Inhibitory effect of Weissella cibaria isolates on the production of volatile sulphur compounds

AIMS: The objective of this study was to characterize the inhibitory effects of Weissella cibaria isolates on volatile sulphur compounds (VSC) production both in vitro and in vivo. MATERIAL AND METHODS: We isolated and identified three hydrogen peroxide-generating lactobacilli from children's saliva, and assessed their inhibitory effects on VSC production and Fusobacterium nucleatum proliferation. Clinical studies were conducted with 46 subjects in order to measure the VSC of their mouth air. RESULTS: These lactobacilli were identified as W. cibaria. These isolates inhibited the production of VSC by F. nucleatum (p<0.05). The concentration of F. nucleatum was decreased by 5-log cycles as a result of exposure to the W. cibaria strains (p<0.05), whereas the catalase-treated W. cibaria cultures exerted no evident inhibitory effects on F. nucleatum replication. In the clinical studies, gargling with one isolate resulted in a significant reduction in the levels of H2S and CH3SH by approximately 48.2% (p<0.01) and 59.4% (p<0.05), respectively. CONCLUSIONS: These results indicate that W. cibaria isolates possess the ability to inhibit VSC production under both in vitro and in vivo conditions, demonstrating that they bear the potential for development into novel probiotics for use in the oral cavity.     

维吾尔族不同龋敏感儿童变链菌临床分离株生物膜状态合成胞外多糖能力的比较

目的:比较维吾尔族高龋和无龋儿童变链菌临床分离株在生物膜状态下合成胞外多糖的能力,以推测其致龋能力的差异。方法:1)选取课题组前期分离鉴定的维吾尔族儿童变链菌临床株27株,其中高龋(dmft≥5)17株,无龋(dmft=0)10株。2)在0.8cm×0.8cm无菌盖玻片上形成变形链球菌生物膜标本。3)采用蒽酮法测定高龋组与无龋组生物膜状态下合成胞外多糖的量。结果:高龋组合成水溶性及水不溶性葡聚糖量平均为(0.3011±0.0398)g/L和(0.3711±0.0372)g/L,高于无龋组的(0.2067±0.0265)g/L和(0.3489±0.0537)g/L,差异有统计学意义(P<0.05)。高龋及无龋组变链菌临床菌株生物膜状态下合成水不溶性葡聚糖量为(0.3656±0.0459)g/L高于水溶性葡聚糖量(0.2539±0.0586)g/L,差异有统计学意义(P<0.05)。结论:维吾尔族不同龋敏感儿童变链菌临床分离株生物膜状态下合成胞外多糖能力有差异,推测与其致龋性差异有关。     

In vitro effects of crude khat extracts on the growth, colonization, and glucosyltransferases of Streptococcus mutans

Millions of Yemenites, East Africans, and immigrants to Western countries chew khat daily for its amphetamine-like effects. There is little information in the literature concerning the possible effects of the habit on oral microbiota. Our objective was to study in vitro crude khat extract effects on Streptococcus mutans growth and sucrose-dependent colonization, and on its glucosyltransferase (GTF) activity and production. Three khat cultivars were used. Lyophilized crude aqueous khat extracts were applied to the different assays at concentrations of 0-1% (w/v). Sucrose-dependent colonization was assessed as the ability of Streptococcus mutans UA159 to form adherent biofilms in glass culture tubes. Colony forming units (CFUs) in the planktonic phase served as a measure of bacterial growth, while CFUs in the biofilm phase were used to quantify viability in the biofilms. GTFs activity was tested by incubating a crude GTFs preparation with sucrose and determining the amount of water-soluble and water-insoluble glucans formed. GTFs production was assayed by comparing intensities of GTF bands in Western blots of extracts from control and khat-containing cultures. The khat extracts effectively inhibited biofilm formation. The minimum biofilm inhibitory concentration (MBIC) varied among the cultivars (0.25-1%). The extracts also inhibited synthesis of both glucan types, particularly insoluble glucans (average 85% inhibition at 1%), with significant differences among the cultivars. However, khat increased bacterial growth and at sub-MBIC also viability within biofilms; there were no inter-cultivar differences. It is shown that khat leaves contain water-soluble constituents that inhibit some cariogenic properties of S. mutans in vitro.     

The effect of cocoa polyphenols on the growth, metabolism, and biofilm formation by Streptococcus mutans and Streptococcus sanguinis

The aim of this study was to determine if cocoa polyphenols could interfere with biofilm formation by Streptococcus mutans or Streptococcus sanguinis, and reduce acid production from sucrose by S. mutans. The antimicrobial activity of cocoa polyphenols was assessed against cariogenic (S. mutans) and health-associated (S. sanguinis) species by minimum inhibitory concentration assays. Cocoa polyphenol dimer, tetramer, and pentamer inhibited the growth of S. sanguinis, whereas the growth of S. mutans was unaffected. However, pretreatment of surfaces with cocoa polyphenol pentamer (35 microM) reduced biofilm formation by S. mutans at 4 and 24 h, whereas the effects on S. sanguinis were less consistent. In contrast, brief exposure of preformed biofilms to pentamer either had no significant effect or resulted in increased counts of S. mutans under certain conditions. Cocoa polyphenol pentamer (500 microM) significantly reduced the terminal pH, and inhibited the rate of acid production by S. mutans at pH 7.0. In conclusion, cocoa polyphenols can reduce biofilm formation by S. mutans and S. sanguinis, and inhibit acid production by S. mutans.     

The cariogenic characters of xylitol-resistant and xylitol-sensitive Streptococcus mutans in biofilm formation with salivary bacteria

Streptococcus mutans metabolize carbohydrates, such as glucose and sucrose, to produce acid and enhance biofilm formation with the early colonizing bacteria to induce dental caries. Xylitol has been used as a reliable substitute for carbohydrate to inhibit the acid production of S. mutans. However, long-term xylitol consumption leads to the emergence of xylitol-resistance in S. mutans. The aim of this study was to investigate the cariogenic trait of Xylitol-resistant (X(R)) S. mutans using biofilm formation and coaggregation of xylitol-sensitive (X(S)) and X(R) S. mutans with salivary bacteria and their glucosyltransferases expression. When X(S) or X(R) S. mutans were incubated in brain heart infusion broth with bacteria from human saliva, X(R)S. mutans exhibited reduction in biofilm formation in comparison to X(S) S. mutans. The coaggregation between X(R) S. mutans and S, gordonii, S. mitis, S. oralis or S. sanguinis was less pronounced than that of X(S) S. mutans in the presence of sucrose. However, there was no difference in the coaggregation between X(R) and X(S) S. mutans in the sucrose-free condition. The level of gtfB and gtfC mRNA expression of X(R) S. mutans was lower than that of X(S) S. mutans, whilst the level of gtfD mRNA expression did not differ between the two strains. The reduction of biofilm formation in X(S) S. mutans due to decrease in glucosyltransferases expression suggests that X(R) S. mutans may be less cariogenic than X(S) S. mutans.     

Effects of commonly used food preservatives on biofilm formation of Streptococcus mutans in vitro

OBJECTIVE: Sodium benzoate (SB), potassium sorbate (PS) and sodium nitrite (SN) are commonly used food preservatives. In this in vitro study, the effects of these substances on biofilm formation of Streptococcus mutans were analysed. METHODS: In addition to the microtiter plate test (MPT), a biofilm reactor containing bovine enamel slabs (BES) was used to study the influence of food preservatives on biofilm formation in 5 independent periods of 4 days each. These included one period with chlorhexidine digluconate (CHX) as a positive control as well as a period with growth medium alone as a negative control. The vitality of the biofilm on BES was detected using live/dead staining and confocal laser scanning microscopy. Additionally, the number of colony forming units (CFU) was determined. RESULTS: In MPT 0.12% SN significantly reduced the biofilm formation. PS at a concentration of 0.4% tended to inhibit biofilm formation, whereas the inhibition for 0.8% PS was significant. Less inhibition was caused by 0.8% SB. In the biofilm reactor 0.06% of SN, 0.1% of SB and 0.1% PS significantly reduced the covering grade as well as the CFU of the biofilm. Biofilm vitality was reduced significantly by CHX to a level of 32.5% compared to the control. Only SB reduced the vitality to a level of 19.1%. SN and PS showed no influence on biofilm vitality. CONCLUSION: This study indicates the potential of food preservatives as inhibitory agents in S. mutans biofilm formation, which should be kept in mind when studying the effects of conserved food on dental plaque biofilm in situ.     

变异链球菌luxS基因对牙菌斑生物膜形成的影响研究

目的敲除变异链球菌中的luxS基因,构建luxS突变株,测试变异链球菌失去luxS基因后形成牙菌斑生物膜的能力。方法把luxS基因敲除重组质粒转入变异链球菌UA159中,得到转化菌,在含有卡拉霉素的培养基中进行筛选,得到变异链球菌luxS基因突变株,并利用聚合酶链式反应（PCR）和哈氏弧菌发光实验对变异链球菌luxS突变株进行检测,通过扫描电镜,对不同时间段变异链球菌luxS突变株和变异链球菌UA159在BHIS培养液（含1%蔗糖的脑心浸液）和BHIG培养液（含1%葡萄糖的脑心浸液）中形成的生物膜进行比较。结果成功的构建了变异链球菌luxS突变株,在BHIS培养液中,变异链球菌luxS突变株形成生物膜的能力比变异链球菌UA159弱,而在BHIG培养液中,二者无显著差异。结论变异链球菌luxS基因对牙菌斑生物膜的形成有重要的影响,并且luxS基因对变异链球菌生物膜的调控是蔗糖依赖型的。     

Effect of nicotine on growth and metabolism of Streptococcus mutans

Streptococcus mutans is a key contributor to dental caries. Smokers have a higher number of caries-affected teeth than do nonsmokers, but the association among tobacco, nicotine, caries, and S. mutans growth has not been investigated in detail. Seven S. mutans strains--UA159, UA130, 10449, A32-2, NG8, LM7, and OMZ175--were used in the present study. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), minimum biofilm inhibitory concentration (MBIC), planktonic cell growth, biofilm formation, metabolism, and structure (determined using scanning electron microscopy) of the seven strains treated with different concentrations of nicotine (0-32 mg ml(-1)) were investigated. The MIC, MBC, and MBIC were 16 mg ml(-1) (0.1 M), 32 mg ml(-1) (0.2 M), and 16 mg ml(-1) (0.1 M), respectively, for most of the S. mutans strains. Growth of planktonic S. mutans cells was significantly repressed by 2.0-8.0 mg ml(-1) of nicotine. Biofilm formation and metabolic activity of S. mutans was increased in a nicotine-dependent manner up to 16.0 mg ml(-1) of nicotine. Scanning electron microscopy revealed that S. mutans treated with a high concentration of nicotine a had thicker biofilm and more spherical bacterial cells. In summary, nicotine enhances S. mutans biofilm formation and biofilm metabolic activity. These results suggest that smoking can increase the development of caries by fostering increased formation of S. mutans biofilm on tooth surfaces.     

Differences between normal and demineralized dentine pretreated with silver fluoride and potassium iodide after an in vitro challenge by Streptococcus mutans

BACKGROUND: The application of diamine silver fluoride (Ag(NH3)2F) and potassium iodide (KI) to demineralized dentine has been shown to inhibit the growth of Streptococcus mutans. The purpose of this study was to observe the differences between demineralized and non-demineralized dentine treated with AgF/KI. METHODS: Thirty-five dentine discs were bonded to the bases of 5 mL polycarbonate screw top vials which were filled with nutrient medium, sterilized and placed into the overflow from a continuous culture of S. mutans. Samples were divided as follows: 10 samples of demineralized dentine; 10 samples of demineralized dentine treated with AgF/KI; 5 samples of non-demineralized dentine; and 10 samples of non-demineralized dentine treated with AgF/KI. Following two weeks connected to the Chemostat, an electron probe microanalysis (EPMA) of percentage weights and penetration depths of calcium, phosphorous silver and fluoride was conducted. Bacterial growth was monitored by taking optical density readings of the growth medium in each vial and outer surfaces of the specimens were examined by scanning electron microscopy (SEM). RESULTS: AgF/KI treatment of demineralized and non-demineralized dentine prevented biofilm formation and reduced further demineralization by S. mutans. AgF/KI treatment of demineralized dentine was more effective in reducing dentine breakdown and the growth of S. mutans. Significantly higher levels of silver and fluoride were deposited within demineralized dentine. CONCLUSIONS: A topical treatment with AgF/KI on dentine reduced in vitro caries development and inhibited surface biofilm formation. Reduction of in vitro caries development and viability of S. mutans was more pronounced on the dentine samples that had been demineralized prior to the application of     

呋喃C-30对变异链球菌生物膜早期形成的影响

目的：探讨密度感应拮抗剂呋喃C-30对变异链球菌生物膜早期形成的影响。方法：将体外合成的密度感应拮抗剂呋喃C-30按终浓度10、100μmol/L分别配制于含变异链球菌的牛心脑浸液培养基,37℃微需氧培养24h,形成生物膜后,用生物膜定量分析仪检测生物膜形成的量。结果：100μmol/L呋喃C-30组变异链球菌生物膜的形成受到显著抑制,磁珠成像开始减弱和完全消失的时间均迟于对照组;生物膜开始形成后,其生物膜形成指数低于对照组,差异有统计学意义（P〈0.05）。结论：呋喃C-30在100μmol/L浓度时能有效抑制变异链球菌生物膜的形成,其应用可能为龋病防治提供新的思路。     

Involvement of antigen I/II surface proteins in Streptococcus mutans and Streptococcus intermedius biofilm formation

BACKGROUND/AIM: Dental diseases are caused by microorganisms organized in biofilms. Streptococcus mutans and Streptococcus intermedius are commensals of the human oral cavity. S. mutans is associated with caries, whereas S. intermedius is associated with purulent infections. Oral streptococci including S. mutants and S. intermedius express a family of surface proteins termed antigen I/II (Ag I/II). Ag I/II is implicated in adhesion; however, its role in biofilm formation has not yet been investigated. METHODS: By using isogenic Ag I/II-deficient mutants of S. mutans and S. intermedius we studied the influence of Ag I/II on in vitro biofilm formation. Biofilm was quantified in polystyrene microtiter plates and visualized by scanning electron microscopy. Ag I/II expression in planktonic and biofilm cells, as well as in the presence or absence of saliva was investigated by immunoblotting. RESULTS: In the presence of saliva, the Ag I/II-deficient mutants formed 65% less biofilm than the wild-types. In the absence of saliva, no difference was observed in S. mutans, whereas the S. intermedius Ag I/II mutant formed 41% less biofilm. Ag I/II expression was reduced in the presence of saliva. No differences in expression were observed between biofilm and planktonic cells. CONCLUSION: The results indicated that Ag I/II may be important during biofilm formation particularly in the presence of saliva. These findings may provide useful information regarding the importance of Ag I/II in biofilm formation and in the search of new strategies to control biofilm-mediated infections.     

姜黄素对变形链球菌UA159生长、粘附的体外实验研究

目的：探索姜黄素对变形链球菌UA159的抗菌能力及姜黄素对变形链球菌UAl59生物膜形成的影响。方法：微量肉汤稀释法检测姜黄素对变形链球菌的最低抑菌浓度（MIC）。分光光度计分析在抑菌浓度范围内姜黄素对变形链球菌生物膜形成的变化。结果：MIC法测得的姜黄素对变形链球菌的抑菌浓度为128wM,而15μM姜黄素即可显示出抑制变形链球菌生物膜形成的特性,且随着姜黄素浓度增加,抑制能力加强。结论：姜黄素具有抑制变形链球菌生物膜形成的特性,且该抑制能力不是建立在抑制变形链球菌生长基础上的。姜黄素可能成为龋病防治的新试剂。     

The effects of orthodontic bonding steps on biofilm formation of Streptococcus mutans in the presence of saliva

Abstract Objective. To investigate the effects of various orthodontic bonding steps on biofilm formation of Streptococcus mutans in the presence of saliva. Materials and methods: Hydroxyapatite (HA) and orthodontic adhesive (AD) disks were prepared to a uniform size. HA disks were etched with 37% phosphoric acid gel in the etched group (HE). In the primed group (HP), Transbond XT primer was applied to the etched HA surface and light-cured. For biofilm formation, Streptococcus mutans was grown on each specimen in a biofilm medium with either glucose or sucrose in the presence of fluid-phase UWS (F-UWS) or surface adsorbed saliva (S-UWS). The adherent bacteria were quantified by enumeration of the total viable counts of bacteria. Biofilms formed on each surface were examined by scanning electron microscopy. Results. When glucose was used, both F-UWS and S-UWS suppressed biofilm formation of S. mutans. Compared to HA and HE, biofilm formation was significantly inhibited on HP and AD in the presence of glucose. Biofilm-forming patterns that were inhibited by saliva were restored in a sucrose-containing medium. F-UWS promoted biofilm formation on HA and HE, while S-UWS significantly promoted biofilm formation on HP. S. mutans developed biofilm better on HA and HE than on AD when sucrose was used as the sole carbohydrate source. Conclusions. This study suggests that the biofilm development by S. mutans is significantly influenced by the orthodontic bonding procedure. Biofilm formation of S. mutans was inhibited on AD more than other surfaces, irrespective of the presence of saliva or a carbohydrate source.     

不同pH对变异链球菌体外生物膜形成的影响

目的：了解变异链球菌临床株体外生物膜形成规律以及不同pH对生物膜形成的影响。方法：采用微孔板培养,染色、分光光度测定法（A630）绘制体外不同pH条件下（pH=7.0～5.0）593号、18号菌株以及变异链球菌标准株（ATCC25175）的生物膜生长曲线。结果：体外变异链球菌各株在pH=5.0时均不能形成生物膜;pH=7.0时细菌生物膜形成表现为缓慢的非线性生长,12～24h生物膜开始成熟,24～36h出现一相对的生长停滞期;pH=5.0时对已形成12h的变链菌生物膜生长有明显的抑制作用,但经历12h的酸休克后各菌株的生物膜均能恢复生长。结论：变异链球菌在体外pH=7.0时于12～24h形成稳定的生物膜,该生物膜能抵抗一定程度的酸（pH=5.0）攻击,而浮游状态的细菌则不能。     

Assessment of gene associated with Streptococcus mutans biofilm formation

Streptococcus mutans, the primary etiological agent of human dental caries and an obligate biofilm-forming bacterium, has developed a variety of mechanisms to colonize the tooth surface. Oral transmission of S. mutans through contact between mother and child is thought to be one of the risks of developing dental caries. In this study, I surveyed oral transmission frequency of S. mutans from mother to a 3-year-old child. In 19 (10.9%) of 174 mother-child pairs, S. mutans was isolated from both mother and chihld. The identities of genomic DNA from S. mutans in 5 (45.5%) of the 11 mother-child pairs were presented. Among those, the biofilms formed by S. mutans 3 c and 4 c, respectively, which had high and low ability of biofilm formation, were examined by confocal laser scanning microscopy (CLSM). Microscopic analysis revealed that the volume of biofilm formation in 3 c was higher than that in 4 c biofilm in the bottom. Furthermore, DNA microarrays were used to study the gene expression profiles of 3 c and 4 c biofilms. In this paper we describe that about 3.8% of genes showed differential expression; about 2.2% of genes were activated and about 1.6% were repressed in 3 c biofilm compared with 4 c biofilm. The present study suggests that biofilm gene expression is strongly associated with differential biofilm formation. Our identification of biofilm-involved genes points to mechanisms of the virulence of S. mutans and provides a first foothold for studying the natural history of S. mutans infections in mother and child.     

Saliva-promoted adhesion of Streptococcus mutans MT8148 associates with dental plaque and caries experience

Colonization of enamel surfaces by Streptococcus mutans is thought to be initiated by the attachment of bacteria to a saliva-derived conditioning film (acquired pellicle). However, the clinical relevance of the contribution of saliva-promoted S. mutans adhesion in biofilm formation has not yet been fully elucidated. The aim of this study was to correlate saliva-promoted S. mutans adhesion with biofilm formation in humans. We correlated all measurements of salivary factors and dental plaque formation in 70 healthy subjects. Dental plaque development after thorough professional teeth cleaning correlated positively with S. mutans adhesion onto saliva-coated hydroxyapatite pellets and the glycoprotein content of either parotid or whole saliva. Saliva-promoted S. mutans adhesion and glycoprotein content were also positively correlated with each other in parotid and whole saliva. By contrast, neither salivary mutans streptococci, Lactobacillus nor Candida correlated with biofilm formation. Parotid saliva-mediated S. mutans adhesion was significantly higher in 12 caries-experienced (CE) subjects than in 9 caries-inexperienced (CI) subjects. Salivary S. mutans adhesion was significantly less (p < 0.01) in the CI group than in the CE group. In conclusion, the present findings suggest the initial S. mutans adhesion, modulated by salivary protein adsorption onto the enamel surface, as a possible correlate of susceptibility to dental plaque and caries.     

Effects of oral streptococci on biofilm formation by cariogenic bacteria in dual species cultures

The effects of oral commensal streptococci (Streptococcus sanguinis, Streptococcus gordonii, Streptococcus mitis, and Streptococcus salivarius) on biofilm formation by cariogenic mutans streptococci (Streptococcus mutans and Streptococcus sobrinus) were investigated. Cell suspensions were cultured on 96-well microtiter plates coated with or without salivary components (SC), and in flow cell systems coated with SC in tryptic soy broth including 0.25% sucrose without dextrose (TSB). The resultant biofilm formations were stained using safranin or a LIVE/DEAD BacLight Viability Kit, and examined with absorbance at 492 nm or using confocal laser scanning microscopy. Mutans streptococci and S. sanguinis biofilms were formed significantly on the polystyrene surfaces in TSB. Further, in combination cultures, S. sanguinis formed a sufficient biofilm when cultured with S. mutans. However, when S. sanguinis was cultured with S. sobrinus, biofilm formation was slightly inhibited. S. gordonii also inhibited biofilm formation in the culture with S. sobrinus, but not when cultured with S. mutans. S. mitis and S. salivarius collapsed the biofilm morphology and inhibited volume development in some conditions when cultured with S. mutans or S. sobrinus. Biofilm formation by mutans streptococci was challenged and collapsed on the whole by culturing with each of the other oral streptococci. These results indicate that co-culturing of multiple species of mutans streptococci and other oral streptococci has physical effects related to previous attachment and colonization on the surface, as well as biological effects to regulate biofilm formation.     

Deletion of gtfC of Streptococcus mutans has no influence on the composition of a mixed-species in vitro biofilm model of supragingival plaque

Glucosyltransferases from Streptococcus mutans are thought to play an important role in bacterial adherence to the tooth surface. The goal of the present study was to determine the effect of the deletion of the gtfC gene, which encodes a glucosyltransferase that catalyses primarily the formation of insoluble glucan (mutan), on colonization of S. mutans in a mixed-species biofilm model of supragingival plaque. A gtfC deletion mutant of S. mutans UA159 grew poorly in biofilms on a polystyrene surface in Todd–Hewitt medium containing sucrose, but biofilm formation in the semi-defined fluid universal medium (FUM) was not affected. The S. mutans gtfC mutant colonized with the same efficiency as the wild-type strain when grown together with five other species in a mixed-species biofilm on hydroxyapatite in a mixture of FUM and saliva with pulses of sucrose and showed the same ability to demineralize enamel in vitro . Colonization of mutant and wild-type strains was also equal in an association experiment in specific-pathogen-free rats. However, the gtfC mutant gave rise to more dentinal fissure lesions and smooth surface caries than the wild-type strain; this could be caused by a change in diffusion properties as a result of to the lack of mutan.     

Clotrimazole and econazole inhibit Streptococcus mutans biofilm and virulence in vitro

Objective: The aim of this study was to determine the inhibitory effect of eight antifungal drugs on S. mutans growth, biofilm formation and virulence factors.MethodsThe actions of antifungal drugs on S. mutans were determined by recovery plates and survival kinetic curves. Biofilms were observed by scanning electron microscopy and the viable cells were recovered on BHI plates, meanwhile biofilms were stained by BacLight live/dead kit to investigate the biofilm viability. Bacteria/extracellular polysaccharides staining assays were performed to determine the EPS production of S. mutans biofilms. Acidogenicity and acidurity of S. mutans were determined using pH drop and acid tolerance assays, and the expression of ldh gene was evaluated using qPCR.ResultsWe found that clotrimazole (CTR) and econazole (ECO) showed antibacterial activities on S. mutans UA159 and S. mutans clinical isolates at 12.5 and 25 mg/L, respectively. CTR and ECO could also inhibit S. mutans biofilm formation and reduce the viability of preformed biofilm. CTR and ECO affected the live/dead ratio and the EPS/bacteria ratio of S. mutans biofilms. CTR and ECO also inhibited the pH drop, lactate acid production, and acid tolerance. The abilities of CTR and ECO to inhibit S. mutans ldh expression were also confirmed.ConclusionsWe found that two antifungal azoles, CTR and ECO, had the abilities to inhibit the growth and biofilm formation of S. mutans and more importantly, they could also inhibit the virulence factors of S. mutans.     

Effects of human milk on adhesion of Streptococcus mutans to saliva-coated hydroxyapatite in vitro

Adhesion of bacteria to pellicle-coated tooth surfaces is the first step in biofilm formation on teeth. The aim of this study was to explore whether human milk prevents or promotes adhesion of cariogenic Streptococcus mutans to saliva-coated hydroxyapatite (HA) using an in vitro model system. S. mutans binding to HA coated with human parotid saliva (s-HA) or human milk was studied, in addition to binding inhibition to s-HA by human milk. S. mutans did not bind to HA coated with milk. S. mutans binding to s-HA was inhibited by milk from 15 (71 %) of 21 women, whereas milk from the remaining 6 mothers enhanced binding of S. mutans to s-HA. Inhibition of S. mutans binding correlated with bacterial binding to s-HA (r = 0.76). Human milk does not mediate adhesion of S. mutans to HA in vitro, but affects adhesion in an individually varying fashion. Phenotypic variations in milk and saliva glycosylation may explain the inhibitory capacity and possibly affect susceptibility to colonization by S. mutans in childhood.