Search

Contains fulltext : 232443.pdf (Publisher’s version ) (Closed access) BACKGROUND: In the Netherlands, access to direct-acting antivirals (DAAs) against hepatitis C virus (HCV) has been unrestricted for chronic infection since 2015. We evaluated whether the nationwide incidence of HCV infections in individuals with HIV has changed since 2015. METHODS: In this retrospective cohort study, data from the ATHENA cohort of people with HIV aged 18 years or older attending any of the 24 HIV treatment centres in the Netherlands between 2000 and 2019 were assessed. We used parametric proportional hazards models with a piecewise exponential survival function to model HCV primary infection and reinfection incidence per 1000 person-years. FINDINGS: Of the 23 590 individuals without previous HCV infection, 1269 cases of HCV primary infection were documented (incidence 5·2 per 1000 person-years [95% CI 5·0-5·5]). The highest incidence was observed in men who have sex with men (MSM; 7·7 per 1000 person-years [7·3-8·2]) and was lower in people who inject drugs (PWID; 1·7 per 1000 person-years [0·7-4·1]) and other key populations (1·0 per 1000 person-years [0·8-1·2]). In MSM, incidence increased in 2007 to 14·3 per 1000 person-years and fluctuated between 8·7 and 13·0 per 1000 person-years from 2008 to 2015. In 2016, incidence declined to 6·1 cases per 1000 person-years and remained steady between 4·1 and 4·9 per 1000 person-years from 2017 to 2019. Of the 1866 individuals with a previous HCV infection, 274 reinfections were documented (incidence 26·9 per 1000 person-years [95% CI 23·9-30·3]). The highest incidence rate was observed in MSM (38·5 per 1000 person-years [33·9-43·7]) and was lower in PWID (10·9 per 1000 person-years [3·5-33·8]) and other key populations (8·9 per 1000 person-years [6·3-12·5]). In MSM, reinfection incidence fluctuated between 38·0 and 88·9 per 1000 person-years from 2006 to 2015, reaching 55·6 per 1000 person-years in 2015. In 2016, reinfection incidence declined to 41·4 per 1000 person-years, followed by further decreases to 24·4 per 1000 person-years in 2017 and 11·4 per 1000 person-years in 2019. INTERPRETATION: The sharp decline in HCV incidence in MSM with HIV shortly after restrictions on DAAs were lifted suggests a treatment-as-prevention effect. HCV incidence was already low in PWID and other groups before unrestricted access. Ongoing HCV transmission is occurring in MSM, as illustrated by a declining but high rate of reinfection, stressing the need for additional preventive measures. FUNDING: Dutch Ministry of Health, Welfare, and Sport.

PURPOSE: To evaluate the 'in vitro' bactericidal effect of the Nd:YAG laser (Genius, MØlsgaard Dental, Copenhagen, Denmark) on six periodontal pathogens.METHODS: Suspensions of six different periodontal pathogens (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Fusobacterium nucleatum and Parvimonas micra) were prepared in small Eppendorff tubes, and exposed to a Nd:YAG laser for five different periods of time. Laser settings used: Power 6 Watt (on a scale of 1-12 W), Frequency 50 Hz, Pulse duration 250 mus. After exposure to the laser, aliquots of the suspensions were spread on blood agar plates for bacterial counting.RESULTS: After 5 s of laser exposure, there was a decrease in total colony forming units for all six selected microorganisms. After 15, 30 and 45 s, no viable bacterial cells could be retrieved.CONCLUSION: In this 'in vitro' model, 15 s of Nd:YAG laser use was found to be effective for total killing of the six tested periodontal pathogens.

Background and aims: Bacteria play an essential role in the pathogenesis of destructive periodontal disease. It has been suggested that not all bacteria associated with periodontitis may be normal inhabitants of a periodontally healthy dentition. In particular, Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans have been isolated infrequently from subjects without periodontitis. The aim of the present study was to compare prevalence and proportions of a number of periodontal bacteria in periodontitis patients and control subjects. Material and methods: In all, 116 consecutive subjects diagnosed with moderate to severe periodontitis (mean age 42.4) and 94 subjects without radiographic evidence of alveolar bone loss (mean age 40.4) were recruited for the study. The gingival condition in the control group varied between gingival health and various degrees of gingivitis. In patients, the deepest pocket in each quadrant was selected for microbiological sampling. In control subjects all mesial and distal sites of all first molars were selected for sampling. All paper points from a patient were pooled and processed for anaerobic cultivation within 6 h after sampling. Clinical variables of sampled sites included bleeding index, probing pocket depth and clinical attachment level. Results: A. actinomycetemcomitans, P. gingivalis, Prevotella intermedia, Bacteroides forsythus, Fusobacterium nucleatum and Peptostreptococcus micros were significantly more often prevalent in patients than in controls. The highest odds ratios were found for P. gingivalis and B. forsythus (12.3 and 10.4 resp.). Other odds ratios varied from 3.1 to 7.7 for A. actinomycetemcomitans and P. micros , respectively. Absolute numbers of target bacteria were all higher in patients, but only the mean percentage of B. forsythus was significantly higher in patients in comparison to controls (P

Background: Periodontal disease in Down's syndrome (DS) is generally characterized by a high degree of bone loss. Bone loss of 5 mm or more is observed in 70% of these subjects. Among DS subjects, considerable differences in disease progression occur. So far, no studies have been conducted in which specific properties of the subgingival microflora have been related to the condition observed. Aims: To investigate (1) the subgingival microflora in DS subjects and other mentally retarded (control) individuals which were matched to the utmost and (2) to investigate the subgingival microflora of a "low-risk" and a "high-risk" group formed in DS subjects. Material and Methods: 17 DS subjects and 17 control subjects were matched with respect to age, plaque level and bleeding on probing. In addition, the DS group was divided in a "low-risk" group (0-2 teeth lost due to periodontal disease n = 6) and a "high-risk" group (6-13 teeth lost due to periodontal disease n = 11). Prevalence and proportions of the putative periodontal pathogens Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Bacteroides forsythus, Peptostreptococcus micros, Fusobacterium nucleation and Campylobacter rectus in the subgingival plaque were determined using anaerobic culture techniques. No differences in the prevalence of distinct suspected periodontopathic bacteria and bacterial subgingival composition between the DS group and the control group could be established. Also no differences in the prevalence of the seven investigated microbial species between the "low-risk" and the "high-risk" group were observed. Conclusions: Because of the lack of differences in microflora between the DS group and the control group, a specific effect of the microbiological composition in the periodontal status of subjects with DS can be excluded in this population. Host factors constitute the more likely explanation of the differences observed in DS.

Background: The etiology of root caries is thought to be identical to coronal caries, though root caries seem to be more complicated because of the higher susceptibility of exposed roots (dentin) by periodontal therapy to demineralization than intact enamel. This implies that mutans streptococci are the most likely pathogens in the development of root caries. Although it is known that both the numbers of mutans streptococci and the frequency of isolation in root caries lesions are negatively correlated with the distance from the gingival margin, the subgingival sulcus has not been considered a possible habitat for mutans streptococci. However, subgingival occurence of mutans streptococci in both untreated and treated periodontal patients has not been documented well in the literature. Objective: To investigate the presence and levels of mutans streptococci in the subgingival plaque of patients (n=154) in different stages of periodontal therapy. The subgingival sulcus may be a possible habitat for mutans streptococci. This localisation of mutans streptococci may be of importance in the development of root caries after periodontal surgery. Materials and methods: In this cross-sectional study, subgingival plaque samples from 154 consecutive adult periodontitis patients were tested for presence and levels of mutans streptococci and putative periodontal pathogens by anaerobic cultures. These patients were divided into 3 groups based on their stage of periodontal treatment: (1) untreated patients; (2) patients after initial periodontal therapy only; (3) patients in the maintenance phase who not underwent periodontal surgery; (4) patients after periodontal surgery. Results: The prevalence of mutans streptococci in the 4 study groups varied from 82% in untreated patients to 94% in maintenance patients. The mean proportion of mutans streptococci was 6.65% in maintenance patients versus 1.86% in untreated patients (p=0.005) and 2.51% in patients after scaling and root planing (p=0.041). Conclusions: The subgingival area is a microbial habitat for mutans streptococci that may be of importance in the development of root caries in periodontitis patients.

Oral candidiasis frequently occurs in individuals with dry mouth syndrome (xerostomia), in immunocompromised patients and in denture wearers. The aim of this study was to develop a formulation which will prolong the retention time of antimicrobial agents at the site of application. The activity against Candida albicans of a synthetic cationic peptide dhvar 1, based on the human fungicidal salivary peptide histatin 5, was tested either in a mixture with the bioadhesive polymer xanthan, or after covalent coupling to this polymer. The presence of xanthan resulted in an increase of the LC50 value of the peptide from 2.6 (S.D.=0.6) to 5.8 (S.D.=4.0). Covalent coupling caused an additional increase of the LC50 value to 18.4 (S. D.=6.7). Coupling caused a reduction of the viscosity and elasticity of the xanthan solution related to the applied concentration of the coupling agent. Incubation of the peptide with clarified human whole saliva resulted in proteolytic degradation of the peptide. In the presence of xanthan the degradation occurred more slowly. It was concluded that xanthan is an appropriate vehicle for antimicrobial peptides in a retention increasing formulation.

Primary Sjogren’s syndrome (SS) is a systemic autoimmune disorder characterised by a chronic, progressive loss of salivary and lacrimal function resulting in symptoms of oral and ocular dryness. The involvement of exocrine glands is the result of a focal, periductal mononuclear cell infiltrate and the subsequent loss of secretory epithelial cells.1 As a consequence, major changes occur in both the salivary flow rate and salivary composition.2-9 In the case of secondary SS a second autoimmune disease is involved, mostly rheumatoid arthritis. The role of saliva in maintaining oral health and even quality of life is obvious in people who are lacking sufficient saliva.10-12 The effects of the reduced salivary flow rate (xerostomia) and changed salivary composition in SS are apparent (table 1): there are problems in eating, speaking, and swallowing12-15 and frequently disturbances in taste perception.16 In addition, reduced clearance of food, changes in microbial ecology and a reduced buffer capacity have their effects on oral health: an increased susceptibility to dental caries and oral infections are important clinical manifestations of the oral component of SS.17 18 When the systemic disease advances, salivary secretion declines further.7 View this table: Table 1 Consequences of xerostomia A reduction of the salivary flow rate below physiological values can be induced by several other causes as well.19 Dry mouth symptoms are known as a side effect of more than 400 drugs.20 21 In most of these cases the level of reduction of the salivary flow is slight and can be compensated for by mechanical or gustatory stimulation. Other common causes of prolonged hyposalivation include other autoimmune disorders such as systemic lupus erythematosus,22 23 uncontrolled diabetes mellitus24 25 and salivary gland injury as a result of radiotherapy in the head and neck region.26 This review describes the current …

In Sjögren's syndrome, salivary glands are affected, resulting in a diminished salivary flow. In the present study, the protein composition, sialic acid content and the amounts of calcium and phosphate of stimulated whole saliva from 43 patients with Sjögren's syndrome, were compared with those of control saliva samples from 17 healthy subjects. The absolute concentrations of albumin, cystatin C, cystatin S, total IgA and total protein, but not amylase, were increased significantly in both primary and secondary Sjögren's syndrome. The output/min of total protein, albumin, amylase, and IgA was, however, decreased in Sjögren patients. These results suggest that the diminished output of salivary defence factors, rather than their absolute concentrations, may be related to the oral health problems seen in Sjögren's syndrome patients.

Rheological properties of unstimulated human whole saliva (CHWS) and human glandular salivas (parotid, submandibular, sublingual, and palatal) of 7 healthy persons were investigated. The viscosity eta' and elasticity eta" of these salivas were measured as a function of oscillating shear rate gamma on an oscillating capillary viscoelasticity analyzer (Vilastic 3). Viscosity eta' and elasticity eta" of total and glandular salivas decreased in the following order: SL > Pal approximately CHWS approximately SM > Par. Rheological behavior of submandibular, palatal and sublingual saliva displayed a comparable pattern, although sublingual saliva showed significantly higher absolute values. The difference in viscoelasticity between submandibular and sublingual saliva was not due to differences in mucin concentration between SM and SL saliva. Flow curves of a range of SL saliva dilutions and flow curves of concentrated SM saliva showed that sublingual saliva was intrinsically more elastic than submandibular saliva.

Parodontitis is een multifactoriele ziekte, dat wil zeggen dat verschillende risico’s zijn vastgesteld voor deze aandoening (Page e.a., 1997). Een risicofactor voor parodontitis wordt gedefinieerd als een factor (kan zowel een omgevings- als gedrags- of biologische factor zijn) die aanwezig is voordat de ziekte zich voordoet en waarvan de relatie tot de ziekte bevestigd is in longitudinale studies. De aanwezigheid van een dergelijke risicofactor verhoogt dus de kans op het ontstaan van de ziekte, terwijl de afwezigheid van de risicofactor de kans juist verkleint (Norderyd, 1998).

De geschiedenis van de orale microbiologie begint bij Antoni van Leeuwenhoek in 1683. Hij beschreef met behulp van een eenvoudige microscoop bacterien in tandplaque. Tevens legde hij het verband tussen het aantal bacterien en geringe mondverzorging.

The introduction of molecular detection of infectious organisms has led to increased numbers of positive findings, as observed for pathogens causing gastroenteritis (GE). However, because little is known about the prevalence of these pathogens in the healthy asymptomatic population, the clinical value of these additional findings is unclear. A case–control study was carried out in a population of patients served by general practitioners in the Netherlands. A total of 2710 fecal samples from case and matched control subjects were subjected to multiplex real-time PCR for the 11 most common bacterial and four protozoal causes of GE. Of 1515 case samples, 818 (54%) were positive for one or more target organisms. A total of 49% of the controls were positive. Higher positivity rates in cases compared to controls were observed for Campylobacter spp., Salmonella spp., Clostridium difficile, enteroinvasive Escherichia coli/Shigella spp., enterotoxigenic E. coli, enteroaggregative E. coli, atypical enteropathogenic E. coli (EPEC), Cryptosporidium parvum/hominis, and Giardia lamblia. However, Dientamoeba fragilis and Shiga-like toxigenic E. coli were detected significantly less frequent in cases than in controls, while no difference in prevalence was found for typical EPEC and enterohemorrhagic E. coli. The association between the presence of microorganisms and GE was the weakest in children aged 0 to 5 years. Higher relative loads in cases further support causality. This was seen for Campylobacter spp., Salmonella spp., enterotoxigenic E. coli, and C. parvum/hominis, and for certain age categories of those infected with C. difficile, enteroaggregative E. coli, and atypical EPEC. For D. fragilis and Shiga-like toxigenic E. coli/enterohemorrhagic E. coli, pathogen loads were lower in cases. Application of molecular diagnostics in GE is rapid, sensitive and specific, but results should be interpreted with care, using clinical and additional background information.

Tobacco smoking has been identified as one major risk factor for destructive periodontal disease. Scaling and root planing have been shown to be less effective in smokers with periodontitis. The aim of the present study was to compare the subgingival microbial flora of treated and untreated smokers and non-smokers.Four independent adult patient groups with periodontitis were included in this investigation: 88 untreated smokers (U-S); 90 untreated non-smokers (U-NS); 119 treated non-smokers (T-NS); and 171 treated smokers (T-S). Clinical variables included cumulative plaque index (CPI), probing depth (PD), clinical attachment level (CAL), cumulative bleeding index (CBI), and cumulative suppuration index (CSI). Paper point samples from the deepest bleeding pocket in each quadrant of the dentition were analyzed for the presence and levels of 6 periodontal bacterial pathogens using anaerobic culture techniques.U-S showed a higher mean cumulative plaque index than U-NS (3.5 versus 2.7). Mean PD and mean CAL were higher in the T-S in comparison to the T-NS group (7.0 versus 6.6 mm and 5.6 versus 4.7 mm, respectively). Microbiological characteristics of U-S were a higher prevalence of Prevotella intermedia/nigrescens and higher mean levels of Peptostreptococcus micros (Pm) and Fusobacterium nucleatum (Fn). T-S patients were characterized by higher prevalence of Bacteroides forsythus (Bf), Pm, and Campylobacter rectus (Cr) and higher mean levels of Pm and Fn. The mean percentage of B. forsythus tended to be higher in the T-S group than in the T-NS group (6.9% versus 5.6%). The relative risk to be infected with Bf, Pm, and Cr was statistically higher in smokers (odds ratios: 1.9, 1.9, and 1.6, respectively). The chance to findor =10% of Bf, Pm, and/or Fn was 3.3 higher in smokers when A. actinomycetemcomitans and P gingivalis were absent. Detection ofor =20% Pm/Fn in treated patients was strongly associated with smoking (odds ratio 13.8, P= 0.002).Smoking is a determining factor for the composition of the subgingival microflora in adult patients with periodontitis and may select for a specific cluster of periodontal pathogens, notably Bf, Pm, Fn, and Cr. On the basis of these observations, smoking, among other criteria, may be one parameter to use in deciding to treat refractory periodontitis in smokers with a systemic antibiotic therapy directed against smoking-associated periodontal bacteria.

A number of polymers which have previously been tested for their applicability as thickening agents in saliva substitutes were studied in vitro for their caries-protective properties. These were: polyacrylic acid, carboxymethylcellulose, xanthan gum, guar gum, hydroxyethylcellulose and porcine gastric mucin. The polymers were tested for their effects on: (1) growth of hydroxyapatite crystals in a supersaturated calcium phosphate solution, (2) dissolution of hydroxyapatite crystals in 50 mM acetic acid, pH 5.2 and (3) demineralization and remineralization of bovine enamel in a pH-cycling model. Growth of hydroxyapatite crystals was strongly inhibited by polyacrylic acid and carboxymethylcellulose at very low concentrations (0.005% w/v). Other polymers displayed lower inhibition of hydroxyapatite crystal growth. Hydroxyapatite dissolution was inhibited by all polymers except by hydroxymethylcellulose and xanthan gum. This occurred both in the presence of the polymers as well as after a 30-min preincubation. In the pH-cycling experiment, bovine enamel specimens with preformed lesions were alternately exposed to a demineralization buffer and a remineralization buffer containing the polymers hydroxyethylcellulose, carboxymethylcellulose, xanthan gum, polyacrylic acid, or porcine gastric mucin. A remineralization buffer containing 1 ppm NaF was used as a positive control. Under the experimental conditions, the control experiment without additives resulted in a net mineral loss (30.6 mumol Ca/cm2 after 14 days of pH cycling). In the presence of 1 ppm NaF, a small mineral gain was observed (8.6 mumol/cm2). All polymers largely inhibited further demineralization (1.2-12.3 mumol/cm2) except polyacrylic acid which, inhibited of its high calcium-binding capacity, caused demineralization, especially in the remineralization buffer (17.1 mumol/cm2). In conclusion, polymers tested in this study, except the polyacrylic acid, reduced the demineralization of enamel in vitro. The precise mechanism of the protective effect is not clear but it is speculated that formation of an absorbed polymer layer on the hydroxyapatite or enamel surface may provide protection against acidic attacks.

The rheological properties of a number of natural and synthetic polysaccharides have been compared with porcine gastric mucin (PGM), a mucin-containing saliva substitute (Saliva Orthana) and with clarified human whole saliva (CHWS). The effects of ionic strength, pH and calcium and fluoride ions on the viscoelastic properties of these polymers have been investigated. Of the polysaccharides tested, xanthan gum and scleroglucan appeared to resemble CHWS most in viscoelastic behavior and may be potential candidates for use in artificial saliva. Both PGM and Saliva Orthana, however, did not show any elastic behavior, whereas a viscosity comparable to human saliva was only observed in highly concentrated solutions. Of the polysaccharides tested, scleroglucan also had mucin-adhesive properties resulting in rheological synergism. This may be the first step in mucoadhesion which may protect underlying oral surfaces in vivo.