Thai periodontitis patients were assessed by a full mouth recording for CAL, PPD, and BOP. Seventy-nine strains of A. actinomycetemcomitans were isolated from deep pockets on selective TSBV agar and 17 strains were isolated from shallow pockets. The strains were serotyped using PCR and subtyped using DGGE. Results The prevalence of A. actinomycetemcomitans was 84.1%. Non-serotypeable A. actinomycetemcomitans strains occurred equally frequent as serotypeable (54.5%); serotype a 18.2%, serotype c 15.9%, serotype e 9.1%, and serotype f 11.4%. Serotype b and d were not detected. A JP2 like strain but serotyped as c was isolated from two patients, and another two strains showed an 886 bp insertion on the ltx promoter of their A. actinomycetemcomitans isolates. DGGE typing disclosed 16 different subtypes among the non-serotypeable strains. Two of them (NS1 and NS2) were more common (12.7 and 10.1%) among the strains than the other 14 subtypes (<5.1%). Most patients showed only one subtype (32.4%) but 29.7% had 2 and 3 different subtypes while 8.1% revealed 4 subtypes in one and the same deep pocket. Conclusion This study showed a greater subtype diversity of A. actinomycetemcomitans predominated by non-serotypeable strains than previously reported in an adult Thai population. It was also revealed for the first time that isolates with a 530 bp deletion or 886 bp insertion of the ltx promoter were serotyped as serotype c.
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| 9. |
- Pahumunto, Nuntiya, et al.
(author)
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Virulence of Aggregatibacter actinomycetemcomitans serotypes and DGGE subtypes isolated from chronic adult periodontitis in Thailand.
- 2015
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In: Anaerobe. - : Elsevier BV. - 1095-8274 .- 1075-9964. ; 36, s. 60-4
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Journal article (peer-reviewed)abstract
- A high proportion of non-serotypeable isolates of Aggregatibacter actinomycetemcomitans among Thai periodontitis cases has been previously reported. The aim of this study was to investigate the expression of leukotoxin and toxicity, cytolethal distending toxin (Cdts), and internalization and the killing effect on fibroblasts by A.actinomycetemcomitans subtypes from Thai chronic periodontitis cases. A total of 96 A.actinomycetemcomitans strains from 37 periodontitis cases, previously serotyped with PCR and subtyped with DGGE, were examined for the presence of the ltx gene and cdt genes (cdtBC), and tested for leukotoxin expression, leukotoxicity, internalization, and apoptosis of fibroblast cells. The ltx gene was present in all isolates, while 84.4% showed the cdtBC gene. Two strains with a JP2-like ltx gene with a deletion of 530bp in the promoter region, serotyped as c, showed virulence of similar magnitude to the JP2 strain. Furthermore, a higher virulence was found in the two non-serotypeable DGGE subtypes, NS1 and NS2, compared with the serotypeable strains (serotype a-f, serotype b and d were absent). Generally, the virulence of strains obtained from deep periodontal pockets was higher than those isolated from shallow non-bleeding pockets. A.actinomycetemcomitans subtypes isolated from adult Thais with chronic periodontitis showed a highly variable virulence, leukotoxin expression, leukotoxicity, internalization and apoptosis of fibroblast, and are regulated both genetically and environmentally.
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| 10. |
- Piwat, S, et al.
(author)
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Site-specific dental plaque pH in 13-year-old Thai schoolchildren.
- 2015
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In: Clinical oral investigations. - : Springer Science and Business Media LLC. - 1436-3771 .- 1432-6981. ; 19:9, s. 2179-2186
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Journal article (peer-reviewed)abstract
- The aim of this paper was to study pH conditions between dental sites, taking account the presence of caries, calculus, and microbial composition and alkali production.
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