Oral microbiota of adolescents with dental caries: A systematic review

OBJECTIVE

This systematic review summarizes the current knowledge on the association between the oral microbiota and dental caries in adolescents.

DESIGN

An electronic search was carried out across five databases. Studies were included if they conducted research on generally healthy adolescents, applied molecular-based microbiological analyses and assessed caries status. Data extraction was performed by two reviewers and the Newcastle-Ottawa Scale was applied for quality assessment.

RESULTS

In total, 3935 records were reviewed which resulted in a selection of 20 cross-sectional studies (published 2005-2022) with a sample size ranging from 11 to 614 participants including adolescents between 11 and 19 years. The studies analyzed saliva, dental biofilm or tongue swabs with Checkerboard DNA-DNA hybridization, (q)PCR or Next-Generation Sequencing methods. Prevotella denticola, Scardoviae Wiggsiae, Streptococcus sobrinus and Streptococcus mutans were the most frequently reported species presenting higher abundance in adolescents with caries. The majority of the studies reported that the microbial diversity was similar between participants with and without dental caries.

CONCLUSION

This systematic review is the first that shows how the oral microbiota composition in adolescents appears to differ between those with and without dental caries, suggesting certain taxa may be associated with increased caries risk. However, there is a need to replicate and expand these findings in larger, longitudinal studies that also focus on caries severity and take adolescent-specific factors into account.

Influence of keratinized mucosa width on the resolution of peri-implant mucositis: A prospective cohort study

BACKGROUND

The prevalence of peri-implant diseases, driven by biofilm accumulation and influenced by factors such as the width of keratinized mucosa (KM), underscores the need for understanding their etiology and management.

PURPOSE

To evaluate the association between the KM width and the clinical resolution of peri-implant mucositis after mechanical therapy.

MATERIALS AND METHODS

Patients with an implant diagnosed with peri-implant mucositis were allocated to two groups: wide band of KM (WKM ≥ 2 mm) and narrow/no band of KM (NKM < 2 mm). Data and submucosa biofilm were collected at baseline and at 8, 12, and 24 weeks after nonsurgical therapy. A Brunner-Langer model was estimated for longitudinal data to evaluate and compare changes in any clinical parameter throughout follow-up between both groups. Furthermore, the microbial profiles were evaluated by 16S rRNA gene sequencing.

RESULTS

A total of 38 implants were analyzed. At 24 weeks, bleeding on probing was substantially reduced in both groups, reaching statistical significance (p < 0.001). Treatment resulted in 23.9% less effective in achieving success for NKM. As such, NKM reduced the odds of disease resolution by 80% compared to WKM. The rest of the explored clinical parameters yielded more favorable outcomes for WKM versus NKM. Neither the alpha nor the beta diversity of the microbial profiles were significantly modulated by KM.

CONCLUSIONS

KM width influences the clinical resolution of peri-implant mucositis after mechanical therapy (https://clinicaltrials.gov/study/NCT04874467?cond=keratinized%20mucosa&rank=8, NCT04874467, 04/30/2021).

Comparative 16S rRNA gene sequencing study of subgingival microbiota of healthy subjects and patients with periodontitis from four different countries

AIM

To investigate the differences between the subgingival microbiota of healthy subjects (HS) and periodontitis patients (PP) from four different countries through a metagenomic approach.

MATERIALS AND METHODS

Subgingival samples were obtained from subjects from four different countries. Microbial composition was analysed through high-throughput sequencing of the V3-V4 region of the 16S rRNA gene. The country of origin, diagnosis and clinical and demographic variables of the subjects were used to analyse the microbial profiles.

RESULTS

In total, 506 subgingival samples were analysed: 196 from HS and 310 from patients with periodontitis. Differences in richness, diversity and microbial composition were observed when comparing samples pertaining to different countries of origin and different subject diagnoses. Clinical variables, such as bleeding on probing, did not significantly affect the bacterial composition of the samples. A highly conserved core of microbiota associated with periodontitis was detected, while the microbiota associated with periodontally HS was much more diverse.

CONCLUSIONS

Periodontal diagnosis of the subjects was the main variable explaining the composition of the microbiota in the subgingival niche. Nevertheless, the country of origin also had a significant impact on the microbiota and is therefore an important factor to consider when describing subgingival bacterial communities.

Bacterial Adhesion of TESPSA and Citric Acid on Different Titanium Surfaces Substrate Roughness: An In Vitro Study with a Multispecies Oral Biofilm Model

This in vitro study analyzed the influence of substrate roughness on biofilm adhesion and cellular viability over triethoxysilylpropyl succinic anhydride silane (TESPSA)- and citric acid (CA)-coated surfaces at 12 and 24 h, respectively. A multispecies biofilm composed of S. oralis, A. naslundii, V. parvula, F. nucleatum, P. intermedia, P. gingivalis, P. endodontalis and F. alocis was developed over titanium discs grouped depending on their roughness (low, medium, high) and antibacterial coating (low-TESPSA, medium-TESPSA, high-TESPSA, and CA). The biofilm was quantified by means of quantitative polymerase chain reaction (PCR) and viability PCR and assessed through confocal laser scanning microscope (CLSM). Quantitative PCR revealed no significant differences in bacterial adhesion and biofilm mortality. CA was the surface with the lowest bacterial counts and highest mortality at 12 and 24 h, respectively, while high harbored the highest amount of biofilm at 24 h. By CLSM, CA presented significant amounts of dead cells compared to medium-TESPSA and high-TESPSA. A significantly greater volume of dead cells was found at 12 h in low-TESPSA compared to medium-TESPSA, while CA also presented significant amounts of dead cells compared to medium-TESPSA and high-TESPSA. With regard to the live/dead ratio, low-TESPSA presented a significantly higher ratio at 12 h compared to medium-TESPSA and high-TESPSA. Similarly, CA exhibited a significantly higher live/dead ratio compared to medium-TESPSA and high-TESPSA at 12 h. This multispecies in vitro biofilm did not evidence clear antiadhesive and bactericidal differences between surfaces, although a tendency to reduce adhesion and increase antibacterial effect was observed in the low-TESPSA and CA.

Cetylpyridinium Chloride-Containing Mouthwashes Show Virucidal Activity against Herpes Simplex Virus Type 1

The oral cavity is particularly susceptible to viral infections that are self-recovering in most cases. However, complications may appear in severe cases and/or immunocompromised subjects. Cetylpyridinium chloride (CPC)-containing mouthwashes are able to decrease the infectivity of the SARS-CoV-2 virus by disrupting the integrity of the viral envelope. Here, we show that CPC, as the active ingredient contained in commercialized, exerts significant antiviral activity against enveloped viruses, such as HSV-1, but not against non-enveloped viruses, such as HPV. CPC-containing mouthwashes have been used as antiseptics for decades, and thus, they can represent a cost-effective measure to limit infection and spread of enveloped viruses infecting the oral cavity, aiding in reducing viral transmission.

Microbial profile of placentas from Tanzanian mothers with adverse pregnancy outcomes and periodontitis

AIM

To investigate microbial profiles in placentas from a population of East African mothers with and without adverse pregnancy outcomes and with regard to their periodontal status.

MATERIAL AND METHODS

Thirty-six placentas from pregnant women from Tanzania were classified into three groups according to both pregnancy outcome and the mother's periodontal health. The microbial composition in each group was then compared using 16S rRNA metagenomics. Additionally, placenta specimens were analyzed histologically for chorioamnionitis by a single pathologist blinded to the clinical data.

RESULTS

The greatest differences were observed in the group of mothers with periodontitis. The microbial load was low in all three groups of mothers. Periodontitis had a notable influence on the structure of the placental microbiota. Three phyla and 44 genera were associated with periodontitis, whereas only the Tenericutes phylum was associated with the adverse pregnancy variable. Streptococcaceae and Mycoplasmataceae families were associated with both periodontitis and adverse pregnancy outcomes. Finally, although the differences for chorioamnionitis were not significant, this intra-amniotic infection was more frequent in the placentas from mothers with periodontitis.

CONCLUSIONS

Our findings suggest that bacteria from the oral cavity may involve the feto-placental unit, and that periodontitis may be a modulating factor of the microbial community present in this niche.

The quorum quenching enzyme Aii20J modifies in vitro periodontal biofilm formation

Introduction

Recent studies have revealed the presence of N-acyl-homoserine lactones (AHLs) quorum sensing (QS) signals in the oral environment. Yet, their role in oral biofilm development remains scarcely investigated. The use of quorum quenching (QQ) strategies targeting AHLs has been described as efficient for the control of pathogenic biofilms. Here, we evaluate the use of a highly active AHL-targeting QQ enzyme, Aii20J, to modulate oral biofilm formation in vitro.

Methods

The effect of the QQ enzyme was studied in in vitro multispecies biofilms generated from oral samples taken from healthy donors and patients with periodontal disease. Subgingival samples were used as inocula, aiming to select members of the microbiota of the periodontal pocket niche in the in vitro biofilms. Biofilm formation abilities and microbial composition were studied upon treating the biofilms with the QQ enzyme Aii20J.

Results and Discussion

The addition of the enzyme resulted in significant biofilm mass reductions in 30 - 60% of the subgingival-derived biofilms, although standard AHLs could not be found in the supernatants of the cultured biofilms. Changes in biofilm mass were not accompanied by significant alterations of bacterial relative abundance at the genus level. The investigation of 125 oral supragingival metagenomes and a synthetic subgingival metagenome revealed a surprisingly high abundance and broad distribution of homologous of the AHL synthase HdtS and several protein families of AHL receptors, as well as an enormous presence of QQ enzymes, pointing to the existence of an intricate signaling network in oral biofilms that has been so far unreported, and should be further investigated. Together, our findings support the use of Aii20J to modulate polymicrobial biofilm formation without changing the microbiome structure of the biofilm. Results in this study suggest that AHLs or AHL-like molecules affect oral biofilm formation, encouraging the application of QQ strategies for oral health improvement, and reinforcing the importance of personalized approaches to oral biofilm control.

Association of nine pathobionts with periodontitis in four South American and European countries

Aim

Our aim was to compare the prevalence and load of nine pathobionts in subgingival samples of healthy individuals and periodontitis patients from four different countries.

Methods

Five hundred and seven subgingival biofilm samples were collected from healthy subjects and periodontitis patients in Belgium, Chile, Peru and Spain. The prevalence and load of Eubacterium brachy, Filifactor alocis, Fretibacterium fastidiosum, Porphyromonas endodontalis, Porphyromonas gingivalis, Selenomonas sputigena, Treponema denticola, Tannerella forsythia and Treponema socranskii were measured by quantitative PCR.

Results

The association with periodontitis of all species, except for T. socranskii, was confirmed in all countries but Peru, where only P. endodontalis, P. gingivalis and T. denticola were found to be significantly associated. Moreover, most species showed higher loads at greater CAL and PPD, but not where there was BOP. Through Principal Component Analysis, samples showed clearly different distributions by diagnosis, despite observing a smaller separation in Peruvian samples.

Conclusions

Unlike prevalence, relative load was found to be a reliable variable to discriminate the association of the species with periodontitis. Based on this, F. alocis, P. endodontalis, P. gingivalis, T. denticola and T. forsythia may be biomarkers of disease in Belgium, Chile and Spain, due to their significantly higher abundance in periodontitis patients.

Bacterial decontamination of toothbrushes by immersion in a mouthwash containing 0.05% chlorhexidine and 0.05% cetylpyridinium chloride: A randomized controlled trial

OBJECTIVE

Toothbrushes are colonized by microorganisms, implying a risk of infection. That risk can be reduced by decreasing the microbial contamination of the filaments. Therefore, this study aimed to determine the antiseptic efficacy of a 0.05% chlorhexidine + 0.05% cetylpyridinium chloride mouthwash on toothbrushes.

METHODS

A total of twelve toothbrushes used three times/day for 14 days by orally and systemically healthy people were randomly split into two groups, and their heads were immersed for 2 h in PBS (control) or Perio·Aid Active Control (treatment). The microorganisms were recovered, and their number was calculated by culture, quantitative PCR, and viability PCR. Statistical differences were first assessed with a two-way mixed ANOVA and subsequently with Student's t-test.

RESULTS

The results showed no statistical differences in the total number of cells for the treatment (mean ± CI95% of 7.27 ± 1.09 log₁₀ bacteria/ml) and the control (7.62 ± 0.64 log₁₀ bacteria/ml) groups, but a significantly lower number of live cells in the treatment group (4.58 ± 0.61 log₁₀ viable bacteria/ml and 2.15 ± 1.42 log₁₀ cfu/ml) than in the control group (6.49 ± 1.39 log₁₀ viable bacteria/ml and 5.04 ± 0.93 log₁₀ cfu/ml).

CONCLUSIONS

Based on our findings, sanitization of toothbrushes with this mouthwash reduces the number of live microorganisms adhered to the filaments. Such decrease of the bacterial load could include bacteria from the oral cavity, from the environment, and from nearby toothbrushes since the quantification was not limited to any bacterial taxon.

Cetylpyridinium Chloride Mouthwash to Reduce Shedding of Infectious SARS-CoV-2: A Double-Blind Randomized Clinical Trial

The airborne transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) via respiratory fluids and droplets suggests that mouthwashes containing substances with virucidal activity can help reduce viral spread. We conducted a multicenter, double-blind, placebo-controlled, randomized trial to assess the virucidal activity of cetylpyridinium chloride (CPC) mouthwashes. Outpatients who tested positive for SARS-CoV-2 infection with or without symptoms were randomized to perform washes and gargles for 1 min with 15 mL of either colored distilled water or 0.07% CPC (Vitis CPC Protect) mouthwash. The study outcomes were the SARS-CoV-2 log₁₀ viral RNA load and the nucleocapsid protein levels, both in saliva at 1 and 3 h after the intervention. In total, 118 patients were enrolled and randomized (mean [SD], age 46 [14] y). Thirteen of 118 participants (11%) did not complete follow-up or had insufficient sample volume for testing and were excluded from the analysis. The assessment of the viral load showed no significant differences between groups at any of the investigated points. However, the levels of SARS-CoV-2 nucleocapsid protein of lysed viruses were significantly higher in the CPC group compared with the control group at 1 h (adjusted difference 269.3 pg/mL; 95% confidence interval [CI], 97.1-441.5) and at 3 h postintervention (561.1 pg/mL; 95% CI, 380.0-742.2). In nonhospitalized patients with asymptomatic or mild symptomatic SARS-CoV-2 infection, a 0.07% CPC mouthwash, compared to placebo, was associated with a significant increase of nucleocapsid protein levels in saliva, indicating enhanced disruption of viral particles.

Impact of smoking on peri-implant bleeding on probing

BACKGROUND

Studies around natural dentition demonstrated that smoking can reduce the tendency of inflamed tissue to bleed upon probing after controlling for possible confounders. In addition, previous research suggested that smokers may present alterations of the peri-implant microbiome.

AIM

This study aimed at investigating the impact of smoking on: (1) peri-implant bleeding on probing (BOP; primary objective); (2) the association between BOP/bone loss and BOP/visible gingival inflammation; (3) peri-implant microbiome.

METHODS

Partially edentulous patients with implants restored with a single crowns were included in this study. Subjects were either smokers (≥1 cigarettes per day) or nonsmokers (never smokers). The primary outcome of this cross-sectional study was BOP and secondary outcomes included: Probing pocket depth (PPD), Modified gingival Index (mGI) and Progressive Marginal Bone Loss. In addition, microbial profiles of the subjects were assessed through sequencing of the 16S rRNA gene. Univariate and multilevel multivariate analyses by means of Generalized Estimating Equations were conducted to analyze the association between smoking and peri-implant BOP.

RESULTS

Overall, 27 nonsmokers and 27 smokers were included and 96.3% and 77.78% of patients presented peri-implant BOP in the nonsmoker and smoker group, respectively (p = 0.046). Smoking was inversely associated with BOP in the multivariate multilevel analysis (OR = 0.356; 95% CI: 0.193-0.660; p = 0.001) whereas a positive correlation was demonstrated for mGI > 0 (OR = 3.289; 95% CI: 2.014-5.371; p < 0.001); PPD (OR = 1.692; 95% CI: 0.263-0.883; p = 0.039) and gender (OR = 2.323; 95% CI: 1.310-4.120 p = 0.004). A decrease of BOP sensitivity in detecting visible gingival inflammation (mGI > 0) was observed in smokers. Besides, taxonomic and changes in diversity regarding the peri-implant microbiota were detected comparing the two groups. Significantly higher richness of the microbiota was demonstrated in the smoker group when implants affected by peri-implantitis were compared to either healthy implants or implants presenting mucositis.

CONCLUSIONS

Smoking is a potential modifier of BOP and peri-implant microbiota.

Erythritol-enriched powder and oral biofilm regrowth on dental implants: an in vitro study

Background

Peri-implant mucositis and peri-implantitis are the main biological complications associated with dental implants. Since most authors agree that bacteria play a major etiological role, the main aims of this study were to determine if a formulation of erythritol and chlorhexidine applied with an air polishing system inhibits biofilm regrowth over dental implants and to compare the decontamination capacity of this therapy with that of mechanical removal by saline and gauze.

Material and Methods

A multispecies biofilm (P. gingivalis, A. actinomycetemcomitans, F. nucleatum, A. naeslundii, V. parvula and S. oralis) was grown for 14 days on 52 dental implants in an artificial mouth. These implants were divided into three groups according to the applied treatment: 14 negative control (CON), 19 erythritol-chlorhexidine (ERY) and 19 gauze with saline (GAU) samples. Twelve dental implants from the ERY and GAU groups and 8 implants from the CON group were re-incubated for 7 additional days after treatment. The bacterial count was performed by quantitative polymerase chain reaction (qPCR) using propidium monoazide (PMA). A descriptive and bivariate analysis of the data was performed.

Results

The erythritol and chlorhexidine formulation significantly inhibited biofilm regrowth in comparison with the mechanical treatment (GAU), since a significant decrease in all the species was observed in the ERY group (except for Aggregatibacter actinomycetemcomitans). The antibiofilm and antibacterial capacity of the two active treatment groups (ERY and GAU) was similar for a 14 days multispecies in vitro biofilm, except for the lower count of A. naeslundii in the GAU group.

Conclusions

The use of erythritol powder with chlorhexidine applied with an air polishing system reduces biofilm regrowth over dental implants when compared with mechanical removal by saline and gauze. This effect might be beneficial for patients included in peri-implant maintenance programs.

Key words:Dental implants, biofilms, peri-implantitis, erythritol, chlorhexidine.

Mouthwashes with CPC Reduce the Infectivity of SARS-CoV-2 Variants In Vitro

Oral mouthwashes decrease the infectivity of several respiratory viruses including SARS-CoV-2. However, the precise agents with antiviral activity in these oral rinses and their exact mechanism of action remain unknown. Here we show that cetylpyridinium chloride (CPC), a quaternary ammonium compound in many oral mouthwashes, reduces SARS-CoV-2 infectivity by inhibiting the viral fusion step with target cells after disrupting the integrity of the viral envelope. We also found that CPC-containing mouth rinses decreased more than a thousand times the infectivity of SARS-CoV-2 in vitro, while the corresponding vehicles had no effect. This activity was effective for different SARS-CoV-2 variants, including the B.1.1.7 or Alpha variant originally identified in United Kingdom, and in the presence of sterilized saliva. CPC-containing mouth rinses could therefore represent a cost-effective measure to reduce SARS-CoV-2 infectivity in saliva, aiding to reduce viral transmission from infected individuals regardless of the variants they are infected with.

Tetracycline and multidrug resistance in the oral microbiota: differences between healthy subjects and patients with periodontitis in Spain

Introduction: Antibiotic resistance is widely found even among bacterial populations not having been exposed to selective pressure by antibiotics, such as tetracycline. In this study we analyzed the tetracycline-resistant subgingival microbiota of healthy subjects and of patients with periodontitis, comparing the prevalence of tet genes and their multidrug resistance profiles.

Methods: Samples from 259 volunteers were analyzed, obtaining 813 tetracycline-resistant isolates. The prevalence of 12 antibiotic resistance genes was assessed, and multidrug profiles were built. Each isolate was identified by 16S rRNA sequencing. Differences in qualitative data and quantitative data were evaluated using the chi-square test and the Mann-Whitney-U test, respectively.

Results: tet(M) was the most frequently detected tet gene (52.03%). We observed significant differences between the prevalence of tet(M), tet(W), tet(O), tet(32) and tet(L) in both populations studied. Multidrug resistance was largely observed, with resistance to kanamycin being the most detected (83.64%). There were significant differences between the populations in the prevalence of kanamycin, chloramphenicol, and cefotaxime resistance. Resistant isolates showed significantly different prevalence between the two studied groups.

Conclusion: The high prevalence of multidrug resistance and tetracycline resistance genes found in the subgingival microbiota, highlights the importance of performing wider and more in-depth analysis of antibiotic resistance in the oral microbiota.

Acyl homoserine lactone-mediated quorum sensing in the oral cavity: a paradigm revisited

Acyl homoserine lactones (AHLs), the quorum sensing (QS) signals produced by Gram-negative bacteria, are currently considered to play a minor role in the development of oral biofilm since their production by oral pathogens has not been ascertained thus far. However, we report the presence of AHLs in different oral samples and their production by the oral pathogen Porphyromonas gingivalis. The importance of AHLs is further supported by a very high prevalence of AHL-degradation capability, up to 60%, among bacteria isolated from dental plaque and saliva samples. Furthermore, the wide-spectrum AHL-lactonase Aii20J significantly inhibited oral biofilm formation in different in vitro biofilm models and caused important changes in bacterial composition. Besides, the inhibitory effect of Aii20J on a mixed biofilm of 6 oral pathogens was verified using confocal microscopy. Much more research is needed in order to be able to associate specific AHLs with oral pathologies and to individuate the key actors in AHL-mediated QS processes in dental plaque formation. However, these results indicate a higher relevance of the AHLs in the oral cavity than generally accepted thus far and suggest the potential use of inhibitory strategies against these signals for the prevention and treatment of oral diseases.

Resistance to β-lactams and distribution of β-lactam resistance genes in subgingival microbiota from Spanish patients with periodontitis

OBJECTIVES

The aim of this study was to analyze the distribution of β-lactamase genes and the multidrug resistance profiles in β-lactam-resistant subgingival bacteria from patients with periodontitis.

MATERIALS AND METHODS

Subgingival samples were obtained from 130 Spanish patients with generalized periodontitis stage III or IV. Samples were grown on agar plates with amoxicillin or cefotaxime and incubated in anaerobic and microaerophilic conditions. Isolates were identified to the species level by the sequencing of their 16S rRNA gene. A screening for the following β-lactamase genes was performed by the polymerase chain reaction (PCR) technique: bla_TEM, bla_SHV, bla_CTX-M, bla_CfxA, bla_CepA, bla_CblA, and bla_ampC. Additionally, multidrug resistance to tetracycline, chloramphenicol, streptomycin, erythromycin, and kanamycin was assessed, growing the isolates on agar plates with breakpoint concentrations of each antimicrobial.

RESULTS

β-lactam-resistant isolates were found in 83% of the patients. Seven hundred and thirty-seven isolates from 35 different genera were obtained, with Prevotella and Streptococcus being the most identified genera. bla_CfxA was the gene most detected, being observed in 24.8% of the isolates, followed by bla_TEM (12.9%). Most of the isolates (81.3%) were multidrug-resistant.

CONCLUSIONS

This study shows that β-lactam resistance is widespread among Spanish patients with periodontitis. Furthermore, it suggests that the subgingival commensal microbiota might be a reservoir of multidrug resistance and β-lactamase genes.

CLINICAL RELEVANCE

Most of the samples yielded β-lactam-resistant isolates, and 4 different groups of bla genes were detected among the isolates. Most of the isolates were also multidrug-resistant. The results show that, although β-lactams may still be effective, their future might be hindered by the presence of β-lactam-resistant bacteria and the presence of transferable bla genes.

Detection and expression analysis of tet(B) in Streptococcus oralis

Tetracycline resistance can be achieved through tet genes, which code for efflux pumps, ribosomal protection proteins and inactivation enzymes. Some of these genes have only been described in either Gram-positive or Gram-negative bacteria. This is the case of tet(B), which codes for an efflux pump and, so far, had only been found in Gram-negative bacteria. In this study, tet(B) was detected in two clinical Streptococcus oralis strains isolated from the gingival sulci of two subjects. In both cases, the gene was completely sequenced, yielding 100% shared identity and coverage with other previously published sequences of tet(B). Moreover, we studied the expression of tet(B) using RT-qPCR in the isolates grown with and without tetracycline, detecting constitutive expression in only one of the isolates, with no signs of expression in the other one.

This is the first time that the presence and expression of the tet(B) gene has been confirmed in Gram-positive bacteria, which highlights the potential of the genus Streptococcus to become a reservoir and a disseminator of antibiotic resistance genes in an environment so prone to horizontal gene transfer as is the oral biofilm.

Development and viability of biofilms grown on experimental abutments mimicking dental implants: An in vivo model

BACKGROUND

To determine whether an experimental abutment mimicking the macro- and microstructure of a dental implant is a suitable method for recovering biofilm, and to describe the features of biofilms formed around such abutments on healthy implants.

MATERIAL AND METHODS

Experimental abutments were used in 15 patients without peri-implant diseases. After 14 days' absence of dental hygiene in this area, the abutments were retrieved and analyzed through confocal laser scanning microscopy and scanning electron microscopy. The biofilm formation on the surface of the first 5 abutments was determined by a fluorescence-staining method using SYTO9 nucleic acid stain. In order to study the biofilm's coverage and vitality, 10 additional abutments were assessed using live & dead bacterial viability. Descriptive and bivariate analyses of the data were performed.

RESULTS

A global plaque coverage of the abutments was observed in all cases. The submucosal area of the abutment was mostly covered with biofilm (over 21%). Moreover, significant differences between supra- and subgingival locations were detected.

CONCLUSIONS

This in vivo experimental model allows detailed observation of the extensive plaque growth found on exposed experimental abutments mimicking dental implants when hygiene measures are absent. The biofilm coverage is significantly higher in the supragingival zone than in the subgingival portion.

Azithromycin and erythromycin susceptibility and macrolide resistance genes in Prevotella from patients with periodontal disease

OBJECTIVES

To study oral Prevotella spp. isolated from patients with chronic periodontitis, to determine their susceptibility to azithromycin and erythromycin and to screen the presence of macrolide resistance genes therein.

MATERIAL AND METHODS

Isolates with a Prevotella-like morphology were obtained from subgingival samples of 52 patients with chronic periodontitis. Each isolate was identified to the species level by sequencing of the 16S rRNA gene. In 100 Prevotella spp. isolates, azithromycin and erythromycin susceptibility was determined using the E test method, and the screening of erm(A), erm(B), erm(C), erm(F), erm(G), erm(Q) and mef(A) genes was done by PCR.

RESULTS

Prevotella intermedia and Prevotella nigrescens were the most identified species (33% each). Minimum inhibitory concentrations (MICs) ranges for both antibiotics were 0.016/0.032 to >256 μg/ml. MIC₅₀ values for azithromycin and erythromycin were 1.5 and 1 μg/ml, respectively, and MIC₉₀ values were >256 μg/ml for both antibiotics. Nineteen per cent of the isolates carried erm(B), and 51% carried erm(F).

CONCLUSIONS

The MIC values found were high compared to previous studies. erm(F) was greatly prevalent, and we describe for the first time the erm(B) gene in Prevotella spp. The presence of either of the genes seems to be associated with a higher degree of resistance to azithromycin and erythromycin.

In vitro evaluation of a multispecies oral biofilm over antibacterial coated titanium surfaces

Peri-implantitis is an infectious disease that affects the supporting soft and hard tissues around dental implants and its prevalence is increasing considerably. The development of antibacterial strategies, such as titanium antibacterial-coated surfaces, may be a promising strategy to prevent the onset and progression of peri-implantitis. The aim of this study was to quantify the biofilm adhesion and bacterial cell viability over titanium disc with or without antibacterial surface treatment. Five bacterial strains were used to develop a multispecies oral biofilm. The selected species represent initial (Streptococcus oralis and Actinomyces viscosus), early (Veillonella parvula), secondary (Fusobacterium nucleatum) and late (Porphyromonas gingivalis) colonizers. Bacteria were sequentially inoculated over seven different types of titanium surfaces, combining different roughness level and antibacterial coatings: silver nanoparticles and TESPSA silanization. Biofilm formation, cellular viability and bacterial quantification over each surface were analyzed using scanning electron microscopy, confocal microscopy and real time PCR. Biofilm formation over titanium surfaces with different bacterial morphologies could be observed. TESPSA was able to significantly reduce the cellular viability when compared to all the surfaces (p < 0.05). Silver deposition on titanium surface did not show improved results in terms of biofilm adhesion and cellular viability when compared to its corresponding non-coated surface. The total amount of bacterial biofilm did not significantly differ between groups (p > 0.05). TESPSA was able to reduce biofilm adhesion and cellular viability. However, silver deposition on titanium surface seemed not to confer these antibacterial properties.

Association of periodontitis with preterm birth and low birth weight: a comprehensive review

It is estimated that six million perinatal deaths occur every year worldwide, with premature birth being the main cause. Scientific evidence has shown that there is an association between periodontal health during pregnancy and adverse outcomes of labor, although interventional studies based on the treatment of periodontitis have failed to document an impact on reducing the incidence of preterm birth (PB) or low birth weight (LBW). Two pathogenic mechanisms have been proposed to explain this association. The direct pathway is based on the presence of gram-negative anaerobic bacteremia originating in the gingival biofilm, whereas the indirect pathway involves the production of pro-inflammatory markers which enter the bloodstream from the gingival submucosa. The result is the same: the development of an immune inflammatory response and/or the local suppression of growth factors in the fetal-placental unit, which in turn triggers labor. In the present review, we describe current concepts pertinent to PB and LBW, chronic and aggressive periodontitis, and the most frequent aspects of periodontal pathology during pregnancy. We evaluate the scientific evidence available to date, and offer a detailed description of the two pathways proposed to explain the association of maternal periodontitis with preterm and LBW delivery.

[Clusters of Fusarium solani infection in juvenile captive born Caretta caretta sea turtles]

Various yeasts and filamentous fungi are described as the cause of infection in sea turtles. Among them, Fusarium solani is responsible both for superficial and invasive infection in weakened adults (capture, stranding), and wild nest contamination, causing massive losses during hatching. We illustrate the pathogenicity of this fungus in sea turtles, through our experience with the species Caretta caretta (loggerhead turtle) and its reproduction, which was obtained for the first time in 2010 at the marine park Marineland, Antibes and renewed in 2011 and 2013. The first generation (6 viable newborns e.g. 0.9% of the nest) was severely affected by an infectious agent causing skin and multifocal organ lesions. Microbiological samples allowed to establish F. solani as the etiological agent. Antifungal therapy with posaconazole cured 2 (33%) of the brood. Epidemiological investigations, infection control and hygiene measures as well as diagnosis criteria, preemptive and curative treatment procedures allowed better prevention and cure and finally higher survival rates in subsequent broods, in 2011 and 2013 (80 viable newborns e.g. 6.6% of the nest and 50% survival rate). F. solani appears as a major threat for the successful reproduction of sea turtles in the wild. As observed, this threat is also of concern during captive breeding. The conditions of transmission and pathogenicity of Fusarium spp. in these animals are discussed in light of the literature cases that occurred in adult sea turtles and in wild nests, and of our breeding experience.

Oral bacteria in placental tissues: increased molecular detection in pregnant periodontitis patients

OBJECTIVES

The objective of this study was to identify the DNA of oral bacteria in placental samples from women with and without periodontitis who had or had not had preterm births and/or low birthweight (PB/LBW) neonates.

METHODS

Data were gathered from 57 puerperal women in relation to socio-demographic, gynaecological, and periodontal variables and to placental histomorphology. Fifty-seven biopsies, 28 from mothers with periodontitis, were taken aseptically from preterm placentas (n = 36) and from full-term placentas (n = 21). Total DNA was extracted, and the presence of 15 oral bacteria was assessed using Nested-PCR.

RESULTS

The placentas from women with periodontitis showed a higher prevalence of periodontopathogens compared to those from women without periodontitis (P = 0.009). Samples showed low prevalences of Actinomyces israelii, Parvimonas micra and Tannerella forsythia. An association was found between Eikenella corrodens in placenta and periodontitis (P = 0.002). The most ubiquitous bacterium, Fusobacterium nucleatum, was more prevalent in mothers with periodontitis and PB/LBW (P = 0.033). Porphyromonas gingivalis, Treponema denticola, Prevotella intermedia and Aggregatibacter actinomycetemcomitans were not detected.

CONCLUSIONS

These results, along with previous findings, show that oral bacteria may be normally present in the placenta, however, the levels of certain oral pathogens in the placenta would highly depend on the mother's periodontal state.

Molecular epidemiology of OXA-48-producing Klebsiella pneumoniae in France

We characterized 53 OXA-48-producing Klebsiella pneumoniae (OXA-48-Kp) isolated between 2011 and 2013 in 21 French hospitals. All the isolates were genotyped using MLST and PFGE and the population structure of the species was determined by a nucleotide-based analysis of the entire K. pneumoniae MLST database. Most of the OXA-48-Kp isolates also produced CTX-M-15 and remained susceptible to imipenem and meropenem. The isolates were distributed into 20 STs, of which five were dominant (ST15, ST101, ST147, ST395 and ST405). All the OXA-48-Kp clustered in the major clade of K. pneumoniae KpI.

Method to quantify live and dead cells in multi-species oral biofilm by real-time PCR with propidium monoazide

Real-time PCR (qPCR) is a widely used technique in analysing environmental and clinical microbiological samples. However, its main limitation was its inability to discriminate between live and dead cells.

Recently, propidium monoazide (PMA) together with qPCR has been used to overcome this problem, with good results for different bacterial species in different types of samples.

Our objective was to implement this technique for analysing mortality in multi-species oral biofilms formed in vitro with five oral bacteria: Streptococcus oralis, Streptococcus gordonii, Veillonella parvula, Fusobacterium nucleatum and Prevotella intermedia. We also tested its effectiveness on biofilms treated with an antiseptic solution containing 0.07% w/w cetylpyridinium chloride (CPC).

Standardisation of the qPCR-PMA method was performed on pure, heat-killed planktonic cultures of each species, detecting mortality higher than 4 log in S. oralis, S. gordonii and F. nucleatum and higher than 2 for V. parvula and P. intermedia. We obtained similar results for all species when using CPC.

When we analysed biofilms with qPCR-PMA, we found that the mortality in the non-CPC treated multi-species biofilms was lower than 1 log for all species. After treatment with CPC, the viability reduction was higher than 4 log in S. oralis and S. gordonii, higher than 3 log in F. nucleatum and P. intermedia and approximately 2 in V. parvula.

In short, we standardised the conditions for using qPCR-PMA in 5 oral bacterial species and proved its usefulness for quantification of live and dead cells in multi-species oral biofilms formed in vitro, after use of an antiseptic.

Variability of the fimA gene in Porphyromonas gingivalis isolated from periodontitis and non-periodontitis patients

Objective: The goal of this study was to determine the genetic variability of the fimA gene in Porphyromonas gingivalis isolates from Spanish patients. Study Design: Pooled subgingival samples were taken, processed and cultured in non-selective blood agar medium. Pure cultures of one to six isolates per patient were obtained and PCR and PCR-RFLP were used for fimbrillin gene (fimA) type determination of the extracted genomic (DNA). Results: Two hundred and twenty four Porphyromonas gingivalis isolates from 65 patients were analyzed consisting of 15 non-periodontitis patients (66 isolates) and 50 with periodontitis (158 isolates). Genotype II was the most prevalent (50.9%), while the other types of fimbriae did not exceed fifteen percent of prevalence. Isolates with types II and IV of fimbriae were significantly more prevalent in periodontitis patients than isolates with genotype I. Co-infection was observed in 17.65% of the patients analyzed. Conclusion: The results suggest that in this population Porphyromonas gingivalis with type II of fimbriae are significantly more predominant in periodontitis patients than genotype I.

Key words:Fimbriae, genotype, porphyromonas gingivalis, periodontitis.

Validation of ATP bioluminescence as a tool to assess antimicrobial effects of mouthrinses in an in vitro subgingival-biofilm model

Objectives. The aim of this investigation was to evaluate whether the adenosine triphosphate (ATP) bioluminescence method is an appropriate tool to assess the efficacy of antiseptic mouthrinses in terms of quantitative reductions of total viable microbial counts in mixed biofilm populations in vitro. Study Design. Three mouthrinses, containing respectively, chlorhexidine and cetylpyridinium chloride (CHX/CPC), essential oils (EO) and amine fluoride/stannous fluoride (AFSF), as well as Phosphate Buffered Saline (PBS) used as control, were tested in an in vitro static biofilm model by ATP bioluminescence and compared to culture method. Biofilms were grown on saliva-coated hydroxyapatite disks for 72 hours and then exposed for 1 minute to the mouthrinse or control by immersion. The antibacterial effect of the rinses was tested by analysis of variance. The reliability of the ATP bioluminescence method was assessed by calculating the Pearson correlation coefficients when compared to the viable cell counts obtained by culture. Results. Using ATP bioluminescence, the antimicrobial activity of the tested mouthrinses was demonstrated when compared to the PBS control. The ATP bioluminescence values were significantly correlated (0.769, p<0.001) to the viable cell counts. CHX/CPC and AFSF showed similar antimicrobial activity, although AFSF had a less homogeneous effect, being both more effective than the EO rinse. Conclusion. ATP bioluminescence viability testing may be considered a useful tool to assess the in vitro efficacy of antibacterial compounds. In the proposed model, CHX/CPC and AFSF containing mouthrinses demonstrated superior antimicrobial activity, as compared to EO rinses, in a multispecies biofilm model.

Key words:Biofilm, ATP bioluminescence,mouthrinse, essential oils, chlorhexidine, amine fluoride/stannous fluoride.

Are periodontal bacterial profiles and placental inflammatory infiltrate in pregnancy related to birth outcomes?

BACKGROUND

The aim of this study is to determine whether periodontal clinical parameters, periodontal bacterial profiles, and inflammatory infiltrate in placental chorionic villi are associated with adverse pregnancy results.

METHODS

The authors designed an observational case-control study in 244 postpartum females: mothers with preterm/low-birth weight newborns (n = 91 cases) and mothers with full-term, normal-weight infants (n = 153 controls). Sociodemographic, gynecologic, and periodontal variables were gathered for all participants. Data on placental inflammatory infiltrate in biopsies from 68 cases and 65 controls and the gingival bacterial profile in mothers with periodontitis were gathered, detecting associations with bivariate analyses and constructing a multiple logistic regression model with the number of positive inflammatory cells as the dependent variable.

RESULTS

Periodontal values were significantly worse in cases versus controls. Numbers of leukocyte subsets per square millimeters in maternal and fetal vascular spaces were similar between cases and controls. CD45 in maternal placental space was related to the presence of periodontitis (P = 0.029) but not to case or control group (P = 0.264). The anaerobic and commensal bacterial profile in mothers with periodontitis was similar between the groups.

CONCLUSIONS

Periodontal disease was more severe and a periodontitis diagnosis more frequent in mothers with preterm or low-birth weight versus normal delivery. No differences in anaerobic or commensal bacterial profile were found between mothers with periodontitis in the two groups. Local placental factors, such as the nature of the inflammatory infiltrate and slightly higher expression of cyclooxygenase-2 in the females with these adverse pregnancy outcomes, may be related to a subclinical proinflammatory status that could contribute to triggering premature labor.

[Epidemiology of extended spectrum beta-lactamases (ESBL) Enterobacteriaceae in a General Hospital, South of France, 1999-2007]

PURPOSE OF THE STUDY

The global epidemiology of extended spectrum betalactamases (ESBL) producing Enterobacteriaceae has evolved in recent years with the emergence of a new type of ESBL: CTX-M, mainly in Escherichia coli. These CTX-M type producing Enterobacteriaceae are responsible for both nosocomial and, more recently, community infections, including urinary tract infections. The aim of our work is to study ESBL producing Enterobacteriaceae evolution between 1999 and 2007 in the population from the Centre Hospitalier du Pays-d'Aix (CHPA), a general hospital from South of France.

PATIENTS AND METHODS

ESBL producing strains of Enterobacteriaceae isolated in odd years between 1999 and 2007 from clinical isolates of all origins have been phenotypically identified and their ESBL genotyped. Molecular and epidemiological data from our hospital health-care associated infection committee were analyzed.

RESULTS

Two hundred and sixty-two ESBL producing isolates were studied. Within ESBL producing Enterobacteriaceae, Enterobacter aerogenes was predominant in 1999 (48.7% of isolates), and decreased to 18.8% of isolates in 2007. On the other hand, E. coli, which represented 10.5% of ESBL isolates in 1999, grew up to 37.5% of the isolates in 2007. ESBL prevalence in E. coli increased during this period from 0.3 to 2.5%. Simultaneously, ESBL, predominantly TEM-24 in 1999, were replaced by CTX-M in 2007, among which CTX-M-15 is predominant (88% of CTX-M).

CONCLUSION

Our study confirms a major change in ESBL epidemiology in CHPA, with the emergence of CTX-M type ESBL, mainly CTX-M 15, and an increase of ESBL prevalence in E. coli.

A role for class 3 semaphorins in prostate cancer

BACKGROUND

Class 3 semaphorins are secreted proteins that act as guidance cues for migrating cells via their transmembrane receptors plexins and neuropilins. Semaphorins have a role in cancer affecting tumor progression both directly, and indirectly by affecting angiogenesis.

METHODS

The expression of semaphorins and their receptors in prostate cancer cell lines and tissue was determined by RT-PCR, Western blotting and immunohistochemistry. The effect of Sema3E on prostate cancer cell lines was determined by adhesion assays and transwell migration assays.

RESULTS

Semaphorins and their receptors, plexins and neuropilins, are widely co-expressed in prostate cancer cell lines and tissue with a significant overexpression of Sema3E in tumor tissue. Sema3E affected integrin-mediated adhesion to fibronectin of prostate cancer cells, and inhibited their motility. Expression of Sema3C was upregulated and Sema3A and Sema3E were down regulated in prostate cells by hypoxia, consistent with an additional role for Sema3A and 3E as anti-angiogenic factors in prostate cancer.

CONCLUSIONS

Semaphorin 3E is aberrantly expressed in prostate cancer and affects adhesion and motility of prostate cancer cells, indicating a role for the Sema3E/PlexinD1 signaling pathway in prostate cancer and identifying a new possible target for therapy.

Structure, viability and bacterial kinetics of an in vitro biofilm model using six bacteria from the subgingival microbiota

BACKGROUND AND OBJECTIVE

There are few in vitro models available in the scientific literature for study of the structure, formation and development of the subgingival biofilm. The purpose of this study was to develop and validate an in vitro biofilm model, using representative selected bacteria from the subgingival microbiota.

MATERIAL AND METHODS

Six standard reference strains were used to develop biofilms over sterile ceramic calcium hydroxyapatite discs coated with saliva within the wells of presterilized polystyrene tissue culture plates. The selected species represent initial (Streptococcus oralis and Actinomyces naeslundii), early (Veillonella parvula), secondary (Fusobacterium nucleatum) and late colonizers (Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans). The structure of the biofilm obtained was studied using a vital fluorescence technique in conjunction with confocal laser scanning microscopy. The biofilm bacterial kinetics were studied by terminal restriction fragment length polymorphism analysis.

RESULTS

After 12 h, initial and early colonizers were the first microorganisms detected adhering to the calcium hydroxyapatite discs. The intermediate colonizer F. nucleatum was not detected in the model until 24 h of incubation. Late colonizers A. actinomycetemcomitans and P. gingivalis could be measured inside the biofilm after 48 h. The biofilm reached its steady state between 72 and 96 h after inoculation, with bacterial vitality increasing from the hydroxyapatite surface to the central part of the biofilm.

CONCLUSION

An in vitro biofilm model was developed and validated, demonstrating a pattern of bacterial colonization and maturation similar to the in vivo development of the subgingival biofilm.

Clinical manifestations and outcome of skin infections caused by the community-acquired methicillin-resistant Staphylococcus aureus clone ST80-IV

BACKGROUND

Several Panton-Valentin leukocidin-positive clones of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) are spreading worldwide. The European clone ST80-IV is the main CA-MRSA clone in Europe. There is no reported study of the specific clinical manifestations and outcome of skin infections caused by the clone ST80-IV, using strict definitions of skin diseases.

METHODS

Single-centre observational prospective cohort of S. aureus skin infections caused by the clone ST80-IV.

RESULTS

From November 1999 to October 2009, we diagnosed skin infections due to the clone ST80-IV in 20 patients (median age 28 years, median 27; range 1-66). All the isolates had all the following characteristics: lukPV, etd and edin gene-positive, agr 3 allele, spa-type t044 and ST80. All the isolates were resistant to beta-lactam agents, kanamycin, tetracycline and fusidic acid. During the study period, the 20 patients had the following manifestations: 19 primary abscesses (18 single abscess and one patient with two), eight furuncles, four folliculitis, one case of cellulitis, one wound infection and one felon. Surgical treatment and drainage was required for all the primary abscesses. The infections occurred mainly in the perineal area (50%). No secondary infections occurred in family members. Despite strict hygiene measures, systemic antibiotics and nasal mupirocine, four patients (20%) had recurrent skin infections over a period of a few months to 6 years.

CONCLUSIONS

The CA-MRSA clone ST80-IV is responsible for suppurative skin infections such as furuncles and abscesses, which can recur over a period of several years.