16S rDNA PCR detection of Actinobacillus actinomycetemcomitans from periodontitis-free plaque

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Human Serum Promotes Candida albicans Biofilm growth and Virulence Gene Expression on Silicone Biomaterial

Objectives Systemic candidal infections are a common problem in hospitalized patients due to central venous catheters fabricated using silicone biomaterial (SB). We therefore evaluated the effect of human serum on C. albicans biofilm morphology, growth, and the expression of virulence-related genes on SB in vitro. Methods We cultivated C. albicans SC5314 (wild-type strain, WT) and its derivative HLC54 (hyphal mutant, HM) for 48 h in various conditions, including the presence or absence of SB discs, and human serum. The growth of planktonic and biofilm cells of both strains was monitored at three time points by a tetrazolium salt reduction assay and by scanning electron microscopy. We also analyzed by RT-PCR its expression of the virulence-related genes ALS3, HWP1, EAP1, ECE1, SAP1 - SAP10, PLB1, PLB2, PLC and PLD. Results At each time point, planktonic cells of WT strain cultured in yeast nitrogen base displayed a much higher expression of EAP1 and HWP1, and a moderately higher ALS3 expression, than HM cells. In planktonic cells, expression of the ten SAP genes was higher in the WT strain initially, but were highly expressed in the HM strain by 48 h. Biofilm growth of both strains on SB was promoted in the presence of human serum than in its absence. Significant upregulation of ALS3, HWP1, EAP1, ECE1, SAP1, SAP4, SAP6 - SAP10, PLB1, PLB2 and PLC was observed for WT biofilms grown on serum-treated SB discs for at least one time point, compared with biofilms on serum-free SB discs. Conclusions Human serum stimulates C. albicans biofilm growth on SB discs and upregulates the expression of virulence genes, particularly adhesion genes ALS3 and HWP1, and hydrolase-encoding genes SAP, PLB1 and PLB2. This response is likely to promote the colonization of this versatile pathogen within the human host.published_or_final_versio

Pseudomonas aeruginosa inhibits in-vitro Candida biofilm development

<p>Abstract</p> <p>Background</p> <p>Elucidation of the communal behavior of microbes in mixed species biofilms may have a major impact on understanding infectious diseases and for the therapeutics. Although, the structure and the properties of monospecies biofilms and their role in disease have been extensively studied during the last decade, the interactions within mixed biofilms consisting of bacteria and fungi such as <it>Candida spp</it>. have not been illustrated in depth. Hence, the aim of this study was to evaluate the interspecies interactions of <it>Pseudomonas aeruginosa </it>and six different species of <it>Candida </it>comprising <it>C. albicans</it>, <it>C. glabrata, C. krusei</it>, <it>C. tropicalis</it>, <it>C. parapsilosis</it>, and <it>C. dubliniensis </it>in dual species biofilm development.</p> <p>Results</p> <p>A significant reduction in colony forming units (CFU) of <it>C. parapsilosis </it>(90 min), <it>C. albicans </it>and <it>C. tropicalis </it>(90 min, 24 h and 48 h), <it>C. dubliniensis </it>and <it>C. glabrata</it>, (24 h and 48 h) was noted when co-cultured with <it>P. aeruginosa </it>in comparison to their monospecies counterparts (P < 0.05). A simultaneous significant reduction in <it>P. aeruginosa </it>numbers grown with <it>C. albicans </it>(90 min and 48 h), <it>C. krusei </it>(90 min, 24 h and 48 h),<it>C. glabrata</it>, (24 h and 48 h), and an elevation of <it>P. aeruginosa </it>numbers co-cultured with <it>C. tropicalis </it>(48 h) was noted (P < 0.05). When data from all <it>Candida spp</it>. and <it>P. aeruginosa </it>were pooled, highly significant mutual inhibition of biofilm formation was noted (<it>Candida </it>P < 0.001, <it>P. aeruginosa </it>P < 0.01). Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM) analyses confirmed scanty architecture in dual species biofilm in spite of dense colonization in monospecies counterparts.</p> <p>Conclusions</p> <p><it>P. aeruginosa </it>and <it>Candida </it>in a dual species environment mutually suppress biofilm development, both quantitatively and qualitatively. These findings provide a foundation to clarify the molecular basis of bacterial-fungal interactions, and to understand the pathobiology of mixed bacterial-fungal infections.</p

Microbial colonization of spent Minocycline strips - a preliminary report

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Predominant cultivable subgingival flora of renal transplant recipients

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Water concentration in self-etching primers affects their aggressiveness and bonding efficacy to dentin

Water is required to ionize acid resin monomers for demineralization of tooth substrates. We tested the null hypothesis that altering the water concentration in two-step self-etching primers has no effect on their aggressiveness and bonding efficacy to dentin. Five experimental self-etching primers were prepared with resin-water-ethanol volume ratios of 9-0-1, 8-1-1, 7-2-1, 5-4-1, and 3-6-1. They were applied to smear-layer-covered dentin, followed by a bonding resin and composite build-ups for microtensile bond testing and TEM examination of tracer penetration. Increasing water concentration from 0-60 vol% improved acidic monomer ionization that was manifested as increasing hybrid layer thickness. However, significantly higher bond strength was observed in the 7-2-1 group, with minimal nanoleakage in the corresponding hybrid layer. When self-etching primers are formulated, a balance must be achieved to provide sufficient water for adequate ionization of the acidic monomers, without lowering the resin concentration too much, to optimize their bonding efficacy to dentin.published_or_final_versio

Predominant cultivable microflora on spent Minocycline strips

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Genotypic characterization of C. glabrata after exposure to fluconazole

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Microflora cultivable from minocycline strips placed in persisting periodontal pockets

The microflora that develops on minocycline strips, used as an adjunct in non-surgical periodontal therapy was studied. Minocycline (1.4 mg in polycaprolactone vehicle) and control strips were applied into all residual pockets (PD ≥ 5 mm, ≥2 pockets/subject) of patients with chronic periodontitis 1 month after a course of non-surgical periodontal therapy. Strips were inserted and retained for 3 days, changed to new strips for 3 more days and then removed. Strips were recovered from 14 (eight test, six control) of the 34 participants at day 0 (strip inserted, left for 30 s, removed), days 3 and 6, for (i) anaerobic culture, (ii) coliforms culture, using MacConkey agar, (iii) yeast culture, using Sabouraud's dextrose agar. The mean anaerobic cfu/strip (×105; control/test) were 2/6, 24/2, 11/2 at days 0, 3 and 6, respectively (P > 0.05). The corresponding mean proportion of Gram-negative rods and fusiforms were 27%/21%, 27%/15% and 55%/8%. The proportions of Gram-negative rods on test strips by day 6 were significantly reduced (P < 0.05). A significantly increased prevalence of Streptococcus mitis biovar 1 was found on spent test strips (control versus test; 0% versus 38%, Fisher exact test, P = 0.01). Coliform prevalence at days 0, 3 and 6 on control/test strips were 0/13%, 50%/38% and 50%/13%. Yeasts were occasionally isolated. The findings indicated that the minocycline strips but not the control strip supported a microbial colonisation compatible with periodontal health by day 6. © 2004 Elsevier Ltd. All rights reserved.postprin

Biofilm-forming ability of Candida albicans is unlikely to contribute to high oral yeast carriage in human immunodeficiency virus infection

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