Bacterial colonization immediately after installation on oral titanium implants

BACKGROUND: Information on bacterial colonization immediately after dental implant insertion is limited. AIMS: (1) To assess the early colonization on titanium implants immediately after placement and throughout the first 12 post-surgical weeks, (2) to compare the microbiota at interproximal subgingival implant and adjacent tooth sites. MATERIAL AND METHODS: Subgingival plaque samples from implant and neighbouring teeth were studied by checkerboard DNA-DNA hybridization before surgery, 30 min after implant placement, and 1, 2, 4, 8, and 12 weeks after surgery. RESULTS: Comparing bacterial loads at implant sites between 30 min after placement with 1-week data showed that only the levels of Veillonella parvula (P<0.05) differed with higher loads at week 1 post-surgically. Week 12 data demonstrated significantly higher bacterial loads for 15/40 species at tooth sites compared with pre-surgery (P-values varying between 0.05 and 0.01). Between the period immediately after surgery and 12 weeks at implant sites, 29/40 species was more commonly found at 12 weeks. Included among these bacteria at implant sites were Porphyromonas gingivalis (P<0.05), Tannerella forsythia, (P<0.01), and Treponema denticola (P<0.001). Immediately post-surgery 5.9% of implants, and 26.2% of teeth, and at week 12, 15% of implants, and 39.1% of teeth harbored Staphylococcus aureus. Comparing tooth and implant sites, significantly higher bacterial loads were found at tooth sites for 27/40 species after 30 min following implant placement. This difference increased to 35/40 species at 12 weeks post-surgically. CONCLUSIONS: Bacterial colonization occurred within 30 min after implant placement. Early colonization patterns differed between implant and tooth surfaces.

Like will to like: abundances of closely related species can predict susceptibility to intestinal colonization by pathogenic and commensal bacteria

The intestinal ecosystem is formed by a complex, yet highly characteristic microbial community. The parameters defining whether this community permits invasion of a new bacterial species are unclear. In particular, inhibition of enteropathogen infection by the gut microbiota ( = colonization resistance) is poorly understood. To analyze the mechanisms of microbiota-mediated protection from Salmonella enterica induced enterocolitis, we used a mouse infection model and large scale high-throughput pyrosequencing. In contrast to conventional mice (CON), mice with a gut microbiota of low complexity (LCM) were highly susceptible to S. enterica induced colonization and enterocolitis. Colonization resistance was partially restored in LCM-animals by co-housing with conventional mice for 21 days (LCM(con21)). 16S rRNA sequence analysis comparing LCM, LCM(con21) and CON gut microbiota revealed that gut microbiota complexity increased upon conventionalization and correlated with increased resistance to S. enterica infection. Comparative microbiota analysis of mice with varying degrees of colonization resistance allowed us to identify intestinal ecosystem characteristics associated with susceptibility to S. enterica infection. Moreover, this system enabled us to gain further insights into the general principles of gut ecosystem invasion by non-pathogenic, commensal bacteria. Mice harboring high commensal E. coli densities were more susceptible to S. enterica induced gut inflammation. Similarly, mice with high titers of Lactobacilli were more efficiently colonized by a commensal Lactobacillus reuteri(RR) strain after oral inoculation. Upon examination of 16S rRNA sequence data from 9 CON mice we found that closely related phylotypes generally display significantly correlated abundances (co-occurrence), more so than distantly related phylotypes. Thus, in essence, the presence of closely related species can increase the chance of invasion of newly incoming species into the gut ecosystem. We provide evidence that this principle might be of general validity for invasion of bacteria in preformed gut ecosystems. This might be of relevance for human enteropathogen infections as well as therapeutic use of probiotic commensal bacteria.

Microbiological Findings in Subjects With Asymptomatic Oral Lichen Planus: A Cross-Sectional Comparative Study

Background: The bacterial colonization of the oral mucosa was evaluated in patients with asymptomatic oral lichen planus (OLP) and compared to the microbiologic status in mucosally healthy subjects. Methods: Bacteria from patients with clinically and histopathologically diagnosed OLP from the Stomatology Service, Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, were collected with a non-invasive swab system. Samples were taken from OLP lesions on the gingiva and from non-affected sites on the contralateral side of the mouth. The control population did not have OLP and was recruited from the student clinic. All samples were processed with the checkerboard DNA-DNA hybridization method using well-defined bacterial species for the analysis. Results: Significantly higher bacterial counts of Bacteroides ureolyticus (P = 0.001), Dialister species (sp.) (P = 0.006), Staphylococcus haemolyticus (P = 0.007), and Streptococcus agalactiae (P = 0.006) were found in samples taken from OLP lesions compared to sites with no clinical evidence of OLP. Significantly higher bacterial counts were found for Capnocytophaga sputigena, Eikenella corrodens, Lactobacillus crispatus, Mobiluncus curtisii, Neisseria mucosa, Prevotella bivia, Prevotella intermedia, and S. agalactiae at sites with lesions in subjects with OLP compared to sites in control subjects (P <0.001). Conclusions: Microbiologic differences were found between sites with OLP and sites in subjects without a diagnosis of OLP. Specifically, higher counts of staphylococci and S. agalactiae were found in OLP lesions.

One-year bacterial colonization patterns of Staphylococcus aureus and other bacteria at implants and adjacent teeth

AIMS: (i) To assess the pattern of early bacterial colonization on titanium oral implants after installation, at 12 weeks and at 12 months, (ii) to compare the microbiota at submucosal implant sites and adjacent subgingival tooth sites and (iii) to assess whether or not early colonization was predictive of 12-month colonization patterns. MATERIAL AND METHODS: Submucosal/subgingival plaque samples from 17 titanium oral implants and adjacent teeth were analyzed by checkerboard DNA-DNA hybridization 30 min, 12 weeks and 12 months after implant installation. RESULTS: At 12 months, none of the inserted implants had been lost or presented with signs of peri-implantitis. The distribution of sites at implants and teeth with bleeding on probing varied between 2% and 11%. Probing pocket depths < or =3 mm were found at 75% of implant sites. At 12 months, the sum of the bacterial counts of 40 species was statistically significantly higher at tooth compared with implant sites (mean difference: 34.4 x 10(5), 95% confidence interval -0.4 to 69.4, P<0.05). At 12 months, higher individual bacterial counts at tooth sites were found for 7/40 species compared with implant sites. Detection or lack of detection of Staphylococcus aureus at implant sites at 12 weeks resulted in the highest positive (e.g. 80%) and negative (e.g. 90%) predictive values, respectively. Between 12 weeks and 12 months, the prevalence of Tannerella forsythia increased statistically significantly at implant sites (P<0.05). Lack of detection of Porphyromonas gingivalis at 12 weeks yielded a negative predictive value of 93.1% of this microorganism being undetectable at implant sites at 12 months. CONCLUSIONS: Within the limits of this study, the findings showed (i) a few differences in the prevalence of bacterial species between implant and adjacent tooth sites at 12 months and (ii) high positive and negative predictive values for selected bacterial species.

Influence of the menstrual cycle on the oral microbial flora in women: a case-control study including men as control subjects

Changes in the levels of female sex hormones during the menstrual cycle may cause cyclic differences in subgingival bacterial colonization patterns. The purpose of the present study was to test the hypothesis that hormonal changes in the menstrual cycle cause changes in the oral microbiota. METHODS: Bacterial plaque samples were collected in 20 systemically and periodontally healthy women using no hormonal contraceptives (test group) over a period of 6 weeks. Twenty age-matched systemically and periodontally healthy men were assigned to the control group. Samples were processed by checkerboard DNA-DNA hybridization assay, and 74 species were analyzed. RESULTS: No cyclic pattern of bacterial colonization was identified for any of the 74 species studied in women not using hormonal contraceptives. Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) (Y4) was common at the beginning of menstruation (mean: 32%) and increased during the following 2 weeks (36%) in women (P <0.05). No cyclic differences in bacterial presence were found among the men (P values varied between 0.14 and 0.98). Men presented with significantly higher bacterial counts for 40 of 74 species (P <0.001), including Staphylococcus aureus and Pseudomonas aeruginosa but not Porphyromonas gingivalis (P = 0.15) or Tannerella forsythia (previously T. forsythensis) (P = 0.42). CONCLUSIONS: During a menstruation period, cyclic variation in the subgingival microbiota of periodontally healthy women of child-bearing age who were not using oral hormonal contraceptives could not be confirmed. Male control subjects presented with higher levels of many species but also without a cyclic pattern.

Intestinal Microbial Diversity during Early-Life Colonization Shapes Long-Term IgE Levels

Microbial exposure following birth profoundly impacts mammalian immune system development. Microbiota alterations are associated with increased incidence of allergic and autoimmune disorders with elevated serum IgE as a hallmark. The previously reported abnormally high serum IgE levels in germ-free mice suggests that immunoregulatory signals from microbiota are required to control basal IgE levels. We report that germ-free mice and those with low-diversity microbiota develop elevated serum IgE levels in early life. B cells in neonatal germ-free mice undergo isotype switching to IgE at mucosal sites in a CD4 T-cell- and IL-4-dependent manner. A critical level of microbial diversity following birth is required in order to inhibit IgE induction. Elevated IgE levels in germ-free mice lead to increased mast-cell-surface-bound IgE and exaggerated oral-induced systemic anaphylaxis. Thus, appropriate intestinal microbial stimuli during early life are critical for inducing an immunoregulatory network that protects from induction of IgE at mucosal sites.

Internal bacterial colonization of implants: association with peri-implant bone loss

OBJECTIVES The aim of the present longitudinal study was to investigate bacterial colonization of the internal implant cavity and to evaluate a possible association with peri-implant bone loss. METHODS A total of 264 paper point samples were harvested from the intra-implant cavity of 66 implants in 26 patients immediately following implant insertion and after 3, 4, and 12 months. Samples were evaluated for Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Treponema denticola, and Tannerella forsythia as well as total bacterial counts by real-time PCR. Bone loss was evaluated on standardized radiographs up to 25 months after implant insertion. For the statistical analysis of the data, mixed effects models were fitted. RESULTS There was an increase in the frequency of detection as well as in the mean counts of the selected bacteria over time. The evaluation of the target bacteria revealed a significant association of Pr. intermedia at 4 and 12 months with peri-implant bone loss at 25 months (4 months: P = 0.009; 12 months: P = 0.021). CONCLUSIONS The present study could demonstrate a progressive colonization by periodontopathogenic bacteria in the internal cavities of two-piece implants. The results suggest that internal colonization with Pr. intermedia was associated with peri-implant bone loss.