Periodontitis, Dental Procedures, and Young-Onset Cryptogenic Stroke.

Periodontitis is associated with an increased risk of ischemic stroke, and the risk may be particularly high among young people with unexplained stroke etiology. Thus, we investigated in a case-control study whether periodontitis or recent invasive dental treatments are associated with young-onset cryptogenic ischemic stroke (CIS). We enrolled participants from a multicenter case-control SECRETO study including adults aged 18 to 49 y presenting with an imaging-positive first-ever CIS and stroke-free age- and sex-matched controls. Thorough clinical and radiographic oral examination was performed. Furthermore, we measured serum lipopolysaccharide (LPS) and lipotechoic acid (LTA) levels. Multivariate conditional regression models were adjusted for stroke risk factors, regular dentist visits, and patent foramen ovale (PFO) status. We enrolled 146 case-control pairs (median age 41.9 y; 58.2% males). Periodontitis was diagnosed in 27.5% of CIS patients and 20.1% of controls (P < 0.001). In the fully adjusted models, CIS was associated with high periodontal inflammation burden (odds ratio [OR], 95% confidence interval) with an OR of 10.48 (3.18-34.5) and severe periodontitis with an OR of 7.48 (1.24-44.9). Stroke severity increased with the severity of periodontitis, having an OR of 6.43 (1.87-23.0) in stage III to IV, grade C. Invasive dental treatments performed within 3 mo prestroke were associated with CIS, with an OR of 2.54 (1.01-6.39). Association between CIS and invasive dental treatments was especially strong among those with PFO showing an OR of 6.26 (1.72-40.2). LPS/LTA did not differ between CIS patients and controls but displayed an increasing trend with periodontitis severity. Periodontitis and recent invasive dental procedures were associated with CIS after controlling for multiple confounders. However, the role of bacteremia as a mediator of this risk was not confirmed.

Matrix metalloproteinase-7 in periodontitis with type 2 diabetes mellitus.

BACKGROUND AND OBJECTIVE: Elevated levels of matrix metalloproteinase-7 (MMP7) have been observed in serum samples of subjects with type 2 diabetes mellitus (T2DM) and in gingival tissues of subjects with periodontitis. The aim of the present study was to collect in vivo and in silico evidence on the role of MMP7 in the interplay between T2DM and generalized periodontitis (GP). MATERIAL AND METHODS: The extent of MMP7 expression and localization were immunohistochemically analyzed in gingival tissues of patients with GP with T2DM (T2DM/GP, n = 11), systemically healthy patients with GP (n = 7), and systemically and periodontally healthy controls (n = 11). An in silico network model was built to determine the interactions between MMP7 and T2DM pathways. Regulation of neutrophil transmigration by MMP7 was analyzed in a knock-out mice model. RESULTS: In human gingival tissues, the proportion of cells with robust MMP7 expression was elevated in patients with T2DM/GP in comparison to controls (P = .014). According to the in silico analysis, "hydroxyl radical" and "hydrogen peroxide" compounds were among the most central nodes of the network, and were within the shortest paths connecting "glucose" to "MMP7." In MMP7 knock-out mice, an intense accumulation of neutrophils was observed in the gingival epithelium as compared to wild-type mice (P = .0001). CONCLUSION: Elevated MMP7 expression in gingival tissues of patients with T2DM/GP is related to the activation of reactive oxygen species by hyperglycemia. Suppression of MMP7 expression results in impaired neutrophil transmigration in gingiva.

Quorum-sensing molecule dihydroxy-2,3-pentanedione and its analogs as regulators of epithelial integrity.

BACKGROUND AND OBJECTIVE: Quorum-sensing molecules regulate the behavior of bacteria within biofilms and at the same time elicit an immune response in host tissues. Our aim was to investigate the regulatory role of dihydroxy-2,3-pentanedione (DPD), the precursor of universal autoinducer-2 (AI-2), and its analogs (ethyl-DPD, butyl-DPD and isobutyl-DPD) in the integrity of gingival epithelial cells. MATERIAL AND METHODS: Human gingival keratinocytes were incubated with four concentrations (10 µmol L-1 , 1 µmol L-1 , 100 nmol L-1 and 10 nmol L-1 ) of DPD and its analogs for 24 hours. The numbers of viable cells were determined using a proliferation kit, matrix metalloproteinase (MMP)-2 and -9 activities were determined by gelatin zymography, and expression of occludin protein and occludin mRNA were determined by western blotting and RT-qPCR, respectively. RESULTS: Increased cell proliferation was observed in gingival keratinocytes incubated with 100 nmol L-1 of butyl-DPD. MMP-9 activity was elevated in cells incubated with 10 µmol L-1 of ethyl-DPD. On the other hand, MMP-2 activity did not show any significant change when gingival keratinocytes were incubated with or without DPD or analogs. Western blot analyses demonstrated five forms (105, 61, 52.2, 44 and 37 kDa) of occludin. Incubation with 1 µmol L-1 and 100 nmol L-1 of DPD and with 10 nmol L-1 of ethyl-DPD increased dimeric (105 kDa) forms of occludin, while incubation with 100 nmol L-1 of isobutyl-DPD increased monomeric (61 kDa) forms. DPD and ethyl-DPD decreased, and 100 nmol L-1 of isobutyl-DPD and 10 nmol L-1 of butyl-DPD increased, the monomeric (52.2 kDa and 44 kDa) forms of occludin, whereas ethyl-DPD decreased and isobutyl-DPD increased, the low-molecular-weight (37 kDa) forms. According to RT-qPCR analysis, the exposure of gingival keratinocytes to 10 µmol L-1 of isobutyl-DPD up-regulated expression of occludin. CONCLUSION: The results indicate that isobutyl-DPD has the potential to enhance the integrity of the epithelium by stimulating the formation of occluding, without affecting the proliferation or gelatinolytic enzyme activities of the exposed cells. The modulatory effect of an AI-2 analog on the epithelial cell response is shown for the first time.

Mannose-binding lectin gene polymorphism in relation to periodontal infection.

BACKGROUND AND OBJECTIVE: Mannose-binding lectin (MBL) plays an important role in innate immunity. MBL deficiency is usually caused by mutations in exon 1 of the MBL structural gene (MBL2). Our aim was to investigate MBL2 polymorphisms and their relation to salivary levels of periodontal inflammatory/tissue destruction markers and two major periodontitis-associated bacteria. MATERIAL AND METHODS: Salivary samples from 222 subjects were available for genotyping by pyrosequencing. The subjects between 40 and 60 years of age and having a minimum of 20 teeth were divided into three periodontal groups: 80 had generalized periodontitis, 65 had localized periodontitis and 77 were periodontitis-free. A comparison between their MBL2 genotypes and salivary detection rates and levels of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis as well as interleukin -1ß, matrix metalloproteinase -8, and tissue inhibitor of matrix metalloproteinase (TIMP)-1 was performed. RESULTS: The frequencies of the MBL2 wild-type (A/A), heterozygote variants (A/O) and homozygote variants (O/O) were 69.4%, 26.6% and 4%, respectively. In A. actinomycetemcomitans-positive subjects having homozygote or heterozygote MBL2 variants, the salivary concentrations of IL-1ß (p = 0.010) were elevated and those of TIMP-1 (p = 0.001) were decreased. In addition their matrix metalloproteinase -8/TIMP-1 ratio was higher (p < 0.001) and they had more pocket teeth (p = 0.012) than subjects negative for A. actinomycetemcomitans. CONCLUSION: Our findings indicate that the carriage of A. actinomycetemcomitans may facilitate extended periodontal inflammation and destruction in subjects with a variant form of human MBL2.

Alveolar bone loss in relation to toll-like receptor 4 and 9 genotypes and Porphyromonas gingivalis carriage.

Toll-like receptors (TLRs) are highly developed sensors to detect microbe-associated molecular patterns. Functional polymorphisms of the genes TLR4 and TLR9 were found to be associated with alveolar bone loss in a Porphyromonas gingivalis-induced periodontitis model in mice. Our aim was to examine whether such an association can be detected in a group of Finnish adults. Polymorphisms of TLR4 Asp299Gly (rs4986790) and TLR9 rs187084 (1486 T/C) were genotyped by pyrosequencing and PCR from the saliva samples of 223 adults (age range 40-60 years). Alveolar bone loss, measured from panoramic radiographs, were compared between TLR genotype groups according to subjects' salivary carriage of P. gingivalis, measured using a single copy gene-based real-time PCR. The frequencies of TLR4 wild type and heterozygote variants were 87.4 % and 12.6 %, respectively, while those of TLR9 wild type, heterozygote, and homozygote variants were 25.6 %, 39.1 %, and 35.3 %, respectively. In the TLR4 heterozygote group, P. gingivalis-positive subjects had more alveolar bone loss than P. gingivalis-negative subjects (p = 0.027), while no difference was observed in the wild type group. P. gingivalis-negative individuals with TLR9 heterozygotes exhibited significantly less alveolar bone loss compared to those with TLR9 wild type (p = 0.007). Polymorphisms of TLR4 in P. gingivalis carriers seem to expose to alveolar bone loss. Polymorphisms of TLR9 can be protective against alveolar bone loss in the absence of P. gingivalis.

Longitudinal study of salivary proteinases during pregnancy and postpartum.

BACKGROUND AND OBJECTIVE: Matrix metalloproteinases (MMPs) and their regulators are connected to periodontal inflammation and destruction. However, the presence and role of the salivary MMPs in pregnancy-related gingivitis are not well known. Our longitudinal study aimed to monitor salivary proteinase levels and possible changes, and relate them to periodontal status during pregnancy and postpartum. MATERIAL AND METHODS: Salivary samples were collected from 30 periodontally healthy pregnant women five times (once during each trimester, 4-6 wk after delivery and after lactation) and, as their controls, from 24 non-pregnant women three times (during successive months). Periodontal examination included visible plaque index, bleeding on probing, probing pocket depth and clinical attachment level measurements. Matrix metalloproteinase-8 levels were measured by immunofluorometric assay, and MMP-2 and MMP-9 levels and molecular forms by gelatin zymography. Salivary elastase, myeloperoxidase and tissue inhibitor of matrix metalloproteinase-1 levels were measured by ELISA. RESULTS: Elastase concentrations maintained stable during the follow-up, while myeloperoxidase concentrations increased significantly after delivery. During pregnancy, MMP-8 concentrations were significantly lower than postpartum concentrations, being lowest during the second trimester and highest after delivery, and varying inversely to pregnancy gingivitis, observed as elevated percentages of bleeding on probing and probing pocket depth during the second and third trimester. In pregnant women, the highest MMP-2 and MMP-9 levels were found in saliva after lactation. In the control group, both clinical and enzymological findings remained stable during the follow-up period. CONCLUSION: Our results suggest that hormonal changes during pregnancy induce or enhance susceptibility to gingivitis, while salivary proteinase and myeloperoxidase levels are reduced.

Does the frequency of Prevotella intermedia increase during pregnancy?

INTRODUCTION: The former Bacteroides intermedius, currently including Prevotella intermedia and Prevotella nigrescens, has been associated with hormone-induced pregnancy gingivitis. The aim of the present longitudinal study was to determine whether only P. intermedia or P. nigrescens, or both species, are involved in the demonstrated microbial shift during pregnancy. METHODS: Subgingival plaque and saliva samples, collected from 30 healthy pregnant women and 24 healthy non-pregnant women as their controls, were examined for the presence of pigmented gram-negative anaerobes. Altogether 2628 isolates were preliminarily identified as P. intermedia sensu lato, based on phenotypic testing. Their further identification was performed by using a 16S ribosomal DNA-based polymerase chain reaction (PCR). RESULTS: A mean of 8.3 P. intermedia sensu lato isolates from each subject/sampling was examined. During the second trimester, the mean number of P. intermedia sensu lato in plaque increased along with increasing signs of pregnancy gingivitis, and then both decreased. After delivery, gingival inflammation still decreased while the number of P. intermedia sensu lato transiently increased both in plaque and saliva. In the present study, the vast majority of isolates (95.3%) proved to be P. nigrescens and 2.5% were P. intermedia. The remaining 2.2% of the isolates could not be identified with PCR as P. intermedia or P. nigrescens. The corresponding percentages in the control population were 94.2%, 5.5%, and 0.3%. CONCLUSION: In the oral cavity of relatively young women without periodontitis, P. nigrescens, unlike P. intermedia, is a frequent finding. Conceivably, pregnant women harbor increasing numbers of P. nigrescens associated with pregnancy gingivitis.

Prevotella intermedia ATCC 25611 targets host cell lamellipodia in epithelial cell adhesion and invasion.

INTRODUCTION: The Prevotella intermedia group bacteria, namely P. intermedia, Prevotella nigrescens, and Prevotella pallens, are phylogenetically closely related and potentially connected with oral and gastrointestinal tract disease pathogenesis. The aim of the present study was to examine whether these species differ in their capabilities of adhesion to and invasion of epithelial cells. METHODS: Adhesion and invasion were assayed by standard antibiotic/culture assays and fluorescent microscopy techniques. The effect of Prevotella strains on epithelial cell viability was measured using a commercial cell proliferation assay. RESULTS: The strains P. intermedia ATCC 25611 and P. nigrescens ATCC 33263 adhered to epithelial cells, the adhesion numbers of P. intermedia being twice as high as those of P. nigrescens. These strains invaded epithelial cells but invasion was weak. The adhesion of P. intermedia was specifically targeted to epithelial cell lamellipodia. The number of adhered P. intermedia cells increased or decreased when the formation of lamellipodia was stimulated or inhibited, respectively. None of the tested strains showed toxic effects on epithelial cells; a clinical P. intermedia strain even increased the number of viable cells by about 20%. CONCLUSION: The results suggest that among the P. intermedia group bacteria, P. intermedia and P. nigrescens type strains can adhere to and invade epithelial cells, the capability of P. intermedia ATCC 25611(T) being highest in this context. This strain proved to have a special affinity in binding to epithelial cell lamellipodia.

Stimulation of epithelial cell matrix metalloproteinase (MMP-2, -9, -13) and interleukin-8 secretion by fusobacteria.

BACKGROUND/AIMS: Bacterial pathogens involved in periodontal diseases exert their destructive effects primarily by stimulating the host cells to increase their secretion of proinflammatory cytokines and matrix metalloproteinases (MMPs). This study aimed to determine the epithelial cell matrix metalloproteinase and interleukin-8 (IL-8) secretion upon exposure to fusobacteria. METHODS: Eight different oral and non-oral Fusobacterium strains were incubated with HaCaT epithelial cells. Gelatin zymography and Western blot analysis were performed to detect collagenase 3 (MMP-13), gelatinase A (MMP-2), gelatinase B (MMP-9), and IL-8 secretion by epithelial cells. RESULTS: All Fusobacterium strains, especially Fusobacterium necrophorum ATCC 25286, Fusobacterium nucleatum ATCC 25586, and Fusobacterium varium ATCC 51644, increased MMP-9 and MMP-13 secretion. Fusobacterium simiae ATCC 33568, and to a lesser extent F. nucleatum and F. necrophorum, increased epithelial MMP-2 secretion. F. nucleatum and F. necrophorum also increased IL-8 secretion. F. varium ATCC 27725, a strain that only weakly stimulated MMP production, strongly increased the IL-8 production, suggesting that their expression is differently regulated. CONCLUSION: We conclude that the pathogenic potential of fusobacteria may partly result from their ability to stimulate secretion of MMP-9, MMP-13, and IL-8 from epithelial cells.

European surveillance study on antimicrobial susceptibility of Gram-positive anaerobic cocci.

Gram-positive anaerobic cocci (GPAC) are a heterogeneous group of microorganisms frequently isolated from local and systemic infections. In this study, the antimicrobial susceptibilities of clinical strains isolated in 10 European countries were investigated. After identification of 299 GPAC to species level, the minimum inhibitory concentrations of penicillin, imipenem, clindamycin, metronidazole, vancomycin and linezolid were determined by the agar dilution method according to the Clinical and Laboratory Standards Institute. The majority of isolates were identified as Finegoldia magna and Parvimonas micra (formerly Peptostreptococcus micros), isolated from skin and soft tissue infections. All isolates were susceptible to imipenem, metronidazole, vancomycin and linezolid. Twenty-one isolates (7%) were resistant to penicillin (n=13) and/or to clindamycin (n=12). Four isolates were resistant to both agents. The majority of resistant isolates were identified as F. magna and originated from blood, abscesses and soft tissue infections.

Effect of triclosan/copolymer-containing toothpaste on the association between plaque and gingival bleeding: a randomized controlled clinical trial.

AIM: To study longitudinal associations between plaque and gingival bleeding and multilevel variance/covariance structures after introducing triclosan-containing toothpaste. MATERIAL AND METHODS: A 10-week, randomized, two-arm, double-masked, controlled clinical trial was conducted in 34 healthy, non-smoking females with plaque-induced gingivitis. Clinical periodontal examinations were repeated every other week. At week 4, test toothpaste containing 0.24% sodium monofluorophosphate, 0.3% triclosan, and 2% polyvinyl-methyl ether maleic acid; or control toothpaste containing 0.76% sodium monofluorophosphate and 0.1% sodium fluoride, were randomly distributed. RESULTS: Multivariate multilevel models indicated that, after introducing experimental toothpastes, subject random error was reduced from 0.6 to below 0.2. The odds ratio (OR) of bleeding on probing (BOP) was about 30% less in the test than in the control group (p<0.01). At the end of the experiment, ORs for BOP and plaque index scores 1-3 (reference 0) were 2.1-2.4 in the control group, but 1.1-1.9 in the test group (p<0.05). No effects on plaque levels and calculus were observed. CONCLUSIONS: Multivariate multilevel modelling allows the study of fixed and random effects of experimental toothpastes on gingival inflammation in small sample. Triclosan appears to attenuate the causal association between supragingival plaque and gingival bleeding in gingivitis.

Clostridium clostridioforme: a mixture of three clinically important species.

Clostridium clostridioforme shows much variability in phenotypic and antimicrobial susceptibility tests, suggesting it may be more than a single species even though all strains share unique morphology. This study was designed to determine if there are multiple species and, if so, to demonstrate the differences that exist between them. A total of 107 strains of C. clostridioforme were investigated by sequencing of the 16S rRNA gene, phenotypic studies, and antimicrobial susceptibility testing. In addition, clinical data from patients whose infections yielded an organism identified as C. clostridioforme was reviewed. Data from the above studies revealed three principal species in what has been called C. clostridioforme: Clostridium bolteae, C. clostridioforme, and Clostridium hathewayi. Each species may be distinguished by certain phenotypic tests. All three species were involved in infections, including bacteremia. C. clostridioforme appears to be associated with more serious or invasive human infections than the other two species in the group. Resistance to penicillin G is common and is due to beta-lactamase production. Resistance to clindamycin and moxifloxacin is also seen. The three species differ in terms of virulence and antimicrobial resistance. "C. clostridioforme" actually represents three distinct species that are different in terms of 16S rRNA sequences, phenotypic characteristics, and antimicrobial susceptibility. It is important for microbiology laboratories to distinguish between these species and for clinicians to be aware of the differences between them.

Variance components of gingival thickness.

OBJECTIVES: Distinct periodontal phenotypes have been identified by cluster analysis, which is an explorative method with very low external validity. The aim of the present study was to investigate variance components of facial gingival thickness in young adults with mild gingivitis. MATERIAL AND METHODS: Thirty-three non-smoking females, 18-23 years of age, with mild or moderate plaque-induced gingivitis participated. Gingival thickness was measured at every tooth present by use of ultrasound technology to the next 0.1 mm with a lowest measurement of 0.5 mm. Periodontal probing depth and clinical attachment level were measured with a pressure-controlled probe. Gingival bleeding index was assessed after probing on a 0-2 scale, where 1 was slight, and 2 was profuse bleeding on probing. The Silness-Loe plaque index was recorded. Multilevel variance components and random intercept models were built. RESULTS: A 2-level (subject, tooth) variance component model of gingival thickness without any explanatory variable revealed an intercept (mean) of 0.93 +/- 0.02 mm. Subject variation of gingival thickness amounted to 4.2% of the total variance. Addition of tooth- and subject-related covariates to the model revealed, after adjusting for tooth type, an association with periodontal probing depth (estimated coefficient 0.067 +/- 0.025), and considerable association with average bleeding index (-0.395 +/- 0.149) and plaque index (0.125 +/- 0.048). Variation at the tooth level was drastically reduced; subject variation amounted to 5.2%. CONCLUSION: Gingival thickness is mainly associated with tooth-related variables. Bleeding tendency is higher if gingiva is thin. Subject variability related to periodontal phenotype may add to the total variance, however, to a very low extent.

Impact of antimicrobial exposure and beta-lactamase-producing bacteria on salivary beta-lactamase activity in infancy.

Beta-lactamase production by oral bacteria is common in infancy and is associated with use of antimicrobial agents in infants. The present longitudinal study aimed to examine the frequency of salivary beta-lactamase activity (SbetaA), to compare SbetaA with the presence of beta-lactamase-producing (beta+) aerobic and anaerobic species in saliva, and to estimate the impact of antimicrobial exposure on the emergence of SbetaA in healthy infants during their first year of life. At 6 months, SbetaA was detected in 46% infants; 89% SbetaA-positive infants and 55% SbetaA-negative infants harboured beta+ species at this time (OR 7.08; CI 1.31-38.34). At 12 months, SbetaA was detected in 54% infants. Exposure to antimicrobials during the first year of life increased the risk (OR 2.60; CI 0.72-9.36) of having SbetaA.

Clonal persistence of oral Fusobacterium nucleatum in infancy.

Once established, early-colonizing bacterial species tend to persist in the mouth. To obtain detailed information on the population dynamics of early-colonizing oral anaerobes, we examined the clonal diversity and persistence of clones among oral Fusobacterium nucleatum populations during the first 2 yrs of life. Consecutive salivary samples from 12 infants, collected at 2, 6, 12, 18, and 24 mos of age, yielded a total of 546 F. nucleatum isolates for clonal typing with arbitrarily primed PCR (AP-PCR). Up to 7 AP-PCR types were simultaneously detected in each sample. In 11 out of the 12 infants examined, AP-PCR types persisted for up to 1 yr. Strain turnover rate was high during the first year of life, but then the occurrence of persistent clones increased. This study indicates a wide genetic diversity within the species and provides evidence for the increasing persistence of F. nucleatum clones in the oral cavity with age.

Age-related frequency of penicillin resistance of oral Veillonella.

Veillonella spp. are early colonizing inhabitants in the mouth. As part of studies on penicillin resistance among oral indigenous anaerobic microbiota in childhood, the aim of the present longitudinal study was to examine the emergence of resistant strains in Veillonella populations. Altogether 305 Veillonella isolates from saliva of 49 healthy infants followed from 2 to 24 months of age were examined for their in vitro susceptibility to penicillin G and, further, 20 penicillin-resistant isolates representing 5 MIC categories to ampicillin, amoxicillin, amoxicillin/clavulanate, cefoxitin, and beta-lactamase production. In infants positive for oral Veillonella, the recovery rate of penicillin-resistant (MIC >/=2 microg/ml) strains increased with age up to 68%, however, most infants simultaneously harbored penicillin-susceptible strains. During the follow-up, the MIC(50) increased from 0.5 microg/ml to 2 microg/ml. In addition to penicillin G, 8/20 strains also showed reduced susceptibility to ampicillin and/or amoxicillin but none produced beta-lactamase. Our study suggests other mechanisms than enzymatic degradation of beta-lactam ring for resistance of oral Veillonella to penicillin.

Establishment of streptococci in the upper respiratory tract: longitudinal changes in the mouth and nasopharynx up to 2 years of age.

As part of a series of longitudinal studies on the development of the indigenous microflora of the upper respiratory tract, the establishment of streptococci in the oral cavity and nasopharynx and IgA1 protease production by the early streptococcal flora was examined in 50 healthy Caucasian infants at the ages of 2, 6, 12, 18 and 24 months. In the oral cavity, streptococci were found in all infants on every sampling occasion, Streptococcus mitis biovar 1 being the main finding in each age group. S. salivarius and S. mitis biovar 2 reached their highest prevalence during the first year of life, whereas the prevalence of S. oralis and S. sanguis showed no significant increase before 12 months of age. Salivary streptococci mainly consisted of the above-mentioned species during the follow-up period. In contrast to the oral cavity, no stable colonisation pattern was observed for viridans streptococci in the nasopharynx. S. mitis biovar 1 and S. pneumoniae, a traditional respiratory pathogen, were the principal streptococcal species among nasopharyngeal isolates. IgA1 protease production by early streptococci was common in infancy. Among the oral streptococcal microflora, S. mitis biovar 1 (especially during the first year of life) and S. oralis and S. sanguis constituted the main species responsible for this enzyme activity. In the nasopharynx, IgA1 protease was produced by S. mitis biovar 1, S. oralis and S. pneumoniae. In conclusion, streptococcal colonisation differs in these two close habitats in the upper respiratory tract.

Phenotypic identification of Actinomyces and related species isolated from human sources.

Recent advancements in chemotaxonomic and molecular biology-based identification methods have clarified the taxonomy of the genus Actinomyces and have led to the recognition of several new Actinomyces and related species. Actinomyces-like gram-positive rods have increasingly been isolated from various clinical specimens. Thus, an easily accessible scheme for reliable differentiation at the species level is needed in clinical and oral microbiology laboratories, where bacterial identification is mainly based on conventional biochemical methods. In the present study we designed a two-step protocol that consists of a flowchart that describes rapid, cost-efficient tests for preliminary identification of Actinomyces and closely related species and an updated more comprehensive scheme that also uses fermentation reactions for accurate differentiation of Actinomyces and closely related species.

Development of oral bacterial flora in young children.

The intimate relationship with bacteria is a fundamental factor in the health status of an individual. After birth infants are exposed to continuous person-to-person and environmental contacts with microbes, and the development of the indigenous microflora begins on the surfaces of the human body. In a developing ecosystem microbial colonization may easily occur because of the still inadequate host response. Adhesion is the initial event in the colonization of bacteria. In the mouth, only mucosal surfaces are available during the first months of life. After teeth emerge, the number of attachment sites and potential niches increases significantly. Bacteria adhere not only to oral surfaces but also to each other, forming multigeneric communities where specific partner relationships influence their composition and stability. Viridans streptococci and a strictly anaerobic species, Fusobacterium nucleatum, are of interest in this context. The oral colonization pattern differs between individuals already in infancy; variable bacterial load in saliva of attendants and other close contacts and the frequency of this bacterial exposure may partly account for individual differences. In addition, the exposure of an infant to antibiotics affects the quality of colonizing bacteria. This article presents an overview of the age-related acquisition of oral bacteria and the role of the indigenous oral microflora in health and disease.