The reduction of nitrate to nitrite by the oral microbiota has been proposed to be important for oral health and results in nitric oxide formation that can improve cardiometabolic conditions. Studies of bacterial composition in subgingival plaque suggest that nitrate-reducing bacteria are associated with periodontal health, but the impact of periodontitis on nitrate-reducing capacity (NRC) and, therefore, nitric oxide availability has not been evaluated. The current study aimed to evaluate how periodontitis affects the NRC of the oral microbiota. First, 16S rRNA sequencing data from five different countries were analyzed, revealing that nitrate-reducing bacteria were significantly lower in subgingival plaque of periodontitis patients compared with healthy individuals (P < 0.05 in all five datasets with n = 20-82 samples per dataset). Secondly, subgingival plaque, saliva, and plasma samples were obtained from 42 periodontitis patients before and after periodontal treatment. The oral NRC was determined in vitro by incubating saliva with 8 mmol/L nitrate (a concentration found in saliva after nitrate-rich vegetable intake) and compared with the NRC of 15 healthy individuals. Salivary NRC was found to be diminished in periodontal patients before treatment (P < 0.05) but recovered to healthy levels 90 days post-treatment. Additionally, the subgingival levels of nitrate-reducing bacteria increased after treatment and correlated negatively with periodontitis-associated bacteria (P < 0.01). No significant effect of periodontal treatment on the baseline saliva and plasma nitrate and nitrite levels was found, indicating that differences in the NRC may only be revealed after nitrate intake. Our results suggest that an impaired NRC in periodontitis could limit dietary nitrate-derived nitric oxide levels, and the effect on systemic health should be explored in future studies.
Humans ; Nitrates ; Nitric Oxide ; Nitrites ; RNA, Ribosomal, 16S/genetics* ; Periodontitis/microbiology* ; Bacteria ; Dental Plaque/microbiology* ; Saliva/microbiology* ; Microbiota/genetics*

The oral microbial community is widely regarded as a latent reservoir of antibiotic resistance genes. This study assessed the molecular epidemiology, susceptibility profile, and resistance mechanisms of 35 methicillin-resistant Staphylococcus epidermidis (MRSE) strains isolated from the dental plaque of a healthy human population. Broth microdilution minimum inhibitory concentrations (MICs) revealed that all the isolates were nonsusceptible to oxacillin and penicillin G. Most of them were also resistant to trimethoprim (65.7%) and erythromycin (54.3%). The resistance to multiple antibiotics was found to be largely due to the acquisition of plasmid-borne genes. The mecA and dfrA genes were found in all the isolates, mostly dfrG (80%), aacA-aphD (20%), aadD (28.6%), aphA3 (22.9%), msrA (5.7%), and the ermC gene (14.3%). Classical mutational mechanisms found in these isolates were mainly efflux pumps such as qacA (31.4%), qacC (25.7%), tetK (17.1%), and norA (8.6%). Multilocus sequence type analysis revealed that sequence type 59 (ST59) strains comprised 71.43% of the typed isolates, and the eBURST algorithm clustered STs into the clonal complex 2-II(CC2-II). The staphyloccoccal cassette chromosome mec (SCCmec) type results showed that 25 (71.43%) were assigned to type IV. Moreover, 88.66% of the isolates were found to harbor six or more biofilm-associated genes. The aap, atlE, embp, sdrF, and IS256 genes were detected in all 35 isolates. This research demonstrates that biofilm-positive multiple-antibiotic-resistant ST59-SCCmec IV S. epidermidis strains exist in the dental plaque of healthy people and may be a potential risk for the transmission of antibiotic resistance.
Anti-Bacterial Agents ; therapeutic use ; Dental Plaque ; microbiology ; Female ; Humans ; Methicillin ; Methicillin-Resistant Staphylococcus aureus ; isolation & purification ; Staphylococcal Infections ; diagnosis ; Staphylococcus epidermidis ; isolation & purification

OBJECTIVETo analyze the whole microbial structure in a case of rampant caries to provide evidence for its prevention and treatment.

METHODSClinical samples including blood, supragingival plaque, plaque in the caries cavity, saliva, and mucosal swabs were collected with the patient's consent. The blood sample was sent for routine immune test, and the others samples were stained using Gram method and cultured for identifying colonies and 16S rRNA sequencing. DNA was extracted from the samples and tested for the main cariogenic bacterium (Streptococcus mutans) with qPCR, and the whole microbial structure was analyzed using DGGE.

RESULTSThe patient had a high levels of IgE and segmented neutrophils in his blood. Streptococci with extremely long chains were found in the saliva samples under microscope. Culture of the samples revealed the highest bacterial concentration in the saliva. The relative content of hemolytic bacterium was detected in the samples, the highest in the caries cavity; C. albicans was the highest in the dental plaque. In addition, 33 bacterial colonies were identified by VITEK system and 16S rDNA sequence phylogenetic analysis, and among them streptococci and Leptotrichia wade were enriched in the dental plaque sample, Streptococcus mutans, Fusobacterium nucleatum, and Streptococcus tigurinus in the caries cavity, and Lactobacillus in the saliva. S. mutans was significantly abundant in the mucosal swabs, saliva and plaque samples of the caries cavity as shown by qPCR. Compared to samples collected from a healthy individual and another two patients with rampant caries, the samples from this case showed a decreased bacterial diversity and increased bacterial abundance shown by PCR-DGGE profiling, and multiple Leptotrichia sp. were detected by gel sequencing.

CONCLUSIONThe outgrowth of such pathogenic microorganisms as S. mutans and Leptotrichia sp., and dysbiosis of oral microbial community might contribute to the pathogenesis of rampant caries in this case.

Abnormalities, Multiple ; Dental Caries ; microbiology ; Dental Plaque ; microbiology ; Fusobacterium ; isolation & purification ; Humans ; Immunoglobulin E ; blood ; Lactobacillus ; isolation & purification ; Leptotrichia ; isolation & purification ; Limb Deformities, Congenital ; Microbiota ; Mouth Mucosa ; microbiology ; Neutrophils ; cytology ; Phylogeny ; Polymerase Chain Reaction ; RNA, Ribosomal, 16S ; genetics ; Saliva ; microbiology ; Streptococcus ; isolation & purification ; Tooth Abnormalities

OBJECTIVETo explore the relationship between the prevalence of Candida albicans and early childhood caries(ECC) among 3-5 years old children of Uygur and Han nationalities in Kashi city, Xinjiang province.

METHODSTotally 397 generally healthy children(Uyghurs 256, Hans141) aged 3-5 years were recruited randomly in Kashi city using the stratified cluster random method. Dental plaque samples were collected from carious tooth tissues of children with ECC and from supragingival tooth sites of caries free(CF) children, respectively. Plaque samples were cultured and Candida albicans were isolated selectively by using CHROM agar candida medium. The isolates were further identified using methods of germ tubes test, Gram stain and PCR molecular biology. The data were analyzed using Pearson χ(2) test and Spearman analysis.

RESULTSThe prevalenses of Candida albicans were 44.5% (114/256) in Han children and 31.2%(44/141) in Urgur children, respectively(P=0.009). Candida albicans could be isolated from 48.8% (124/254) of ECC children, while 23.8% (34/143) of CF ones(P=0.000). The frequencies of Candida albicans acquisition of boys and girls of Uygur children were 51.2%(66/129) and 37.8%(48/127), respectively (P=0.031). The frequencies of Candida albicans acquisition increased with the decayed missing filled tooth (dmft) scores. For both Uygur and Hanchildren, the detection rates of Candida albicans were correlated with dmft scores(Uygur r=0.350, P=0.001; Han r=0.276, P=0.000).

CONCLUSIONSThe oral Candida albicans distributions were different in Uygur and Han ethnic groups. There were significant correlations between the presence of Candida albicans and ECC severityas well as score of dmft. There was a difference of the Candida albicans distributions between boys and girls among Uygur children. Candida albicans might be one of the important cariogenic microorganisms in ECC.

Candida albicans ; isolation & purification ; Candidiasis ; epidemiology ; Child, Preschool ; China ; epidemiology ; Dental Care ; Dental Caries ; epidemiology ; microbiology ; Dental Plaque ; epidemiology ; microbiology ; Ethnic Groups ; statistics & numerical data ; Female ; Humans ; Male ; Prevalence

OBJECTIVETo observe the dynamic changes of membrane-bound proton-translocating ATPase (F-ATPase) in the development of dental caries, the expression of Streptococcus mutans F-ATPase under different pH concentrations and during the development of dental caries is analyzed.

METHODSStreptococcus mutans cultured under different pH (pH4.0-7.0) concentrations and containing 5% glucose and no glucose containing BHI were collected. RNA was extracted. Subsequently, F-ATPase gene was detected using real-time polymerase chain reaction. Male Wistar rats were divided randomly into caries group and control group. The rats in the caries group were fed caries feed and 5% glucose water, whereas those of control group were fed normal feed. Total RNA was extracted from plaque samples, which were collected from rats' oral cavity every two weeks. F-ATPase gene was detected by real-time PCR. In the 11th week, the upper and lower jaw bone specimens of rats were taken, and molar caries damage assessed.

RESULTSThe expression of F-ATPase in the caries group was higher than that in the control group (P<0.05). In addition, the gene was expressed highest in pH5.0 and the lowest in pH4.0 (P<0.05). 2) The expression of F-ATPase progressively increased during the caries development in both groups; expression in the caries group was higher than that in control group (P<0.05).

CONCLUSIONAcid-resisting viru-lence factor F-ATPase is related closely with the incidence and development of dental caries.

Adenosine Triphosphatases ; metabolism ; Animals ; Dental Caries ; metabolism ; microbiology ; Dental Plaque ; microbiology ; Male ; Protons ; Random Allocation ; Rats ; Rats, Wistar ; Real-Time Polymerase Chain Reaction ; Streptococcus mutans ; drug effects ; genetics ; Virulence Factors

Secondary caries due to biofilm acids is a primary cause of dental composite restoration failure. To date, there have been no reports of dental composites that can repel protein adsorption and inhibit bacteria attachment. The objectives of this study were to develop a protein-repellent dental composite by incorporating 2-methacryloyloxyethyl phosphorylcholine (MPC) and to investigate for the first time the effects of MPC mass fraction on protein adsorption, bacteria attachment, biofilm growth, and mechanical properties. Composites were synthesized with 0 (control), 0.75%, 1.5%, 2.25%, 3%, 4.5% and 6% of MPC by mass. A commercial composite was also tested as a control. Mechanical properties were measured in three-point flexure. Protein adsorption onto the composite was determined by the microbicinchoninic acid method. A human saliva microcosm biofilm model was used. Early attachment at 4 h, biofilm at 2 days, live/dead staining and colony-forming units (CFUs) of biofilms grown on the composites were investigated. Composites with MPC of up to 3% had mechanical properties similar to those without MPC and those of the commercial control, whereas 4.5% and 6% MPC decreased the mechanical properties (P<0.05). Increasing MPC from 0 to 3% reduced the protein adsorption on composites (P<0.05). The composite with 3% MPC had protein adsorption that was 1/12 that of the control (P<0.05). Oral bacteria early attachment and biofilm growth were also greatly reduced on the composite with 3% MPC, compared to the control (P<0.05). In conclusion, incorporation of MPC into composites at 3% greatly reduced protein adsorption, bacteria attachment and biofilm CFUs, without compromising mechanical properties. Protein-repellent composites could help to repel bacteria attachment and plaque build-up to reduce secondary caries. The protein-repellent method might be applicable to other dental materials.
Adsorption ; Biofilms ; Colony Count, Microbial ; Composite Resins ; chemistry ; Dental Plaque ; microbiology ; Methacrylates ; analysis ; Phosphorylcholine ; analogs & derivatives ; analysis ; Proteins ; chemistry

OBJECTIVETo establish a systematic method for isolation and identification of aerobic and facultative anaerobic bacteria in the oral cavity.

METHODSSamples of the saliva, dental plaque and periapical granulation tissue were collected from 20 subjects with healthy oral condition and from 8 patients with different oral diseases. The bacteria in the samples were identified by morphological identification, VITEK automatic microorganism identification and 16s rRNA gene sequencing.

RESULTSVITEK automatic microorganism identification and 16s rRNA gene sequencing showed an agreement rate of 22.39% in identifying the bacteria in the samples. We identified altogether 63 bacterial genus (175 species), among which Streptococcus, Actinomyces and Staphylococcus were the most common bacterial genus, and Streptococcus anginosus, Actinomyces oris, Streptococcus mutans and Streptococcus mitis were the most common species. Streptococcus anginosus was commonly found in patients with chronic periapical periodontitis. Streptococcus intermedius and Staphylococcus aureus were common in patients with radiation caries, and in patients with rampant caries, Streptococcus mutans was found at considerably higher rate than other species.

CONCLUSIONAerobic and facultative anaerobic bacteria are commonly found in the oral cavity, and most of them are gram-positive. 16s rRNA gene sequencing is more accurate than VITEK automatic microorganism identification in identifying the bacteria.

Actinomyces ; isolation & purification ; Dental Caries ; Dental Plaque ; microbiology ; Humans ; Mouth ; microbiology ; RNA, Ribosomal, 16S ; genetics ; Saliva ; microbiology ; Staphylococcus aureus ; isolation & purification ; Streptococcus ; isolation & purification

OBJECTIVETo determine the effects of Ginkgo biloba extract (EGB) on major periodontal pathogens in subgingival plaque.

METHODSSixty patients with moderate to severe periodontitis were selected and randomly assigned to 3 groups: EGB group, a positive (periocline) and a negative control groups. Subgingival plaque samples were collected before treatment and 1 week, 2 months and 4 months after treatment. The detection rates of 4 major periodontal pathogens-Treponema denticola (Td), Tannerella forsythus (Tf), Prevotella intermedia (Pi), and Porphyromonas gingivalis (Pg)-were detected by polymerase chain reaction (PCR). Clinical indicators were examined before treatment, 3 and 6 months after treatment.

RESULTSEGB significantly decreased the detection rate of all the 4 pathogens 1 week after treatment, and then gradually increased at 2 and 4 months. EGB's inhibition effect was better than or comparable to periocline, except for Pg in short-term. The difference of plaque index (PLI) and bleeding index (BI) was not statistically significant among the groups, while for probing depth (PD) and attachment loss (AL), the difference was statistically significant between the EGB group and negative control group at 3 and 6 months after treatment.

CONCLUSIONEGB significantly inhibited major periodontal pathogens and can be used as an adjuvant for periodontitis treatment.

Adjuvants, Pharmaceutic ; pharmacology ; therapeutic use ; Bacteria ; drug effects ; isolation & purification ; Dental Plaque ; drug therapy ; microbiology ; Follow-Up Studies ; Ginkgo biloba ; chemistry ; Humans ; Periodontium ; drug effects ; microbiology ; pathology ; Plant Extracts ; pharmacology ; therapeutic use ; Polymerase Chain Reaction ; Treatment Outcome

OBJECTIVEThis study aims to evaluate the antimicrobial activity of decapeptide, a novel antimicrobial peptide, against several major cariogenic and periodontopathogenic bacteria in vitro. METHODS In this study, we investigated the antimicrobial activity of decapeptide against Streptococcus mutans (S. mutans), Streptococcus sobrinus, Lactobacillus acidophilus, Streptococcus sanguis, Streptococcus gordonii, Actinomyces viscosus, Actinomyces naeslundii, Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Actinobacillus actinomycetemcomitans, and Saccharomyces albicans in vitro using the agar diffusion method and broth dilution method. Furthermore, a time-kill kinetic study of decapeptide against S. mutans was performed.

RESULTSThe results showed that decapeptide exhibited antimicrobial activity against various oral bacteria and fungi. The minimum inhibitory concentration (MIC) of main cariogenic bacteria ranged from 62.5 μg · mL(-1) to 125 μg · mL(-1), and the MIC of periodontopathogenic bacteria tested ranged from 250 μg · mL(-1) to 1,000 μg · mL(-1). Among the bacteria tested, decapeptide had a strong inhibitory effect on cariogenic S. mutans. Results of the time-kill kinetic studies showed that decapeptide reduced the viable counts of S. mutans by more than one order of magnitude after 20 min of incubation, and thoroughly killed S. mutans after 30 min. No viable cells could be detected after 24 h of incubation.

CONCLUSIONThis study suggest that decapeptide might have potential clinical application in treating dental caries by killing S. mutans within dental plaque.

Aggregatibacter actinomycetemcomitans ; Anti-Bacterial Agents ; Anti-Infective Agents ; Bacteria ; Dental Caries ; Dental Plaque ; Kinetics ; Microbial Sensitivity Tests ; Mouth ; microbiology ; Porphyromonas gingivalis ; Streptococcus mutans

OBJECTIVETo analyze horizontal transmission patterns of Streptococcus mutans among caries-active preschool children for early interventions of dental caries.

METHODSPlaque samples obtained from 20 caries-active preschool children between 4 and 5 years of age were cultured under anaerobic conditions for isolating S. mutans, which were identified by morphological and biochemical analyses and PCR using primers homologous to the surface protein glucosyltransferase B (gtfB). The genotypes of the isolated S. mutans strains were determined by arbitrarily primed PCR (AP-PCR).

RESULTSOf the 200 S. mutans isolates obtained, 19 were excluded by biochemical analysis, and the remaining 181 isolates were identified as S. mutans by PCR with primers of gtfB, showing 37 different genotypes as identified by AP-PCR. Six children were found to carry S. mutans of a single genotype, 11 carried 2 genotypes, 2 had 3 genotypes, and 1 had 4 genotypes; 2 children from different classes were found to carry S. mutans of the same single genotype.

CONCLUSIONWe identified 37 genotypes of S. mutans in these caries-active preschool children, among whom horizontal transmissions of the strains were not found.

Child, Preschool ; Dental Caries ; microbiology ; Dental Plaque ; Genotype ; Glucosyltransferases ; Humans ; Polymerase Chain Reaction ; Streptococcal Infections ; transmission ; Streptococcus mutans ; classification