Ayurvedic, herbal extracts suppress Candidal biofilms in vitro

Plant derivatives have been used for centuries to treat various human afflictions including microbial infections. A vast majority of these infections are initiated and perpetuated by community dwelling, surface-attached organisms living in micro-econiches known as biofilms. We investigated the biofilm suppressant effect of phytomedicinal preparations used widely in traditional Ayurvedic medicine, Triphala, a mixture of Terminalia bellirica, Terminalia chebula and Emblica officinalis, and Mimusops elengi bark extract. Inhibitory effect of extracts were first investigated against the planktonic C. albicans and C. tropicalis using the well diffusion. Minimum biofilm inhibitory concentration for in-vitro biofilms was determined by MTT assay. The biofilm suppressant effect was determined by measuring biofilm viability at different time intervals, post-exposure to the two herbal extracts, and using MTT. Scanning electron microscopy was performed to assess the post-exposure biofilm architecture. Triphala inhibited both species of the planktonic yeasts, and only the biofilm phase C. tropicalis and mixed species, and not C. albicans. M. elengi had no inhibitory effect on either the planktonic or the biofilms of either Candida species. Ultrastructural microscopy revealed increased cell density of C. albicans biofilm, but not that of C. tropicalis which was significantly reduced in size after Triphala exposure. Triphala, but not M. elengi, extracts exhibit selective and differential biofilm inhibitory activity against Candida. C. albicans biofilms are more resistant to the anti-biofilm activity of Triphala

The genotypes and virulence attributes of C. albicans isolates from oral leukoplakia

There is a debate as to whether some types of oral leucoplakias (OL) are caused by Candida species, and whether they contribute to the malignant transformation, associated with a minority of such lesions. As no detailed population analysis of yeast isolates from OL is available, we evaluated the virulence attributes, and genotypes of 35 C. albicans from OL, and compared their genotypes with 18 oral isolates from healthy individuals. The virulence traits evaluated were esterase, phospholipase, proteinase, haemolysin and coagulase production, and phenotypic switching activity, and yeast adherence and biofilm formation. DNA from OL and control yeasts were evaluated for A, B or C genotype status. Phospholipase, proteinase, and coagulase activity and biofilm formation was observed in 80%, 66%, 97 % and 77 % of the isolates, respectively. Phenotypic switching was detected in 8.6%, while heamolytic, and esterase activity and adherence were noted in all isolates. The genotype A was predominant amongst both the OL and control groups. Due to the small sample size of our study a larger investigation to define the role of candidal virulent attributes in the pathogenicity of OL is warranted, and the current data should serve as a basis until then

Role and dynamics of yeast species in oral biofilms

Oral biofilms are complex microbial ecosystems. In humans there are more than 900 oral microbial species, most with unknown properties or roles in disease. Candida albicans has cariogenic properties but its role in dental caries and in oral biofilms is still unclear. The incidence of oral candidosis and the involvement of non-albicans Candida species, particularly Candida dubliniensis, has recently increased due to HIV infection and immunosuppressive chemotherapy. Oral yeast identification in clinical laboratories mainly relies on culture analysis using CHROMagarTM Candida medium which yields uncertain results when differentiating C. albicans from C. dubliniensis. More reliable molecular methods for the identification of oral yeasts are needed both clinically, and for understanding oral ecosystems. Aims: (1) To develop PCR-DGGE to presumptively identify oral yeast species, in particular to differentiate C. albicans from C. dubliniensis, and to compare its performance with CHROMagar for identification of oral yeasts. (2) To investigate yeast prevalence and diversity in saliva and oral plaque microcosms cultured from different individuals, with and without exposure to three sucrose pulses daily. (3) To identify characteristic populations of bacterial species by DGGE eubacterial fingerprinting of saliva and oral microcosm plaques derived from different individuals, and to determine if any particular population is ecologically associated with the presence and prevalence of Candida species. Methods: PCR-DGGE and CHROMagar were evaluated for the presumptive identification of yeast species in saliva samples (n=25) and microcosm plaques (with confirmation by DNA sequencing). A range of yeast species (11 Candida species, 4 non-Candida species and 20 C. albicans isolates) were used to optimise PCR-DGGE. Previously published primer sets targeting the large subunit rDNA gene (25S–28S) (denoted primer sets N and U, respectively), and small subunit rDNA gene (18S) (primer set E) were used. Microcosm plaque biofilms were cultured from 24 individuals with and without 10% sucrose pulsing (6 minutes every 8 hour) for 11 days in a “Multiplaque Artificial Mouth”. Eubacteria were fingerprinted by PCR-DGGE. Results: Primer set N was highly discriminatory between yeast species and showed 100% specificity in the differentiation of C. dubliniensis from C. albicans. Primer set U often produced multiple bands, and could be used to distinguish six groups of C. albicans strains. Primer set E gave poor discrimination. PCR-DGGE of saliva samples from 25 donors identified yeasts, which were not discriminated by CHROMagar, and were confirmed by sequencing. C. albicans was the predominant yeast (carriage rate 56%) followed by C. dubliniensis (16%). In microcosm plaques, sucrose pulsing selectively promoted the growth of C. albicans and not non-albicans yeast species. No association was found between C. albicans and bacterial DGGE fingerprints of plaque microcosms. Yeasts and bacteria from different people responded differently to sucrose pulsing. Saliva bacterial clusters identified by PCR-DGGE were maintained to a significant degree during plaque microcosm development. Conclusion: PCR-DGGE using primer set N is a specific, sensitive, economical and reproducible technique: to presumptively identify yeast species in the oral cavity; to directly differentiate important multiple yeast species in clinical specimens; and to facilitate oral microbial ecological studies

Proinflammatory Cytokine IL-17 Shows a Significant Association with Helicobacter pylori Infection and Disease Severity

Background. The pro- and anti-inflammatory cytokines play an important role in the immune response against H. pylori infection. The proinflammatory cytokines of Th17 cells have been suggested to play a major role in H. pylori infection and resulting gastric inflammation. Objective. The objective of this study was to compare the expression of selected inflammatory cytokines (IL-10, IL-17, IL-21, IL-23, and TNF-α) in H. pylori-infected patients and healthy controls and to understand their association with H. pylori infection and disease severity. Results. The expression levels of IL-17 and IL-23 were significantly higher in H. pylori-infected patients. The expression of IL-21 was also higher in H. pylori-positive patients but there was no significant association with infection. IL-17 expression showed a significant increase with the severity of chronic gastritis. Conclusion. The proinflammatory cytokine, IL-17, shows a significant association with H. pylori infection and disease severity in a Sri Lankan dyspeptic patient population