The influence of morphological variation on Candida albicans adhesion to denture acrylic in vitro.

Using denture acrylic pieces coated with either whole human stimulated saliva or oral streptococci, the binding ability of three different Candida albicans strains was investigated. The C. albicans strains include a clinical isolate with the commonly observed, smooth, round colonial morphology (strain 613p), a morphological variant spontaneously derived from the clinical isolate strain 613p (strain 613m1BK) and a clinical isolate from an oral lesion that was also a morphological variant upon primary isolation (strain 228). Levels of adhesion to the acrylic pieces were determined radiometrically using C. albicans cells metabolically labelled with [35S]-methionine. Whole stimulated saliva significantly increased the binding of all strains compared to uncoated acrylic. However, the level of binding of strain 613p to saliva-coated acrylic was significantly greater than the levels observed for the morphological variant strain 613m1BK. Coating acrylic pieces with either Streptococcus sanguis NCTC 10904, Strep. mutans GS-5 or Strep. sobrinus ATCC 27352 instead of saliva resulted in significantly greater binding by strain 613p compared to uncoated acrylic. Pre-coating the acrylic with the oral streptococci did not significantly increase the binding of morphological variant strains 613m1BK and 228 compared to uncoated acrylic. In general, preincubation of adherent streptococci with sucrose to induce the synthesis of extracellular carbohydrate polymers did not significantly increase the binding levels of the C. albicans strains above those observed using streptococci in buffer alone. Compared to its parental strain 613p, morphological variant strain 613m1BK adhered poorly to denture acrylic coated with either salivary constituents or oral streptococci, while strain 228 adhered to the same substrates at an intermediate level. Furthermore, physical disaggregation of clusters of the morphological variant strain 613m1BK did not appear to increase its binding capacity to saliva-coated denture acrylic. The effect of whole stimulated saliva on the adherence of C. albicans 613p to a variety of plastic substrates in addition to denture acrylic was examined. Overall, saliva pre-coating of the various plastics promoted C. albicans 613p adhesion. The adhesion of strain 613p to denture acrylic coated with whole stimulated saliva from each of five different donors or with parotid and submandibular/sublingual saliva from each of two donors was also examined. Regardless of donor, a coating of whole stimulated saliva significantly increased the binding of strain 613p to denture acrylic compared to uncoated acrylic. In addition, a coating of parotid saliva significantly increased the binding of strain 613p to denture acrylic compared to submandibular/sublingual saliva.     

The effect of Streptococcus mutans and Candida glabrata on Candida albicans biofilms formed on different surfaces

Although Candida containing biofilms contribute to the development of oral candidosis, the characteristics of multi-species Candida biofilms and how oral bacteria modulate these biofilms is poorly understood. The aim of this study was to investigate interactions between Candida albicans and either Candida glabrata or Streptococcus mutans in biofilms grown on various surfaces, with or without saliva. Hydroxyapatite (HA), polymethylmetacrylate (PMMA) and soft denture liner (SL) discs were used as substratum. Counts of viable micro-organisms in the accumulating biofilm layer were determined and converted to colony forming units per unit surface area. Confocal laser scanning microscopy was used to characterize biofilms and to quantitate the number of hyphae in each condition tested. Viable counts of C. albicans and C. glabrata per mm(2) decreased in the order HA>PMMA>SL (p<0.05). Biofilms grown on saliva-coated specimens harboured fewer C. glabrata than uncoated specimens (p<0.05). Glucose and the presence of S. mutans suppressed C. albicans hyphal formation. Dual Candida species biofilms did not show competitive interaction between the two species. We conclude that Candida biofilms are significantly affected by saliva, substratum type and by the presence of other micro-organisms.     

白假丝酵母菌对变形链球菌产酸能力的影响

目的 初步探讨白假丝酵母菌对变形链球菌产酸能力的影响.方法 实验分A、B、C、D四组,依次为白假丝酵母菌单独培养、变形链球菌单独培养、两菌混合培养、空白对照组.在不同葡萄糖浓度(0.01 ～ 0.15 mol/L)或不同初始pH值(7.0～4.0)下,将两菌单独或混合培养48 h后,测定上清液pH值,采用析因设计资料的方差分析判断两菌的产酸能力间是否存在交互作用,并以变形链球菌单独培养(B组)为参照,评价两菌混合培养(C组)的产酸能力.结果 不同葡萄糖浓度下,白假丝酵母菌均可抑制变形链球菌的产酸力(P＜ 0.001).葡萄糖浓度小于或等于0.10 mol/L时,C组产酸量小于B组(P＜0.05);葡萄糖浓度达到0.15 mol/L时,B、C两组的产酸量差异无统计学意义(P＞0.05).pH为7.0～5.5时,白假丝酵母菌抑制变形链球菌的产酸力(P＜ 0.001);pH≤5时,白假丝酵母菌对变形链球菌的产酸力无影响(P＞0.05).初始pH为7.0时,C组产酸量小于B组(P＜0.05);初始pH降至6.5、6.0时,C组与B组差异无统计学意义(P＞0.05);初始pH降至5.5以下时,C组的产酸量大于B组(P＜0.05).本实验条件下,混合培养的总产酸量随培养基的葡萄糖浓度升高呈增多趋势,随初始pH降低呈减少趋势.结论 白假丝酵母菌对变形链球菌产酸能力的影响及两菌混合培养的产酸力均与培养基葡萄糖浓度和初始pH有关.     

The antimicrobial efficiency of aqueous solutions of calcium hydroxide on Streptococcus mutans, Streptococcus faecalis and Candida albicans, in vitro]

Calcium hydroxide preparations Ca(OH)2 are used as water solutions, putly, liner, cement or artificial material. The therapeutic effect of each medicaments depends on physical and chemical characteristic of additional components. The aim of the paper is to research the sensitivity of Streptococcus faecalis and Candida albicans to different water solution concentrations of calcium hydroxide. As solid plates, Bacto-Mitis-Salivarius agar was used for S. mutans, Torlak blood agar for S. faecalis and Sabourand agar "Torlak" for C. albicans. The holes were drilled in solid plates and were filled by 0.2 ml of water solutions of Ca(OH)2. Preparations, created as described were incubated aerobically at 37 degrees C in the period of 48 hrs. Results were read after 24 as well as after 48 hrs. The examined solutions of Ca(OH)2, revealed the highest antimicrobic effect after 24 hrs. The result remained unchanged even after 48 hrs. The inhibition of S. mutans growth on the solid plate occurred with the concentration of Ca(OH)2 solution from 271.18 x 10(-2) mol/dm3 and pH 12.76. The growth of S. faecalis at the solid plate was inhibited with the concentration of 3335.21 x 10(-3) mol/dm3 and pH 12.82. The inhibition of C. albicans growth on solid plate occurred with the concentration of Ca(OH)2 solution from 1023.20 x 10(-3) mol/dm3 and pH 12.84. The difference in the sensitivity of the examined microorganisms at the same concentrations of Ca(OH)2 solution was observed.     

pH changes of mixed biofilms of Streptococcus mutans and Candida albicans after exposure to sucrose solutions in vitro

ObjectiveThis study aimed to standardize an in vitro experimental model able to reproduce the pH changes that occur in dental biofilm under in vivo conditions, using a mixed biofilm of Streptococcus mutans and Candida albicans.DesignBiofilms were developed for 96 h, and exposed to three different concentrations of sucrose (10, 20 or 30%) during 1, 3 or 5 min. The pH was measured before exposure to sucrose, immediately after its removal from the biofilms, and at 1, 3, 5 and 10 min after removal.ResultsSucrose solutions at 10 and 20% required 1 min to significantly reduce the biofilm pH, while for 30% sucrose a significant reduction was already seen immediately after its removal, even for the shortest exposure time. For an exposure of 3 min to 20% sucrose, the biofilm pH attained the critical value for hydroxyapatite dissolution when measured 1 min after sucrose removal, followed by a recovery phase.ConclusionsA mixed biofilm of S. mutans and C. albicans exposed to a 20% sucrose solution for 3 min exhibited a pattern of pH change similar to that observed in vivo, despite at a higher speed when compared to in vivo conditions.     

Adherence in vitro of various Candida species to acrylic surfaces

Adherence of microorganisms to the surfaces of the host is believed to be an initial and essential step in the production of infection. The objective of the present study was to compare the adherence in vitro of 17 isolates of various Candida species to acrylic surfaces. The results showed that all 17 Candida strains adhered to acryl. Generally, all Candida albicans strains were more adherent than the other strains of Candida species that were tested. Marked differences in the adherence ability of strains belonging to the same species were noted. Future studies to search for possible association between adherence of Candida strains to acryl and pathogenesis of denture stomatitis are planned.     

The effect of two artificial salivas on the adhesion of Candida albicans to heat-polymerized acrylic resin

PURPOSE

Xerostomia can diminish the quality of life, leads to changes in normal chemical composition of saliva and oral microbiata, and increases the risk for opportunistic infections, such as Candida albicans. Various artificial salivas have been considered for patients with xerostomia. However, the knowledge on the antifungal and antiadhesive activity of artificial saliva substitutes is limited. The aim of the present study was to evaluate influence of two artificial salivas on the adhesion of Candida albicans to the polymethylmethacrylate disc specimens.

MATERIALS AND METHODS

Two commercial artificial salivas (Saliva Orthana and Biotene Oral Balance Gel) were selected. 45 polymethylmethacrylate disc specimens were prepared and randomly allocated into 3 groups; Saliva Orthana, Biotene-Oral Balance gel and distilled water. Specimens were stored in the artificial saliva or in the sterile distilled water for 60 minutes at 37℃. Then they were exposed to yeast suspensions including Candida albicans. Yeast cells were counted using ×40 magnification under a light microscope and data were analysed.

RESULTS

Analysis of data indicated statistically significant difference in adhesion of Candida albicans among all experimental groups (P=.000). Findings indicated that Saliva Orthana had higher adhesion scores than the Biotene Oral Balance gel and distilled water (P<.05).

CONCLUSION

In comparison of Saliva Orthana, the use of Biotene Oral Balance Gel including lysozyme, lactoferrin and peroxidase may be an appropriate treatment method to prevent of adhesion of Candida albicans and related infections in patients with xerostomia.     

含精氨酸的抗敏抛光膏对暴露牙本质表面变异链球菌黏附的影响

目的 研究含精氨酸抗敏抛光膏对暴露牙本质表面变异链球菌黏附的影响。方法 暴露牙本质小管,使用浮石粉和抗敏抛光膏处理表面,观察其粗糙度的变化。体外培养变异链球菌,观察其在牙本质片表面黏附及葡糖基转移酶（GTFs）基因表达情况。结果 使用浮石粉及抗敏抛光膏均能有效降低表面粗糙度,抗敏抛光膏处理后的牙本质能明显抑制gtfB和gtfC基因的表达。结论 含精氨酸抗敏抛光膏能抑制变异链球菌黏附及gtfB和gtfC基因的表达,对敏感牙本质区域龋病发生具有一定防治作用。     

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.     

Antigen I/II mediates interactions between Streptococcus mutans and Candida albicans

Streptococcus mutans and Candida albicans are frequently co‐isolated from dental plaque of children with early childhood caries (ECC) and are only rarely found in children without ECC, suggesting that these species interact in a manner that contributes to the pathogenesis of ECC. Previous studies have demonstrated that glucans produced by S. mutans are crucial for promoting the formation of biofilm and cariogenicity with C. albicans; however, it is unclear how non‐glucan S. mutans biofilm factors contribute to increased biofilm formation in the presence of C. albicans. In this study we examined the role of S. mutans antigen I/II in two‐species biofilms with C. albicans, and determined that antigen I/II is important for the incorporation of C. albicans into the two‐species biofilm and is also required for increased acid production. The interaction is independent of the proteins Als1 and Als3, which are known streptococcal receptors of C. albicans. Moreover, antigen I/II is required for the colonization of both S. mutans and C. albicans during co‐infection of Drosophila melanogaster in vivo. Taken together, these results demonstrate that antigen I/II mediates the increase of C. albicans numbers and acid production in the two‐species biofilm, representing new activities associated with this known S. mutans adhesin.     

内源性Farnesol对变异链球菌脱矿作用的研究

[摘要] 目的 观察内源性Farnesol处理变异链球菌后牙釉质脱矿的变化。方法 放置牙釉质切片于培养皿中,实验分5组,前3组加入变异链球菌菌悬液的同时分别添加去离子水、白色念珠菌24h上清、白色念珠菌菌悬液,第四组加入白色念珠菌菌悬液（实验组）,去离子水组为空白对照组。采用原子吸收分光光度法检测不同时间点（24、48、72h）菌悬液中钙离子的浓度。 结果 加入白色念珠菌24 h上清组钙离子的浓度在24、48、72h分别测得（80.26±1.63）、（81.14±1.24）、（78.31±0.76）μg/ml,明显低于其它变异链球菌组,实验组与对照组相比也有显著性差(P<0.05)。变异链球菌作用牙釉质的脱矿过程受到白色念珠菌分泌的Farnesol的调控,其脱矿作用受到明显的抑制。结论 内源性Farnesol可抑制变异链球菌对牙釉质的脱矿作用。     

Current-induced effects on growth and adhesion properties of Streptococcus mutans in vitro

Current-induced effects on the growth and adhesion of Streptococcus mutans were studied. The spontaneous currents formed between gold-amalgam pairs showed starting current peaks of approximately 200 microA followed by constant currents of approximately 15 microA. The presence of the gold-amalgam pair had no effect on the growth of S. mutans, which was unaffected even when constant potentials of 1000 mV and 2000 mV were used to produce extreme experimental conditions. Three volts or more was needed to inhibit the growth of S. mutans. Organic acids produced by S. mutans during growth had also little or no effect on the magnitudes of the spontaneous currents formed between the gold-amalgam pairs. Adhesion of S. mutans, grown with or without added sucrose, appeared unaffected by spontaneous currents induced by the metal combinations.     

Current-induced effects on growth and adhesion properties of Streptococcus mutans in vitro

Abstract – Current-induced effects on the growth and adhesion of Streptococcus mutans were studied. The spontaneous currents formed between gold-amalgam pairs showed starting current peaks of approximately 200 μA followed by constant currents of approximately 15 μA. The presence of the gold-amalgam pair had no effect on the growth of S. mutans , which was unaffected even when constant potentials of 1000 mV and 2000 mV were used to produce extreme experimental conditions. Three volts or more was needed to inhibit the growth of S. mutans . Organic acids produced by S. mutans during growth had also little or no effect on the magnitudes of the spontaneous currents formed between the gold-amalgam pairs. Adhesion of S. mutans , grown with or without added sucrose, appeared unaffected by spontaneous currents induced by the metal combinations.     

The Pst system of Streptococcus mutans is important for phosphate transport and adhesion to abiotic surfaces

The Pst system is a high-affinity inorganic phosphate transporter found in many bacterial species. Streptococcus mutans, the etiological agent of tooth decay, carries a single copy of the pst operon composed of six cistrons (pstS, pstC1, pstC, pstB, smu.1134 and phoU). Here, we show that deletion of pstS, encoding the phosphate-binding protein, reduces phosphate uptake and impairs cell growth, which can be restored upon enrichment of the medium with high concentrations of inorganic phosphate. The relevance of Pst for growth was also demonstrated in the wild-type strain treated with an anti-PstS antibody. Nevertheless, a reduced ability to bind to saliva-coated surfaces was observed, along with the reduction of extracellular polysaccharide production, although no difference on pH acidification was observed between mutant and wild-type strains. Taken together, the present data indicate that the S. mutans Pst system participates in phosphate uptake, cell growth and expression of virulence-associated traits.     

In vitro study on the inhibiting effect of different agents on the growth of Candida albicans on acrylic resin surfaces

This study evaluated at the in vitro level the antifungal effectiveness of nystatin, chlorhexidine, and a homologous histidine polypeptide on the surface of acrylic resin disks. The agents were used in a way that simulated storage of a denture by a denture wearer. Results indicated that pretreatment with poly-L-histidine was not protective against C albicans adherence and growth regardless of whether disks were stored in water or in the open air for the 8-hour period following yeast contamination. Chlorhexidine was totally effective in preventing C albicans attachment to, and growth on, the acrylic resin, even after a period of 8 days of turbidimetric monitoring. Pretreatment with Nystatin, followed by drying, was protective, yielding results similar to those obtained with chlorhexidine.