Cell density and cell aging as factors modulating antifungal resistance of Candida albicans biofilms

Biofilm formation is a major virulence attribute of Candida pathogenicity which contributes to higher antifungal resistance. We investigated the roles of cell density and cellular aging on the relative antifungal susceptibility of planktonic, biofilm, and biofilm-derived planktonic modes of Candida. A reference and a wild-type strain of Candida albicans were used to evaluate the MICs of caspofungin (CAS), amphotericin B (AMB), nystatin (NYT), ketoconazole (KTC), and flucytosine (5FC). Standard, NCCLS, and European Committee on Antibiotic Susceptibility Testing methods were used for planktonic MIC determination. Candida biofilms were then developed on polystyrene wells, and MICs were determined with a standard 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide assay. Subsequently, antifungal susceptibility testing was performed for greater inoculum concentrations and 24- and 48-h-old cultures of planktonic Candida. Furthermore, Candida biofilm-derived planktonic cells (BDPC) were also subjected to antifungal susceptibility testing. The MICs for both C. albicans strains in the planktonic mode were low, although on increasing the inoculum concentration (up to 1 × 10⁸ cells/ml), a variable MIC was noted. On the contrary, for Candida biofilms, the MICs of antifungals were 15- to >1,000-fold higher. Interestingly, the MICs for BDPC were lower and were similar to those for planktonic-mode cells, particularly those of CAS and AMB. Our data indicate that higher antifungal resistance of Candida biofilms is an intrinsic feature possibly related to the biofilm architecture rather than cellular density or cellular aging.     

Ultrastructure and morphology of biofilms on thermoplastic orthodontic appliances in 'fast' and 'slow' plaque formers

The aim of this study was to investigate the morphological features and distribution of biofilms on Invisalign orthodontic appliances, in a sample of 'slow' and 'fast' plaque formers using scanning electron microscopy (SEM). Fifty-six Chinese male/female volunteers (aged 19-39 years) were screened for their plaque-forming rate using the plaque percentage index (PPI) coupled with digital photography and computer-based image analysis, after a period of 48 hours of abstinence from oral hygiene procedures. Eleven volunteers (seven males/four females) representing the lowest and highest ends of the plaque formation spectrum were chosen as slow and fast plaque formers, respectively. The subjects wore a full-coverage splint appliance, in which four tiles of Invisalign material were embedded. These tiles were collected at intervals of 1, 3, 6, 12, 24, and 48 hours, as well as 3, 7, and 14 days, immediately fixed in 10 per cent paraformaldehyde in 0.2 M cacodylate buffer solution and prepared for SEM. The surface configuration of the Invisalign appliance was visualized, as well as the chronological pattern of biofilm formation. Significance between fast and slow plaque formers was determined using a Student's t-test. Colonization appeared to centre initially on the raised edges or textured surfaces of the appliance, and initial adhesion was quicker and more abundant in the fast plaque-forming group. In the later stages of biofilm development, both groups showed no discernible differences in biofilm accrual on the surfaces, but the fast group displayed a more complex biofilm structure. More recessed and sheltered areas of the appliance, such as the cusp tips and attachment dimples, harboured more biofilm than the flat surfaces. Hence, it seems that the novel Invisialign orthodontic appliance is a useful tool to investigate the features of biofilm formation in time-course studies.     

Oral submucous fibrosis and oral yeast carriage - a case control study in Sri Lankan patients

Oral submucous fibrosis (OSMF) is a well-known precancerous condition. Epithelial atrophy is one of the key features in OSMF. Presence of Candida in the mouth together with epithelial changes may predispose to candidal infection. Candidal infection together with other co-factors may also induce epithelial atypia and dysplasia leading to malignant change. The purpose of this study was to determine the prevalence of oral yeast carriage in patients with OSMF and to compare the carriage with the normal individuals. Thirty patients with histologically proven OSMF and healthy subjects were used as the test and control respectively. Oral rinse samples were collected from all the subjects and cultured on Sabouraud's agar. Species were identified using API 32C AUX identification kits. Nineteen (63.6%) of the test group and 15 (50%) of the control group had yeast isolated from their mouth. The carriage of yeast in the OSMF group was not statistically significant compared with the control group. We isolated C. dubliniensis in Sri Lanka for the first time and interestingly from the oral cavities of both OSMF patients and healthy individuals.     

膳食补充剂黑醋与红曲单用及联用对中老年人血脂的影响

目的:观察并比较黑醋与红曲单用及联用对中国中老年人降低血脂的效能。方法:试验于2003-10/11在大连医科大学中日合作医药科学研究所进行。选择30名年龄为45￣65岁的中老年人。30名受试者被随机分为3组,每组10人,分别服用黑醋丸6粒,红曲丸6粒或黑醋 红曲丸6粒,1次/d,连续4周;3种膳食补充剂黑醋丸、红曲丸及黑醋 红曲丸由含有不同剂量的黑醋固形物、红曲粉末K-F、柠檬酸钠、大豆油、蜂蜡、脂肪酸甘油脂组成(由日本国第一药品工业株式会社提供)。各组服用剂量分别为每天黑醋固形物360mg,红曲粉72mg及黑醋固形物360mg 红曲粉72mg。服用2和(或)4周后,检测血脂和血糖,同时用血清样品检测肝功与肾功能。实验结果用SPSS统计软件进行方差分析。结果:30名中老年人全部进入结果分析。①受试者连续3d每日营养素摄入量:3组之间热量、胆固醇、膳食纤维、宏量或微量营养素摄入量差距均无显著性。②血清脂质浓度和计算的脂质比:2,4周血清三酰甘油含量,黑醋 红曲组低于基础值(分别下降(24.6±4.9)%,(27.6±3.4)%,P<0.05);红曲组与基础值比较,差异无显著性[分别下降(6.5±3.4)%,(11.6±4.5)%];黑醋组与基础值比较,差异无显著性[分别下降(10.2±7.3)%,(12.4±8.2)%]。2,4周血清胆固醇、低密度脂蛋白胆固醇含量,黑醋 红曲丸、红曲丸和黑醋丸组均比基础值降低,差异无统计学意义。3种膳食补充剂对血清高密度脂蛋白胆固醇及计算的脂质比值无明显改变。血糖含量无变化。未发现对受试对象产生明显不良反应。结论:服用黑醋 红曲丸能明显降低受试者血清三酰甘油含量。黑醋与红曲合用对高脂血症者可能有健康效益。     

Phosphodiesterase 5 inhibitor treatment and survival in interstitial lung disease pulmonary hypertension: A Bayesian retrospective observational cohort study

Background and Objective

Pulmonary hypertension is a life-limiting complication of interstitial lung disease (ILD-PH). We investigated whether treatment with phosphodiesterase 5 inhibitors (PDE5i) in patients with ILD-PH was associated with improved survival.

Methods

Consecutive incident patients with ILD-PH and right heart catheterisation, echocardiography and spirometry data were followed from diagnosis to death, transplantation or censoring with all follow-up and survival data modelled by Bayesian methods.

Results

The diagnoses in 128 patients were idiopathic pulmonary fibrosis (n = 74, 58%), hypersensitivity pneumonitis (n = 17, 13%), non-specific interstitial pneumonia (n = 12, 9%), undifferentiated ILD (n = 8, 6%) and other lung diseases (n = 17, 13%). Final outcomes were death (n = 106, 83%), transplantation (n = 9, 7%) and censoring (n = 13, 10%). Patients treated with PDE5i (n = 50, 39%) had higher mean pulmonary artery pressure (median 38 mm Hg [interquartile range, IQR: 34, 43] vs. 35 mm Hg [IQR: 31, 38], p = 0.07) and percentage predicted forced vital capacity (FVC; median 57% [IQR: 51, 73] vs. 52% [IQR: 45, 66], p=0.08) though differences did not reach significance. Patients treated with PDE5i survived longer than untreated patients (median 2.18 years [95% CI: 1.43, 3.04] vs. 0.94 years [0.69, 1.51], p = 0.003) independent of all other prognostic markers by Bayesian joint-modelling (HR 0.39, 95% CI: 0.23, 0.59, p < 0.001) and propensity-matched analyses (HR 0.38, 95% CI: 0.22, 0.58, p < 0.001). Survival difference with treatment was significantly larger if right ventricular function was normal, rather than abnormal, at presentation (+2.55 years, 95% CI: −0.03, +3.97 vs. +0.98 years, 95% CI: +0.47, +2.00, p = 0.04).

Conclusion

PDE5i treatment in ILD-PH should be investigated by a prospective randomized trial.