基于PADTM Plus的光活化消毒技术杀灭白色念珠菌的体外实验研究

目的 研究基于PAD^TM Plus的光活化消毒技术(photo-activated disinfection,PAD)体外杀灭白色念珠菌的效果。方法 选取白色念珠菌标准株SC5314配制菌悬液。光活化消毒仪输出功率为750 mW，光敏剂为甲苯胺蓝(Toluidine Blue O, TBO)溶液，有效浓度0.75 mg/mL，光源为波长635 nm的LED红光。实验分为空白对照组(P-L-)、单纯光敏剂孵育60 s组(P+T1+L-)、单纯光敏剂孵育120 s组(P+T2+L-)、单纯光照组(P-L+)、PAD孵育60 s组(P+T1+L+)、PAD孵育120 s组(P+T2+L+)，光照时间均为60s。根据不同分组的处理方法对白色念珠菌悬液进行处理后接种于ChROMagar培养基，并于37℃环境下培养48 h，菌落计数以每毫升菌落形成单位(CFU/mL)表示。采用统计学方法分析结果。结果 P-L-组、P+T1+L-组、P+T2+L-组与P-L+组的对比其菌落对数的差异均无统计学意义(P>0.05)，而P+T1+L+组和P+T2+L+组与P-L-组的对比差异...     

光活化消毒治疗小鼠急性假膜型念珠菌性口炎的效果观察

目的:采用光活化消毒技术(Photo-activated disinfection, PAD)治疗小鼠急性假膜型念珠菌性口炎,观察治疗前后舌背病损变化及组织病理学变化,探讨PAD治疗急性假膜型念珠菌性口炎模型的效果,比较不同孵育时间对疗效的影响,为PAD治疗急性假膜型念珠菌性口炎提供实验依据。方法:选取6周龄雄性ICR小鼠,建立急性假膜型念珠菌性口炎模型36只并随机分为对照组、PAD治疗1组(以下称治疗1组)和PAD治疗2组(以下称治疗2组),每组12只。治疗前测量所有小鼠舌背病损面积。两治疗组小鼠舌背部涂抹1 mg/mL的甲苯胺蓝溶液,治疗1组孵育1 min,治疗2组孵育2 min,两组均给予750 mW LED红光照射1min。对照组小鼠不接受任何治疗。治疗后48 h,分别观察3组小鼠的临床表现,测量舌背病损面积,行组织病理学检查,评估PAD治疗小鼠急性假膜型念珠菌性口炎的效果。结果:PAD治疗前,3组舌背白色假膜病损评分差异无统计学意义(P>0.05)。治疗后48 h,两治疗组舌背假膜病损评分均低于对照组,具有统计学意义(P<0.05),两治疗组间舌背假膜病损评分差异...     

In vitro activity of photoactivated disinfection using a diode laser in infected root canals

Objective. To investigate the lethal activity of photoactivated disinfection (PAD) on Enterococcus faecalis (ATCC 29212) and mixed populations of aerobic or anaerobic bacteria in infected root canals using a diode laser after the application of a photosensitizer (PS). Materials and methods. First, the bactericidal activity of a low power diode laser (200 mW) against E. faecalis ATCC 29212 pre-treated with a PS (toluidine blue) for 2 min were examined after different irradiation times (30 s, 60 s and 90 s). The bactericidal activity in the presence of human serum or human serum albumin (HSA) was also examined. Second, root canals were infected with E. faecalis or with mixed aerobic or anaerobic microbial populations for 3 days and then irrigated with 1.5% sodium hypochlorite and exposed to PAD for 60 s. Results. Photosensitization followed by laser irradiation for 60 s was sufficient to kill E. faecalis. Bacteria suspended in human serum (25% v/v) were totally eradicated after 30 s of irradiation. The addition of HSA (25 mg/ml or 50 mg/ml) to bacterial suspensions increased the antimicrobial efficacy of PAD after an irradiation time of 30 s, but no longer. The bactericidal effect of sodium hypochlorite was only enhanced by PAD during the early stages of treatment. PAD did not enhance the activity of sodium hypochlorite against a mixture of anaerobic bacteria. Conclusions. The bactericidal activity of PAD appears to be enhanced by serum proteins in vitro, but is limited to bacteria present within the root canal.     

HIV感染者及艾滋病患者口腔白色念珠菌毒性的体外研究

目的从白色念珠菌本身毒性变化的角度探讨人类免疫缺陷病毒(HIV)感染者易感染口腔念珠菌病的原因。方法通过体外试验从天冬氨酸蛋白酶活性、对颊黏膜上皮细胞的黏附性两方面比较HIV阳性与阴性宿主口腔内白色念珠菌的致病能力。结果在天冬氨酸蛋白酶活性和黏附性方面,HIV阳性口腔念珠菌病致病菌的毒性显著低于HIV阴性口腔念珠菌病致病菌(P<0.01);寄生菌间差异无统计学意义;HIV阳性宿主中,口腔念珠菌病致病菌与寄生菌间差异无统计学意义;而HIV阴性宿主中,口腔念珠菌病致病菌毒性显著高于寄生菌(P<0.01)。结论HIV感染者口腔念珠菌病与某些占主导优势的高毒性菌株无关,而HIV阴性的普通宿主则可能与其选择毒性更强的菌株有关。     

Biofilm formation of Candida albicans on implant overdenture materials and its removal

Objectives

The purposes of this study were to clarify the surface characteristics of various implant overdenture materials and the capabilities of Candida albicans adherence and biofilm formation on these surfaces, and to investigate the role of salivary mucin in biofilm formation.

Methods

Seven commonly used implant and restorative materials were assessed. The surface roughness averages of all materials were limited to 0.07–0.10 μm. Contact angles and salivary mucin absorption were measured. After 90-min initial adhesion and 2-day biofilm formation, the amounts of C. albicans were determined by counting colony-forming units and the morphological characteristics were observed by scanning electron microscopy (SEM). The effects of saliva coating and the influences of material surface property on initial adhesion, biofilm formation and its removability were analysed by univariate two-way analysis of variance and multiple linear regression analysis.

Results

Surface contact angle of materials, the index of hydrophobicity, was found to be correlated positively with initial adhesion and biofilm formation of C. albicans. A negative correlation between mucin absorption and removability of Candida biofilm indicates that mucin plays an important role in biofilm formation and its rigidity. SEM observation also revealed fewer Candida cells on saliva-coated Ti than on saliva-coated hydroxyapatite or acrylic resin.

Conclusions

The materials with different hydrophobic property and compositions display diverse manners of salivary mucin absorption, initial adhesion and biofilm formation. The hydrophobic materials encourage enhanced initial adhesion, subsequently resulting in the active biofilm formation. Mucin has decisive effects on Candida immobilization and biofilm development on the materials.

Clinical significance

Surface hydrophilic property and composition of materials and salivary proteins, especially mucin, affect the process of Candida biofilm formation and influence the amount and rigidity of formed biofilm. The present data may be applied as a reference for selecting materials in implant overdenture treatment from a microbiological point of view.     

白念珠菌生物被膜耐药株麦角甾醇检测的方法学研究

目的：分别采用高效液相色谱法和气相色谱质谱联用法测定白念珠菌麦角甾醇含量,并对这两种方法进行比较。方法：采用浓度梯度递增法诱导白念珠菌耐药株,采用KONT真菌显色MIC药敏系统鉴定耐药性。构建6、12、24h生物被膜,采用高效液相色谱法和气相色谱质谱联用法测定麦角甾醇含量。结果：高效液相色谱法检测出麦角甾醇含量,最低检出浓度为0.05mg/L,而气相色谱质谱联用法未检测出麦角甾醇含量。结论：高效液相色谱法能准确测定白念珠菌麦角甾醇含量。与气相色谱质谱联用法比较,高效液相色谱法简单、高效和可靠。     

Oral Candida albicans from patients infected with the human immunodeficiency virus and characterization of a genetically distinct subgroup of Candida albicans

Candida albicans has been shown to vary in its phenotypic expression with the progression of human immunodeficiency virus (HIV) infection. This study was designed to investigate whether in Category IV HIV infected patients (CDC, Atlanta, USA) these phenotypic changes were related to changes in the genetic strain of the organism. Isolates of C. albicans were obtained from 45 patients with HIV infection during the progression of their disease as determined by percentage T4 lymphocyte count. Isolates were strain differentiated using two methods. In 67 per cent of the patients a single strain of C. albicans, as determined by the DNA analysis, was isolated from each individual over the experimental period. The phenotypic expression of the genetically identical strains isolated from each patient varied considerably over the experimental period with the morphotype 754 being predominant. These results showed that the genotype of C. albicans isolated persisted in the majority of HIV infected individuals, but that the phenotypical expression of this strain changed. A finding in this study was that 18 strains of C. albicans had DNA which did not hybridize to the probe used. These strains were analysed for the presence of two other C. albicans specific DNA segments using PCR. The probe 27A hybridizing strains yielded PCR products which differed from the non-hybridizing strains. Five of these genetically atypical C. albicans strains and 98 of the C. albicans strains were then analysed for purported virulence factors. The genetically atypical C. albicans strains, by comparison with typical C. albicans strains, produced greater amounts of extracellular proteinase (p = 0.038, Student's t test), adhered to a greater degree to buccal epithelial cells (p = 0.018, Student's nest) and were less susceptible to the anti-fungal drug flucytosine (p = 0.0003, Mann-Whitney test). Analysis of these strains with other common antifungal drugs showed no statistically significant variation in susceptibility. The results of this study indicated that these genetically atypical C. albicans strains possess increased virulence by comparison with typical C. albicans strains.