Diabetes mellitus as a contributory factor in oral candidosis.

It has been reported that poor glycaemic control predisposes to oral candidal infection in diabetic patients. For instance, the carriage of Candida species and the density of candidal growth in the oral cavity is frequently claimed to be increased in patients with diabetes mellitus. However, the validity of these observations remains controversial. Hence, we review and discuss here the clinical data in the literature on the relationship between diabetes and oral candidal carriage and infection, and possible mechanisms associated with its pathogenicity.     

Genetic polymorphisms of orosomucoid and alpha-2-HS-glycoprotein in Thai,Sri Lankan and Paraguayan populations

The genetic polymorphism of orosomucoid (ORM) and alpha-2-HS-glycoprotein (AHSG) were studied in Thai, Sri Lankan and Paraguayan populations using isoelectric focusing. Gene frequencies in these populations were compared with those in other populations. Four new ORM variants were detected:ORM1 ^* 15 in Thai,ORM1 ^* 16 in Paraguayan,ORM2 ^* 21 andORM2 ^* 22 in Sri Lankan.     

Persistent inhibition of Candida albicans biofilm and hyphae growth on titanium by graphene nanocoating

ObjectivesCandida albicanscolonizes biomaterial surfaces and are highly resistant to therapeutics. Graphene nanocoating on titanium compromises initial biofilm formation. However, its sustained antibiofilm potential is unknown. The objective of this study was to investigate the potential of graphene nanocoating to decrease long-term fungal biofilm development and hyphae growth on titanium.MethodsGraphene nanocoating was deposited twice (TiGD) or five times (TiGV) on grade 4 titanium with vacuum assisted technique and characterized with Raman spectroscopy and atomic force microscope. The biofilm formation and hyphae growth of C. albicans was monitored for seven days by CFU, XTT, confocal, mean cell density and scanning electronic microscopy (SEM). Uncoated titanium was the Control. All tests had three independent biological samples and were performed in independent triplicates. Data was analyzed with one- or two-way ANOVA and Tukey's HSD (α = 0.05).ResultsBoth TiGD and TiGV presented less biofilms at all times points compared with Control. The confocal and SEM images revealed few adhered cells on graphene coated samples, absence of hyphae and no features of a mature biofilm architecture. The increase in number of layers of graphene nanocoating did not improve its antibiofilm potential.SignificanceThe graphene nanocoating exerted a long-term persistent inhibitory effect on the biofilm formation on titanium. The fewer cells that were able to attach on graphene coated titanium were scattered and unable to form a mature biofilm with hyphae elements. The findings open opportunities to prevent microbial attachment and proliferation on implantable materials without the use of antibiotics.     

Effects of Two Different Growth Media on the Postantifungal Effect Induced by Polyenes on Candida Species

There are no data on the effects of different growth media on polyene-induced postantifungal effect (PAFE) in Candida species. Hence, the nystatin- and amphotericin B-induced PAFEs in six Candida species (26 isolates) grown in Sabouraud's dextrose broth (SAB) and RPMI broth were evaluated, following limited exposure to the MICs of the two polyenes, using an automated turbidometric method. For nystatin, PAFE varied between 1.88 and 4.87 h in SAB and 0.66 and 6.89 h in RPMI, and for amphotericin B, the equivalent values were 3.13 to 10.98 h in SAB and 0.97 to 7.01 h in RPMI. These highly significant (P < 0.001) variations in the PAFE with both drugs, noted with most Candida strains grown in different media, call for standardization of intralaboratory methodology in measuring this parameter in order to obtain universally comparable data.     

Antimycotic agents in oral candidosis: an overview: 1. Clinical variants

The advent of the human immunodeficiency virus and the increasing prevalence of immunocompromised individuals in the community have resulted in a resurgence of opportunistic infections, including oral candidoses. Despite the availability of a number of effective antimycotics for the management of oral candidoses, therapeutic failure is not uncommon. Further, the presence of many clinical variants of oral candidosis, both new and old, may confound the unwary clinician and complicate its management. These problems have been partly circumvented by the introduction of the triazole group of antimycotics, which initially appeared to be highly effective. However, an alarming increase in organisms resistant to triazoles has been reported recently. In this paper we provide an overview of clinical variants of oral candidosis. A second paper will discuss recent advances in the usage of antimycotics in the management of this condition.     

The impact of chlorhexidine gluconate on the relative cell surface hydrophobicity of oral Candida albicans

OBJECTIVES: Adherence of Candida albicans has been implicated as the first step in the pathogenesis of oral candidosis, and its relative cell surface hydrophobicity (CSH) a contributory physical force. Chlorhexidine gluconate is by far the commonest antiseptic mouthwash prescribed in dentistry. The intra-oral concentrations of the retained chlorhexidine mouthwash fluctuate considerably due to the dilution effect of saliva and the cleansing action of the oral musculature. Hence the objective of the present study was to investigate the effect of brief exposure to sub-therapeutic concentrations of chlorhexidine gluconate on the relative CSH of C. albicans. DESIGN: The CSH of the isolates was assessed by a biphasic aqueous-hydrocarbon assay. RESULTS: A statistically significant reduction in CSH was observed following the exposure of Candida isolates to 0.005 and 0.0025% chlorhexidine gluconate. CONCLUSIONS: These results elucidate additional mechanisms by which chlorhexidine gluconate suppress candidal pathogenicity despite a brief period of transient exposure within the oral environment.     

Adhesion of Candida parapsilosis to epithelial and acrylic surfaces correlates with cell surface hydrophobicity

We investigated in vitro adherence of 24 isolates of Candida parapsilosis and 12 isolates of Candida albicans with regard to their relative cell-surface hydrophobicity (CSH), adherence to human buccal epithelial cells (BEC) and acrylic surfaces. There was no significant interspecies difference in the relative adherence of C. parapsilosis and C. albicans isolates to BEC, although the former demonstrated a tendency for increased adherence. However, a significant intra-species variation in adherence among isolates of C. parapsilosis (P < 0.0001) to BEC, but not of C. albicans was noted. The superficial isolates of C. parapsilosis demonstrated a higher avidity (33%) to BEC than the systemic isolates. On regression analysis a significant positive correlation between C. parapsilosis adherence to BEC and denture acrylic surfaces was noted (r = 0.45, P = 0.02). Similarly, buccal cell adherence correlated strongly with CSH of C. parapsilosis (r = 0.63, P = 0.0008). These results shed further light on the intimate relationship between adherence and CSH in candidal colonization and imply that both C. parapsilosis and C. albicans are equally potent in colonizing mucosal surfaces with respect to the attributes investigated.     

The effect of brief exposure to sub‐therapeutic concentrations of chlorhexidine gluconate on germ tube formation of oral Candida dubliniensis

Adherence of Candida has been implicated as the first step in the pathogenesis of oral candidosis, and germ tube formation, a contributory attribute. While chlorhexidine gluconate is by far the most common antiseptic mouthwash prescribed in dentistry, its intraoral concentration fluctuates considerably because of the dynamics of the oral cavity. Hence, the main objective of this study was to investigate the effect of brief exposure to three different sub‐therapeutic concentrations of chlorhexidine gluconate on germ tube formation of Candida dubliniensis. Twelve oral isolates of C. dubliniensis were exposed to three different sub‐therapeutic concentrations of 0.005%, 0.0025% and 0.00125% chlorhexidine gluconate for 30 min. The antiseptic was removed, and following subsequent incubation in a germ tube inducing medium, the germ tube formation of these isolates was quantified microscopically. When compared with the controls, brief exposure to 0.005%, 0.0025% and 0.00125% chlorhexidine gluconate suppressed the ability to form germ tubes by 76.53% (P < 0.01), 49.17% (P < 0.01) and 3.45% (P > 0.05) respectively. These findings imply that brief exposure to sub‐therapeutic levels of chlorhexidine gluconate may modulate germ tube formation of C. dubliniensis, thereby suppressing its pathogenicity in vivo.     

The effect of limited exposure to antifungal agents on the germ tube formation of oral Candida albicans

Candidal adherence has been implicated as the first step in the pathogenesis of oral candidosis, and germ tube formation by Candida albicans has been attributed as a co-factor that promotes adherence. Oral candidosis is treated with polyenes and the azole group of antifungal agents. As the intraoral concentrations of antifungals fluctuate considerably due to the dynamics of the oral cavity, we investigated the effect of short exposure to sub-lethal concentrations of antifungals on the germ tube formation of Candida albicans. After determining the minimum inhibitory concentration (MIC) of the antifungal agents, ten oral isolates of Candida albicans were exposed to sub-lethal concentrations of nystatin (6xMIC), amphotericin B (8xMIC), 5-fluorocytosine (8xMIC), ketoconazole (4xMIC) and fluconazole (4xMIC), for 1 h. Following removal of the antifungal agent and subsequent incubation in a germ tube-inducing medium, the germ tube formation of these isolates was quantified. When compared with the controls, exposure to nystatin and amphotericin B almost completely inhibited germ tube formation of all the isolates (mean percentage reduction of 97.68 and 97.52%, respectively; P <0.0001), while ketoconazole suppressed this activity to a lesser degree (30.84%; P =0.0174). However, 5-fluorocytosine- and fluconazole-mediated germ tube suppression was minimal (12.63 and 15.93%, respectively; P =0.3255 and P =0.3791). In clinical terms, these findings indicate that short exposure to sub-therapeutic levels of commonly prescribed antifungals may modulate candidal germ tube formation, and thereby the clearance of the organisms from the oral cavity.     

Hydrophobicity of graphene as a driving force for inhibiting biofilm formation of pathogenic bacteria and fungi

Objective

To evaluate the surface and wettability characteristics and the microbial biofilm interaction of graphene coating on titanium.