Oral candidal carriage and infection in insulin-treated diabetic patients

A mouse model of immunosuppression facilitates oral Candida albicans biofilms, bacterial dysbiosis and dissemination of infection

Opportunistic pathogens are a major threat to people, especially those with impaired immune systems. Two of the most important microbes in this category are the fungus Candida albicans and Gram-positive bacteria of the genus Enterococcus, which share overlapping niches in the oral cavity, gastrointestinal and urogenital tracts. The clinical importance of oral C. albicans biofilm and its interaction with the host under immunosuppressive conditions remains largely understudied. Here, we used a mouse model of oropharyngeal candidiasis (OPC) with cortisone acetate injection on alternate days and a continuous supply of C. albicans in drinking water for three days, resulting in immunosuppression. Results showed abundant growth of resident oral bacteria and a strong C. albicans biofilm on the tongue consisting of hyphae which damaged papillae, the epidermal layer, and invaded tongue tissue with the accumulation of inflammatory cells as demonstrated by Grocott's methenamine silver and hematoxylin and eosin staining, respectively. The dispersed microbes from the oral biofilm colonized the gastrointestinal (GI) tract and damaged its integrity, disseminating microbes to other organs. Although no visible damage was observed in the kidney and liver, except increased lipid vacuoles in the liver cells, C. albicans was found in the liver homogenate. Intriguingly, we found co-occurrence of Enterococcus faecalis in the tongue, liver, and stool of immunosuppressed control and C. albicans infected organs. Targeted 16S rRNA and ITS2 amplicon sequencing of microbes from the fecal samples of mice confirmed the above results in the stool samples and revealed an inverse correlation of beneficial microbes in the dysbiosis condition. Our study shows that mucosal-oral infection of C. albicans under immunosuppressed conditions causes tissue damage and invasion in local and distant organs; the invasion may be aided by the overgrowth of the resident endogenous Enterobacteriaceae and other members, including the opportunistic pathogen Enterococcus faecalis.

Pathophysiological microenvironments in oral candidiasis

Oral candidiasis (OC), a prevalent opportunistic infection of the oral mucosa, presents a considerable health challenge, particularly in individuals with compromised immune responses, advanced age, and local predisposing conditions. A considerable part of the population carries Candida in the oral cavity, but only few develop OC. Therefore, the pathogenesis of OC may depend on factors other than the attributes of the fungus, such as host factors and other predisposing factors. Mucosal trauma and inflammation compromise epithelial integrity, fostering a conducive environment for fungal invasion. Molecular insights into the immunocompromised state reveal dysregulation in innate and adaptive immunity, creating a permissive environment for Candida proliferation. Detailed examination of Candida species (spp.) and their virulence factors uncovers a nuanced understanding beyond traditional C. albicans focus, which embrace diverse Candida spp. and their strategies, influencing adhesion, invasion, immune evasion, and biofilm formation. Understanding the pathophysiological microenvironments in OC is crucial for the development of targeted therapeutic interventions. This review aims to unravel the diverse pathophysiological microenvironments influencing OC development focusing on microbial, host, and predisposing factors, and considers Candida resistance to antifungal therapy. The comprehensive approach offers a refined perspective on OC, seeking briefly to identify potential therapeutic targets for future effective management.

Anti-virulence strategy of diaryl chalcogenide compounds against Candida albicans infection

Candida albicans is an important opportunistic pathogenic fungus that frequently causes serious systemic infection in humans. Due to the vital roles of biofilm formation and the yeast-to-hypha transition in the infection process, we have selected a series of diaryl chalcogenides and tested their efficacy against C. albicans SC5314 pathogenicity by the inhibition of biofilm formation and the yeast-to-hypha transition. The compounds 5-sulfenylindole and 5-selenylindole were found to have excellent abilities to inhibit both biofilm formation and hyphal formation in C. albicans SC5314. Intriguingly, the two leading compounds also markedly attenuated C. albicans SC5314 virulence in human cell lines and mouse infection models at micromolar levels. Furthermore, our results showed that the presence of the compounds at 100 µM resulted in a marked decrease in the expression of genes involved in the cAMP-PKA and MAPK pathways in C. albicans SC5314. Intriguingly, the compounds 5-sulfenylindole and 5-selenylindole not only attenuated the cytotoxicity of Candida species strains but also showed excellent synergistic effects with antifungal agents against the clinical drug-resistant C. albicans strain HCH12. The compound 5-sulfenylindole showed an obvious advantage over fluconazole as it could also restore the composition and richness of the intestinal microbiota in mice infected by C. albicans. Together, these results suggest that diaryl chalcogenides can potentially be designed as novel clinical therapeutic agents against C. albicans infection. The diaryl chalcogenides of 5-sulfenylindole and 5-selenylindole discovered in this study can provide new direction for developing antifungal agents against C. albicans infection.

Oral Candidiasis of Tobacco Smokers: A Literature Review

The mouth is a vital point of entry into the human body, the health of the mouth entails mental, physical as well as social well-being. Studying diseases, microbiota and environmental conditions of the mouth is important to maintain oral health and all body. The smoke of tobacco cigarettes is one of the worst habits that affect the health of the mouth and the body. Therefore, this review has been conducted to study the effect of smoking on the balance of the oral microbiota and the opportunistic organisms, one of the most important of them <i>Candida</i>. Although a few studies have found that cigarette smoking does not influence carriage by <i>Candida</i> significantly. However, most of the studies had results completely contrary to that, smoking cigarettes affect <i>Candida</i> pathogenic characteristics such as a transition from yeast to hyphal form, biofilm formation and, virulence-related gene expressions. Tobacco is not only an inducer of the transition process but it considers an excellent medium for this process. Furthermore, smoking was significantly associated with <i>Candida</i> pathogenicity in patients with clinically suspected oral leukoplakia and smoking worsens oral candidiasis and dampens epithelial cell defense response. Nicotine significantly altered the composition and proportion of yeast cells, as well as the extracellular polysaccharide amounts which increase biofilm matrix and thickness which could promote oral candidiasis. Smoking has the potential to alter the oral condition and cause severe oxidative stress, thereby damaging the epithelial barrier of the mouth. These oxidative molecules during smoking activate epithelial cells proteins called oxidative stress-sensing proteins. If some of these proteins induced, widely thought to have anti-inflammatory properties, inhibit the secretion of pro-inflammatory cytokines and are linked to inflammation and oxidative stress is thought to be a possible therapeutic objective and a crucial regulator for smoking-related oral diseases and mouth candidiasis for instance leukoplakia. Also, it is transported into the cell nucleus in the existence of additional electrophilic chemicals to activate antioxidant enzyme gene expression. Therefore, smoking cigarettes destroys oral health and consequently destroys the health of the whole body.

Coexpression network analysis of human candida infection reveals key modules and hub genes responsible for host-pathogen interactions

Invasive fungal infections are a significant reason for morbidity and mortality among organ transplant recipients. Therefore, it is critical to investigate the host and candida niches to understand the epidemiology of fungal infections in transplantation. Candida albicans is an opportunistic fungal pathogen that causes fatal invasive mucosal infections, particularly in solid organ transplant patients. Therefore, identifying and characterizing these genes would play a vital role in understanding the complex regulation of host-pathogen interactions. Using 32 RNA-sequencing samples of human cells infected with C. albicans, we developed WGCNA coexpression networks and performed DESeq2 differential gene expression analysis to identify the genes that positively correlate with human candida infection. Using hierarchical clustering, we identified 5 distinct modules. We studied the inter- and intramodular gene network properties in the context of sample status traits and identified the highly enriched genes in the correlated modules. We identified 52 genes that were common in the most significant WGCNA turquoise module and differentially expressed genes in human endothelial cells (HUVEC) infection vs. control samples. As a validation step, we identified the differentially expressed genes from the independent Candida-infected human oral keratinocytes (OKF6) samples and validated 30 of the 52 common genes. We then performed the functional enrichment analysis using KEGG and GO. Finally, we performed protein-protein interaction (PPI) analysis using STRING and CytoHubba from 30 validated genes. We identified 8 hub genes (JUN, ATF3, VEGFA, SLC2A1, HK2, PTGS2, PFKFB3, and KLF6) that were enriched in response to hypoxia, angiogenesis, vasculogenesis, hypoxia-induced signaling, cancer, diabetes, and transplant-related disease pathways. The discovery of genes and functional pathways related to the immune system and gene coexpression and differential gene expression analyses may serve as novel diagnostic markers and potential therapeutic targets.

Clinico-Cytological Study of Fungal Elements in the Buccal Smears of Prediabetic, Diabetic, and Nondiabetic Individuals in Association with Burning Sensation

Introduction:

Diabetes mellitus is a metabolic disorder that may have profound effects on oral mucosa being prone to infections, particularly candidiasis. In healthy individuals, the candida is a commensal, but in diabetic patients, it forms severe colonization, even in the absence of any clinically evident lesion and may cause a burning sensation of the mouth. This study aims to identify the presence or absence of fungal elements in buccal smears of nondiabetic, prediabetic, and diabetic individuals and to correlate the presence or absence of burning sensation in the oral cavity.

Materials and Methods:

A total of ninety individuals were selected for the study and divided into Group 1 – thirty cases of diabetics, Group 2 – thirty cases of prediabetic patients, and Group 3 – thirty cases of nondiabetic individuals. Detailed case history and thorough intra and extraoral examination were recorded. The buccal smears were cultured in Sabouraud dextrose agar, subcultured in HiCrome™ agar, observed for the colonies of fungal elements, and were analyzed for species differentiation.

Results:

There was a positive correlation between the presence of fungal elements and burning sensation in diabetic individuals, whereas it was not the case in the nondiabetic and prediabetic individuals.

Conclusion:

Candida colonization is one among a factor in diabetic individuals related with burning sensation of the mouth.

Prevalence of species-specific candidiasis and status of oral hygiene and dentition among diabetic patients: A hospital-based study

Objective

The study was undertaken to estimate the species-specific prevalence of oral candidiasis in diabetic individuals in India, and further find the relationship of oral carriage of Candida in diabetes with degree of diabetic control, duration of disease, type of diabetes and its effect on the status of oral hygiene status and decayed, missing and filled teeth (DMFT) score.

Methodology

The prospective cross-sectional study involved 900 individuals (470 diabetic and 430 non-diabetic) visiting a tertiary care hospital. Informed consent was obtained from all the individuals participating in the study. The demographic details, medical history and oral cavity examination were recorded in a specially designed proforma. Swabs were taken for microbiological evaluation for specific prevalence of Candida.

Results

The overall prevalence of Candida in diabetics was 22.1% as compared to 9.7% in non-diabetic individuals. However, among the type 1 and type 2 diabetics, the prevalence of Candida was equally distributed as 22.6% and 20.8%, respectively. C. albicans was the most common species (97.1%), while isolated cases of other species like C. rugosa, C. tropicalis, C. glabrata were also observed. The individuals with higher glycaemic score (HbA1c >7) showed higher prevalence of oral candidiasis. Oral hygiene status was observed to be lower among diabetics as compared to non-diabetic individuals.

Conclusion

Oral candidiasis was more prevalent in diabetic patients, and C. albicans was the most common species. The diabetics also showed higher mean DMFT with lower oral hygiene status as compared to non-diabetic individuals.

Antifungal activity of hypocrellin compounds and their synergistic effects with antimicrobial agents against Candida albicans

Candida albicans is a common human fungal pathogen. The previous study revealed that quinone compounds showed antimicrobial activity against C. albicans by inhibiting cell growth. However, it was unclear whether quinones have other antifungal effects against C. albicans in addition to fungicidal effects. In this study, we assessed the inhibitory activity of a total of 25 quinone compounds against C. albicans morphological transition, which is essential for the pathogenicity of C. albicans. Several quinones exhibited strong inhibition of mycelium formation by C. albicans SC5314. Three leading compounds, namely hypocrellins A, B and C, also exhibited marked attenuation of C. albicans SC5314 virulence in both human cell lines and mouse infection models. These three compounds significantly suppressed the proliferation of C. albicans SC5314 cells in a mouse mucosal infection model. Intriguingly, hypocrellins not only attenuated the cytotoxicity of a nystatin-resistant C. albicans strain but also showed excellent synergistic effects with antifungal agents against both wild-type C. albicans SC5314 and the drug-resistant mutant strains. In addition, hypocrellins A, B and C interfered with the biological functions and virulence of various clinical Candida species, suggesting the promising potential of these compounds for development as new therapeutic agents against infections caused by Candida pathogens.

Dimethylaminododecyl methacrylate inhibits Candida albicans and oropharyngeal candidiasis in a pH-dependent manner

The prevalence of stomatitis, especially that caused by Candida albicans, has highlighted the need for new antifungal agents. We previously found that a type of quaternary ammonium salts, dimethylaminododecyl methacrylate (DMADDM), incorporated in dental materials inhibited the growth and hyphal development of C. albicans. However, how the quaternary ammonium salts inhibited the fungal pathogens and whether the oral condition, such as salivary pH variation under different diseases, can affect the antimicrobial capacity of quaternary ammonium salts is unknown. This study evaluated the antifungal effects of DMADDM at different pH in vitro and in vivo. A pH-dependent antifungal effect of DMADDM was observed in planktonic and biofilm growth. DMADDM enhanced antifungal activity at alkaline pH. Two pH-regulated genes (PHR1/PHR2) of C. albicans were correlated with the pH-dependent antifungal effects of DMADDM. The PHR1/PHR2 genes and pH values regulated the zeta potential of C. albicans, which then influenced the binding between C. albicans cells and DMADDM. The pH-dependent antifungal activity of DMADDM was then substantiated in a murine oropharyngeal candidiasis model. We directly demonstrated that the antifungal abilities of quaternary ammonium salts relied on the cell zeta potential which affected the binding between fungal cells and quaternary ammonium salts. These findings suggest a new antifungal mechanism of quaternary ammonium under different pH and that DMADDM can be a potential antifungal agent applied in dental materials and stomatitis therapy.Key Points • DMADDM has stronger antifungal activity in alkaline than in acidic pH conditions. • The pH values and pH-regulated genes can affect the zeta potential of fungal cells. • Zeta potential of fungal cells directly affect the binding between DMADDM and cells. Graphical abstract Schematic diagram of the antifungal activities of DMADDM at different pH values.

Clinical and microbial oral health status in children and adolescents with type 1 diabetes mellitus

OBJECTIVES

To study the oral health of young individuals with controlled and uncontrolled type 1 diabetes mellitus (T1DM) and compare the results with those for healthy counterparts.

MATERIALS AND METHODS

One-hundred and forty-four youngsters (6-15 years of age) were assigned, according to glycaemic control, to three study groups: (i) diabetic patients with poor glycaemic control [glycated haemoglobin (HbA1c ≥7.5%)] (n = 35); (ii) diabetic patients with good glycaemic control (HbA1c <7.5%) (n = 39); and (iii) healthy individuals (n = 70). Plaque, gingival inflammation, calculus and decayed, missing and filled surfaces (DMFS) indices were recorded. Salivary parameters were determined, and stimulated saliva was collected to allow detection and determination of the levels of oral Candida albicans and Streptococcus mutans by real-time polymerase chain reaction (PCR).

RESULTS

Significantly different amounts of plaque were found among the study groups (P = 0.024): youngsters with poor glycaemic control had significantly more plaque than youngsters in the other two groups. The gingival, calculus and DMFS indices were not significantly different among groups (P > 0.05). Candida albicans levels were not statistically significant different among groups, but the group with poor glycemic control showed an elevated frequency of detection. Streptococcus mutans was isolated from the oral cavity of 96 of the 144 individuals. A statistically significant difference in the level of S. mutans was found between the group with poor glycaemic control and the healthy control group (P = 0.032).

CONCLUSIONS

The results imply that youngsters with T1DM have a lower level of oral hygiene and are potentially at a higher risk of future oral disease, particularly when their metabolic disorder is uncontrolled. However, factors outside the oral cavity may also have a considerable impact on the initiation and progression of oral diseases.

Type 1 Diabetes Mellitus (Juvenile Diabetes) - A Review for the Pediatric Oral Health Provider

Objective: To describe the significance of type 1 diabetes mellitus (juvenile diabetes) to the pediatric oral health provider. Relevance: The oral health provider must be aware of type 1 diabetes mellitus (T1DM) characteristics, influence of on oral health, each patient pre-operative diabetic management, symptoms and treatment of hypo and hyper-glycemia, and the clinical implications before, during and after treatment of children with T1DM. Study design: A review of the scientific literature about the T1DM influence on dental development, caries prevalence, gingival and periodontal diseases, wound healing, salivary and taste dysfunction, oral infections, and the factors that must be taken in consideration before, during and after oral treatment of children with T1DM is presented. Conclusion: The increasing prevalence of T1DB in children strongly emphasizes the need for oral health providers to be aware of the complicacy of the treatment aimed to obtain and maintain acceptable blood glucose levels in diabetic children, the effect of diabetes on the oral cavity, the possible serious complications due to hypo- or hyper glycemia before, during and after oral treatments, the effect of stress on blood glucose levels, and the special behavioral interaction between the diabetic child, his/her family and the oral health providers.

Type 2 diabetes mellitus and oral Candida colonization: Analysis of risk factors in a Sri Lankan cohort

Aims: Oral candidiasis is a major oral manifestation of uncontrolled diabetes mellitus, and a number of cofactors are associated with the pathogenesis of this infection. Here, we describe the prevalence of oral Candida in a Sri Lankan cohort of type 2 diabetes mellitus and risk factors that predispose them to this common fungal infection. Methods: A case-control study was conducted in 250 diabetics with type 2 diabetes and 81 nondiabetic controls. Clinical and demographic data were collected using an interviewer administered questionnaire, and patient records. Oral rinse samples were collected to determine the candidal carriage, and the resultant yeast growth was quantified and speciated using multiplex-PCR and phenotypic analyses. Chi-square test (χ² test) and Fisher exact test were used for the determination of the significant relationships between risk factors and oral candidiasis. Results: The oral prevalence of Candida species among both groups was similar (81%) although a significantly higher proportion of diabetics (32.8%) yielded >2000 CFU/mL of yeasts compared with only 12.3% of the healthy controls (p < .05). Significant associations were noted between oral candidal carriage amongst diabetics, and (i) denture wearing, (ii) female gender and (iii) cigarette smoking (all, p < .05). Amongst both groups, C.albicans was the most common Candida species isolated followed by C. parapsilosis, C. tropicalis and C. glabrata. Conclusions: The oral infestation of Candida in our Sri Lankan cohort of diabetics is significantly higher than their healthy counterparts, and co-carriage of multiple yeast species is a common finding in the study population. As there are no previous such reports of the latter phenomenon particularly from the Asian region it is noteworthy, mainly in view of the recent data on the emergence of drug-resistant yeast species the world over.

Candida sp. Infections in Patients with Diabetes Mellitus

Candidiasis has increased substantially worldwide over recent decades and is a significant cause of morbidity and mortality, especially among critically ill patients. Diabetes mellitus (DM) is a metabolic disorder that predisposes individuals to fungal infections, including those related to Candida sp., due to a immunosuppressive effect on the patient. This review aims to discuss the latest studies regarding the occurrence of candidiasis on DM patients and the pathophysiology and etiology associated with these co-morbidities. A comprehensive review of the literature was undertaken. PubMed, Scopus, Elsevier’s ScienceDirect, and Springer’s SpringerLink databases were searched using well-defined search terms. Predefined inclusion and exclusion criteria were applied to classify relevant manuscripts. Results of the review show that DM patients have an increased susceptibility to Candida sp. infections which aggravates in the cases of uncontrolled hyperglycemia. The conclusion is that, for these patients, the hospitalization periods have increased and are commonly associated with the prolonged use of indwelling medical devices, which also increase the costs associated with disease management.

Drug interactions of meglitinide antidiabetics involving CYP enzymes and OATP1B1 transporter

Meglitinides such as repaglinide and nateglinide are useful to treat type 2 diabetes patients who follow a flexible lifestyle. They are short-acting insulin secretagogues and are associated with less risk of hypoglycemia, weight gain and chronic hyperinsulinemia compared with sulfonylureas. Meglitinides are the substrates of cytochrome P450 (CYP) enzymes and organic anion transporting polypeptide 1B1 (OATP1B1 transporter) and the coadministration of the drugs affecting them will result in pharmacokinetic drug interactions. This article focuses on the drug interactions of meglitinides involving CYP enzymes and OATP1B1 transporter. To prevent the risk of hypoglycemic episodes, prescribers and pharmacists must be aware of the adverse drug interactions of meglitinides.

Enterococcus faecalis bacteriocin EntV inhibits hyphal morphogenesis, biofilm formation, and virulence of Candida albicans

Enterococcus faecalis, a Gram-positive bacterium, and Candida albicans, a fungus, occupy overlapping niches as ubiquitous constituents of the gastrointestinal and oral microbiome. Both species also are among the most important and problematic, opportunistic nosocomial pathogens. Surprisingly, these two species antagonize each other's virulence in both nematode infection and in vitro biofilm models. We report here the identification of the E. faecalis bacteriocin, EntV, produced from the entV (ef1097) locus, as both necessary and sufficient for the reduction of C. albicans virulence and biofilm formation through the inhibition of hyphal formation, a critical virulence trait. A synthetic version of the mature 68-aa peptide potently blocks biofilm development on solid substrates in multiple media conditions and disrupts preformed biofilms, which are resistant to current antifungal agents. EntV68 is protective in three fungal infection models at nanomolar or lower concentrations. First, nematodes treated with the peptide at 0.1 nM are completely resistant to killing by C. albicans The peptide also protects macrophages and augments their antifungal activity. Finally, EntV68 reduces epithelial invasion, inflammation, and fungal burden in a murine model of oropharyngeal candidiasis. In all three models, the peptide greatly reduces the number of fungal cells present in the hyphal form. Despite these profound effects, EntV68 has no effect on C. albicans viability, even in the presence of significant host-mimicking stresses. These findings demonstrate that EntV has potential as an antifungal agent that targets virulence rather than viability.

The Aryl Hydrocarbon Receptor Governs Epithelial Cell Invasion during Oropharyngeal Candidiasis

Oropharyngeal candidiasis (OPC), caused predominantly by Candida albicans, is a prevalent infection in patients with advanced AIDS, defects in Th17 immunity, and head and neck cancer. A characteristic feature of OPC is fungal invasion of the oral epithelial cells. One mechanism by which C. albicans hyphae can invade oral epithelial cells is by expressing the Als3 and Ssa1 invasins that interact with the epidermal growth factor receptor (EGFR) on epithelial cells and stimulate endocytosis of the organism. However, the signaling pathways that function downstream of EGFR and mediate C. albicans endocytosis are poorly defined. Here, we report that C. albicans infection activates the aryl hydrocarbon receptor (AhR), leading to activation of Src family kinases (SFKs), which in turn phosphorylate EGFR and induce endocytosis of the fungus. Furthermore, treatment of oral epithelial cells with interferon gamma inhibits fungal endocytosis by inducing the synthesis of kynurenines, which cause prolonged activation of AhR and SFKs, thereby interfering with C. albicans-induced EGFR signaling. Treatment of both immunosuppressed and immunocompetent mice with an AhR inhibitor decreases phosphorylation of SFKs and EGFR in the oral mucosa, reduces fungal invasion, and lessens the severity of OPC. Thus, our data indicate that AhR plays a central role in governing the pathogenic interactions of C. albicans with oral epithelial cells during OPC and suggest that this receptor is a potential therapeutic target.

OPC is caused predominantly by the fungus C. albicans, which can invade the oral epithelium by several mechanisms. One of these mechanisms is induced endocytosis, which is stimulated when fungal invasins bind to epithelial cell receptors such as EGFR. Receptor binding causes rearrangement of epithelial cell microfilaments, leading to the formation of pseudopods that engulf the fungus and pull it into the epithelial cell. We discovered AhR acts via SFKs to phosphorylate EGFR and induce the endocytosis of C. albicans. Our finding that a small molecule inhibitor of AhR ameliorates OPC in mice suggests that a strategy of targeting host cell signaling pathways that govern epithelial cell endocytosis of C. albicans holds promise as a new approach to preventing or treating OPC.

Identification of Candida species in the oral cavity of diabetic patients

Background and Purpose:

Diabetic patients are more susceptible to oral candidiasis infection than non-diabetics due to the factors promoting oral carriage of Candida. Several factors can increase colonization of Candida species in the oral cavity such as xerostomia, which reduces the salivary flow and is a salivary pH disorder. In the current study, we aimed to identify and compare the colonization level of Candida spp. in the oral cavity of diabetic and non-diabetic groups.

Materials and Methods:

Swabs were taken from the mouth of 106 participants and were cultured on Sabouraud dextrose agar (SDA) medium. Likewise, the saliva samples were collected for salivary glucose and pH measurements. The study was performed during June 2014-September 2015 on two groups of diabetic patients (n=58) and non-diabetics (n=48) as the control group. The Candida spp. were identified with PCR-restriction fragment length polymorphism (RFLP) using the restriction enzymes HinfI and MspI and were differentiated by culture on CHROMagar Candida medium.

Results:

The frequency of Candida spp. was higher in diabetic patients compared to non-diabetics. The most frequent Candida spp. in the diabetic patients were Candidaalbicans (%36.2),C. Krusei (%10.4), C. Glabrata (%5.1), and C. tropcalis .(%3.4)Likewise, C. albicans was the most frequent species (%27) in the non-diabetic individuals. In this study, the results of both methods for identification of the isolates were consistent with each other.

Conclusion:

Xerostomia and disturbance of physiological factors including pH and glucose can promote overgrowth of Candida flora in the oral cavity. These factors are considered important predisposing factors for oral candidiasis in diabetic patients. In the present study, it was observed that application of CHROMagar Candida and PCR-RFLP methods at the same time contributes to more accurate identification of isolates.

Prevalence of oral Candida colonization in patients with diabetes mellitus

OBJECTIVES OF THE STUDY

We aimed to assess the prevalence of oral Candida colonization in patients with diabetes and its relationship with factors such as Candida species, serum glucose level, and the susceptibility rate of isolated yeasts to antifungals.

PATIENTS

Random samples were obtained from 113 patients with type 2 diabetes, 24 patients with type 1 diabetes, and 105 healthy controls.

MATERIALS AND METHODS

The samples were taken by swabbing the oral mucosa of patients with diabetes mellitus and healthy individuals. Afterwards the samples were inoculated onto CHROMagar-Candida. The growing colonies were counted, and the isolated yeasts were identified by PCR-RFLP and RapID methods. Various isolated species of Candida were also subjected to susceptibility testing of antibiotic drugs. Blood samples were taken to evaluate glycosylated hemoglobin (HbA1c).

RESULTS

Although the Candida carriage rate and density were statistically higher in diabetics than healthy individuals, no direct association was found between having high Candida-burden and glycosylated hemoglobin. The most commonly isolated species in both diabetics and controls was Candida albicans. Of the tested antifungal drugs, the highest rate of resistance was found against itraconazole, followed in frequency by ketoconazole and fluconazole.

CONCLUSIONS

This study identified a significant association between the poor glycemic control and the higher prevalence rates of Candida carriage and density in diabetic patients. In addition, a high prevalence of C. dubliniensis in diabetic patients was found, which might be misdiagnosed with its morphologically related species, C. albicans.

Transcriptomic analysis of vulvovaginal candidiasis identifies a role for the NLRP3 inflammasome

Treatment of vulvovaginal candidiasis (VVC), caused most frequently by Candida albicans, represents a significant unmet clinical need. C. albicans, as both a commensal and a pathogenic organism, has a complex and poorly understood interaction with the vaginal environment. Understanding the complex nature of this relationship is necessary for the development of desperately needed therapies to treat symptomatic infection. Using transcriptome sequencing (RNA-seq), we characterized the early murine vaginal and fungal transcriptomes of the organism during VVC. Network analysis of host genes that were differentially expressed between infected and naive mice predicted the activation or repression of several signaling pathways that have not been previously associated with VVC, including NLRP3 inflammasome activation. Intravaginal challenge of Nlrp3(-/-) mice with C. albicans demonstrated severely reduced levels of polymorphonuclear leukocytes (PMNs), alarmins, and inflammatory cytokines, including interleukin-1β (IL-1β) (the hallmarks of VVC immunopathogenesis) in vaginal lavage fluid. Intravaginal administration of wild-type (WT) mice with glyburide, a potent inhibitor of the NLRP3 inflammasome, reduced PMN infiltration and IL-1β to levels comparable to those observed in Nlrp3(-/-) mice. Furthermore, RNA-seq analysis of C. albicans genes indicated robust expression of hypha-associated secreted aspartyl proteinases 4, 5, and 6 (SAP4-6), which are known inflammasome activators. Despite colonization similar to that of the WT strain, ΔSAP4-6 triple and ΔSAP5 single mutants induced significantly less PMN influx and IL-1β during intravaginal challenge. Our findings demonstrate a novel role for the inflammasome in the immunopathogenesis of VVC and implicate the hypha-associated SAPs as major C. albicans virulence determinants during vulvovaginal candidiasis.

IMPORTANCE

Vaginitis, most commonly caused by the fungus Candida albicans, results in significant quality-of-life issues for all women of reproductive age. Recent efforts have suggested that vaginitis results from an immunopathological response governed by host innate immunity, although an explanatory mechanism has remained undefined. Using comprehensive genomic, immunological, and pharmacological approaches, we have elucidated the NLRP3 inflammasome as a crucial molecular mechanism contributing to host immunopathology. We have also demonstrated that C. albicans hypha-associated secreted aspartyl proteinases (SAP4-6 and SAP5, more specifically) contribute to disease immunopathology. Ultimately, this study enhances our understanding of the complex interplay between host and fungus at the vaginal mucosa and provides proof-of-principle evidence for therapeutic targeting of inflammasomes for symptomatic vulvovaginal candidiasis.

New signaling pathways govern the host response to C. albicans infection in various niches

Candida albicans, the major invasive fungal pathogen of humans, can cause both debilitating mucosal infections and fatal invasive infections. Understanding the complex nature of the host-pathogen interaction in each of these contexts is essential to developing desperately needed therapies to treat fungal infections. RNA-seq enables a systems-level understanding of infection by facilitating comprehensive analysis of transcriptomes from multiple species (e.g., host and pathogen) simultaneously. We used RNA-seq to characterize the transcriptomes of both C. albicans and human endothelial cells or oral epithelial cells during in vitro infection. Network analysis of the differentially expressed genes identified the activation of several signaling pathways that have not previously been associated with the host response to fungal pathogens. Using an siRNA knockdown approach, we demonstrate that two of these pathways-platelet-derived growth factor BB (PDGF BB) and neural precursor-cell-expressed developmentally down-regulated protein 9 (NEDD9)-govern the host-pathogen interaction by regulating the uptake of C. albicans by host cells. Using RNA-seq analysis of a mouse model of hematogenously disseminated candidiasis (HDC) and episodes of vulvovaginal candidiasis (VVC) in humans, we found evidence that many of the same signaling pathways are activated during mucosal (VVC) and/or disseminated (HDC) infections in vivo. Our analyses have uncovered several signaling pathways at the interface between C. albicans and host cells in various contexts of infection, and suggest that PDGF BB and NEDD9 play important roles in this interaction. In addition, these data provide a valuable community resource for better understanding host-fungal pathogen interactions.

Host cell invasion by medically important fungi

To infect the host and cause disease, many medically important fungi invade normally nonphagocytic host cells, such as endothelial cells and epithelial cells. Host cell invasion is a two-step process consisting of adherence followed by invasion. There are two general mechanisms of host cell invasion, induced endocytosis and active penetration. Furthermore, fungi can traverse epithelial or endothelial cell barriers either by proteolytic degradation of intercellular tight junctions or via a Trojan horse mechanism in which they are transported by leukocytes. Although these mechanisms of host cell invasion have been best studied using Candida albicans and Cryptococcus neoformans, it is probable that other invasive fungi also use one or more of these mechanisms to invade host cells. Identification of these invasion mechanisms holds promise to facilitate the development of new approaches to inhibit fungal invasion and thereby prevent disease.

Glucose directly promotes antifungal resistance in the fungal pathogen, Candida spp

Effects of glucose on the susceptibility of antifungal agents were investigated against Candida spp. Increasing the concentration of glucose decreased the activity of antifungal agents; voriconazole was the most affected drugs followed by amphotericin B. No significant change has been observed for anidulafungin. Biophysical interactions between antifungal agents with glucose molecules were investigated using isothermal titration calorimetry, Fourier transform infrared, and (1)H NMR. Glucose has a higher affinity to bind with voriconazole by hydrogen bonding and decrease the susceptibility of antifungal agents during chemotherapy. In addition to confirming the results observed in vitro, theoretical docking studies demonstrated that voriconazole presented three important hydrogen bonds and amphotericin B presented two hydrogen bonds that stabilized the glucose. In vivo results also suggest that the physiologically relevant higher glucose level in the bloodstream of diabetes mellitus mice might interact with the available selective agents during antifungal therapy, thus decreasing glucose activity by complex formation. Thus, proper selection of drugs for diabetes mellitus patients is important to control infectious diseases.

Cigarette smoke-exposed Candida albicans increased chitin production and modulated human fibroblast cell responses

The predisposition of cigarette smokers for development of respiratory and oral bacterial infections is well documented. Cigarette smoke can also contribute to yeast infection. The aim of this study was to investigate the effect of cigarette smoke condensate (CSC) on C. albicans transition, chitin content, and response to environmental stress and to examine the interaction between CSC-pretreated C. albicans and normal human gingival fibroblasts. Following exposure to CSC, C. albicans transition from blastospore to hyphal form increased. CSC-pretreated yeast cells became significantly (P < 0.01) sensitive to oxidation but significantly (P < 0.01) resistant to both osmotic and heat stress. CSC-pretreated C. albicans expressed high levels of chitin, with 2- to 8-fold recorded under hyphal conditions. CSC-pretreated C. albicans adhered better to the gingival fibroblasts, proliferated almost three times more and adapted into hyphae, while the gingival fibroblasts recorded a significantly (P < 0.01) slow growth rate but a significantly higher level of IL-1β when in contact with CSC-pretreated C. albicans. CSC was thus able to modulate both C. albicans transition through the cell wall chitin content and the interaction between C. albicans and normal human gingival fibroblasts. These findings may be relevant to fungal infections in the oral cavity in smokers.

Pediatric soft tissue oral lesions

This article provides an overview of common color changes and soft tissue oral nodular abnormalities in children and adolescents. The clinical presentation and treatment options to address these conditions are presented in a concise approach, highlighting key features relevant to the oral health care professional.

Cigarette smoke condensate increases C. albicans adhesion, growth, biofilm formation, and EAP1, HWP1 and SAP2 gene expression

BACKGROUND

Smokers are more prone to oral infections than are non-smokers. Cigarette smoke reaches the host cells but also microorganisms present in the oral cavity. The contact between cigarette smoke and oral bacteria promotes such oral diseases as periodontitis. Cigarette smoke can also modulate C. albicans activities that promote oral candidiasis. The goal of this study was to investigate the effect of cigarette smoke condensate on C. albicans adhesion, growth, and biofilm formation as well as the activation of EAP1, HWP1 and secreted aspartic protease 2.

RESULTS

Cigarette smoke condensate (CSC) increased C. albicans adhesion and growth, as well as biofilm formation. These features may be supported by the activation of certain important genes. Using quantitative RT-PCR, we demonstrated that CSC-exposed C. albicans expressed high levels of EAP1, HWP1 and SAP2 mRNA and that this gene expression increased with increasing concentrations of CSC.

CONCLUSION

CSC induction of C. albicans adhesion, growth, and biofilm formation may explain the increased persistence of this pathogen in smokers. These findings may also be relevant to other biofilm-induced oral diseases.

Characterization of the oral fungal microbiota in smokers and non-smokers

This study aimed to assess the effect of smoking on the biodiversity of the oral fungal microbiota of healthy young subjects, using an improved culture method that assesses both total and pathogenic viable fungi. Forty individuals (20 smokers and 20 non-smokers) were selected. All individuals presented fungal growth (100% for molds and 92.5% for yeasts), a prevalence higher than previously reported. The most commonly occurring molds were Penicillium sp., Aspergillus sp., and Cladosporium sp. Smokers presented significantly higher levels of yeasts and pathogenic molds than did non-smokers. No differences in fungal prevalence and diversity were observed in smokers and non-smokers following a 30-wk observation period. In conclusion, tobacco smoking may alter the oral mycobiota and facilitate colonization of the oral cavity with yeasts and pathogenic molds. The effect of chronic fungal colonization on the oral health of tobacco smokers cannot be neglected.

Prevalence of Candida spp. during radiographic examination in Diabetes mellitus patients

INTRODUCTION: It is suggested that individuals with diabetes are more susceptible to Candida infections than healthy people, especially if periodontal infection is associated. OBJECTIVE: This study evaluated the prevalence of colonization by Candida spp. during radiographic examination in diabetic and non-diabetic patients. MATERIAL AND METHODS: Twenty-six patients with type 2 diabetes mellitus and 20 patients without diabetes mellitus, presenting chronic periodontitis and presence of Candida spp. in saliva were evaluated. During radiographic examination, samples of saliva were collected from: oral mucosa, conventional radiographic periapical film, digital x-ray sensor (CDR), and bite block of the receptor-positioning device. Colony forming units (cfu/mL) and identification of Candida yeasts were assessed. RESULT: Oral mucosa from both groups showed the highest colonization with Candida spp. if compared with others surfaces collected (p < 0.05). In diabetic patients, the mucosa of the upper left regions showed higher levels of colonization. In non-diabetic patients, the upper right molar region showed the highest level of colonization during the examination of the receptor-positioning device, the sensor and the non-sensitive film. Candida spp. levels in saliva were similar between diabetics (mean = 3.0 × 10(6)) and non-diabetics (mean = 3.8 × 10(6)). CONCLUSION: No difference in Candida spp. colonization (cfu/mL) in diabetics and non-diabetic patients was observed for the five collected surfaces and the simulated radiographic region. Candida albicans was the prevalent species of Candida spp. found on all the samples.

Divergent targets of Candida albicans biofilm regulator Bcr1 in vitro and in vivo

Candida albicans is a causative agent of oropharyngeal candidiasis (OPC), a biofilm-like infection of the oral mucosa. Biofilm formation depends upon the C. albicans transcription factor Bcr1, and previous studies indicate that Bcr1 is required for OPC in a mouse model of infection. Here we have used a nanoString gene expression measurement platform to elucidate the role of Bcr1 in OPC-related gene expression. We chose for assays a panel of 134 genes that represent a range of morphogenetic and cell cycle functions as well as environmental and stress response pathways. We assayed gene expression in whole infected tongue samples. The results sketch a portrait of C. albicans gene expression in which numerous stress response pathways are activated during OPC. This one set of experiments identifies 64 new genes with significantly altered RNA levels during OPC, thus increasing substantially the number of known genes in this expression class. The bcr1Δ/Δ mutant had a much more limited gene expression defect during OPC infection than previously reported for in vitro growth conditions. Among major functional Bcr1 targets, we observed that ALS3 was Bcr1 dependent in vivo while HWP1 was not. We used null mutants and complemented strains to verify that Bcr1 and Hwp1 are required for OPC infection in this model. The role of Als3 is transient and mild, though significant. Our findings suggest that the versatility of C. albicans as a pathogen may reflect its ability to persist in the face of multiple stresses and underscore that transcriptional circuitry during infection may be distinct from that detailed during in vitro growth.

Mouse model of oropharyngeal candidiasis

Oropharyngeal candidiasis is a frequent cause of morbidity in patients with defects in cell-mediated immunity or saliva production. Animal models of this infection are important for studying disease pathogenesis and evaluating vaccines and antifungal therapies. Here we describe a simple mouse model of oropharyngeal candidiasis. Mice are rendered susceptible to oral infection by injection with cortisone acetate and then inoculated by placing a swab saturated with Candida albicans sublingually. This process results in a reproducible level of infection, the histopathology of which mimics that of pseudomembranous oropharyngeal candidiasis in humans. By using this model, data are obtained after 5-9 d of work.

Candida invasion and influences in smoking patients with multiple oral leucoplakias--a retrospective study

Treating patients with multiple oral leucoplakias (MOLs) who smoke is more difficult and complicated than treating those with single oral leucoplakia (SOL). Removing the aetiological factors causing MOL can effectively prevent its recurrence. The aim was to study the infection by and influences of Candida in smoking patients with MOLs. A retrospective study was conducted on 136 smoking patients who had clinicopathological OLs. Among these patients, 73 lesions in 31 patients were MOLs, while 105 patients had SOLs. All patients were treated by complete resection. All specimens were tested for epithelial dysplasia, and stained with periodic acid-Schiff reagent. The rate of MOL concurrence with candidal infection was higher than that of SOLs. The incidence of Candida associated with MOLs was higher for recurrent than for non-recurrent lesions. The disease-free time was shorter in MOL patients with candidal infection. Moreover, MOLs with candidal infection were more likely to have an increasing ratio to combine with epithelial dysplasia. Candida is an important risk factor in smoking patients with MOLs. Microscopic and fungal examinations of those lesions should permit a detailed diagnosis in such patients and for long-term predictive assessments.

Hydrolytic enzyme production is associated with Candida albicans biofilm formation from patients with type 1 diabetes

Oral candidosis is common in patients with diabetes mellitus, as yeasts, particularly Candida albicans, have the propensity to colonise, form biofilms and release hydrolytic enzymes which cause inflammation. This study aimed to investigate these characteristics in isolates from three groups of patients with type 1 diabetes: individuals with better controlled diabetes (BCD; >or=6 <8%), individuals with poorly controlled diabetes (PCD; >or=8%) and non-diabetics (ND; HbA(1c) <5.9%). The biomass (Bm), phospholipase (P(z)), haemolysin (H(z)) and proteinase (Pr(z)) were assessed using a microtitre biofilm assay and agar-based hydrolytic enzyme assays. Biofilm formation was significantly increased in the PCD group compared to ND and BCD groups (P < 0.05). No significant differences in P(z) levels were observed between groups, whereas both H(z) and Pr(z) were significantly greater in the diabetes groups than in the healthy control group (P < 0.05). Statistically significant correlations were found to exist between the HbA(1c) levels of the patients and the Bm (R = 0.384; P = 0.033), haemolysin activity (R = -0.455; P = 0.010) and proteinase activity (R = -0.531; P = 0.002). There was no apparent correlation between the Bm and P(z) activity (R = -0.305; P = 0.053) or H(z) activity (R = -0.100; P = 0.296). However, a negative correlation was found between Bm and Pr(z) values (R = -0.343; P = 0.030). These data suggest that biofilm formation is likely to play a role in the pathogenicity of oral candidosis, and in patients with diabetes, this may be due to the ability of C. albicans to adapt to the altered physiological environment. The production of hydrolytic enzymes is independently associated with this growth modality.

The Relationship between Tobacco Smoking and Oral Colonization with Candida Species

Aim

The aim of this study was to assess and compare the quantitative and qualitative oral colonization of Candida species between a group of healthy tobacco smokers and a comparable group of nonsmokers, and to investigate a possible correlation between oral candidal colonization and the quantity or duration of the smoking habit.

Methods and Materials

Fifty smokers and 50 nonsmokers were included in the study. Candida species were isolated using the concentrated oral rinse (COR) technique and identified using the germ tube test and API 20 C AUX yeast identification system.

Results

Overall candidal transmission was 84 percent. Candida species were isolated from 42 (84 percent) of the smokers and 37 (74 percent) of the nonsmokers (p>0.05). The mean CFU/ml were 333 (SD=358) and 268 (SD=332), respectively (p>0.05).

Conclusion

Tobacco smoking did not appear to increase oral colonization with Candida species in healthy subjects.

Clinical Significance

The effects of smoking on oral tissues and the mechanisms by which Candida proliferate intra-orally as a result of cigarette smoking warrant additional study.

Citation

Darwazeh AM, Al-Dwairi ZN, Al-Zwairi AA. The Relationship between Tobacco Smoking and Oral Colonization with Candida Species. J Contemp Dent Pract [Internet]. 2010 May; 11(3):017-024. Available from: http://www.thejcdp. com/journal/view/volume11-issue3-al_dwairi

Candidal colonization, strain diversity, and antifungal susceptibility among adult diabetic patients

BACKGROUND AND OBJECTIVES

Candidal colonization in diabetics is a matter of debate. The aim of this study is to investigate oral candidal colonization, strain diversity, antifungal susceptibility, and the influence of local and systemic host factors on candidal colonization in adult diabetics.

METHODS

We conducted a case-control study that compared 150 diabetics (49 type 1, 101 type 2) with 50 healthy controls. Two salivary samples were collected, using the oral rinse sampling method: one for salivary flow rate and pH determination, and the other for candidal colonization assessment. The candidal isolates were identified and tested in vitro for antifungal susceptibility using the commercial kit, Candifast. The relationship between specific host factors and candidal colonization was also investigated.

RESULTS

Diabetics had a higher candidal carriage rate compared to controls, but not density. Candida albicans was the most frequently isolated species, but diabetics had a variety of other candidal species present. None of the control samples were resistant to any tested antifungal, while the diabetic samples had differing resistances to azole antifungals. Although there was a significant positive correlation between glycemic control and candidal colonization in type 2 diabetics, there was a negative correlation between salivary pH and candidal carriage in the controls versus density in type 2 diabetics.

CONCLUSIONS

Diabetic patients not only had a higher candidal carriage rate, but also a variety of candidal species that were resistant to azole antifungals. Oral candidal colonization was significantly associated with glycemic control, type of diabetes, and salivary pH.

Distribution and hydrolytic enzyme characteristics of Candida albicans strains isolated from diabetic patients and their non-diabetic consorts

INTRODUCTION

The aim of this study was to investigate the oral colonization profile of Candida albicans strains isolated from diabetic patients and their non-diabetic consorts. In addition hydrolytic enzyme activity of these isolates was analysed.

METHODS

The genetic diversity of C. albicans oral isolates from 52 couples was established using isoenzyme marker and cluster analysis. Hydrolytic enzyme characteristics, namely secreted aspartyl proteinases (SAPs) and phospholipases (PLs) were also analysed.

RESULTS

Simultaneous colonization by C. albicans was observed in the consorts of 12 couples (23.1%). Patterns of monoclonal and polyclonal oral colonization by C. albicans strains were identified and the coexistence of identical or highly related strains was observed in both members of eight couples. The genetic diversity observed in the total yeast population revealed four large, genetically distinct groups (A to D) and the coexistence of strains in couples or consorts conjugally unrelated. SAP and PL activity was observed in the majority of C. albicans isolates without any association to particular strain, strain clusters (highly related isolates), or clinical characteristics of the consorts (diabetic, non-diabetic, and gender).

CONCLUSION

Possible sources of transmission and oral propagation of groups (clusters) of strains of C. albicans can occur between diabetic and non-diabetic consorts. A conjugal genotypic identity exists in most C. albicans-positive couples, that is, both consorts share identical or highly related strains; however, this identity is not couple-specific as seen by the coexistence of clusters in couples and unrelated consorts.

Interactions of Candida albicans with epithelial cells

The fungus, Candida albicans, interacts with epithelial cells in the human host both as a normal commensal and as an invasive pathogen. It has evolved multiple complementary mechanisms to adhere to epithelial cells. Adherent C. albicans cells can invade epithelial surfaces both by penetrating into individual epithelial cells, and by degrading interepithelial cell junctions and passing between epithelial cells. Invasion into epithelial cells is mediated by both induced endocytosis and active penetration, whereas degradation of epithelial cell junction proteins, such as E-cadherin, occurs mainly via proteolysis by secreted aspartyl proteinases. C. albicans invasion of epithelial cells results in significant epithelial cell damage, which is probably induced by lytic enzymes, such as proteases and phospholipase secreted by the organism. Future challenges include identifying the epithelial cell targets of adhesins and invasins, and determining the mechanisms by which C. albicans actively penetrates epithelial cells and induces epithelial cell damage.

Transcriptional responses of candida albicans to epithelial and endothelial cells

Candida albicans interacts with oral epithelial cells during oropharyngeal candidiasis and with vascular endothelial cells when it disseminates hematogenously. We set out to identify C. albicans genes that govern interactions with these host cells in vitro. The transcriptional response of C. albicans to the FaDu oral epithelial cell line and primary endothelial cells was determined by microarray analysis. Contact with epithelial cells caused a decrease in transcript levels of genes related to protein synthesis and adhesion, whereas contact with endothelial cells did not significantly influence any specific functional category of genes. Many genes whose transcripts were increased in response to either host cell had not been previously characterized. We constructed mutants with homozygous insertions in 22 of these uncharacterized genes to investigate their function during host-pathogen interaction. By this approach, we found that YCK2, VPS51, and UEC1 are required for C. albicans to cause normal damage to epithelial cells and resist antimicrobial peptides. YCK2 is also necessary for maintenance of cell polarity. VPS51 is necessary for normal vacuole formation, resistance to multiple stressors, and induction of maximal endothelial cell damage. UEC1 encodes a unique protein that is required for resistance to cell membrane stress. Therefore, some C. albicans genes whose transcripts are increased upon contact with epithelial or endothelial cells are required for the organism to damage these cells and withstand the stresses that it likely encounters during growth in the oropharynx and bloodstream.

An elderly case of type 2 diabetes which developed in association with oral and esophageal candidiasis

A 75-year-old woman who had been healthy except for mild glycemia and lipidemia discovered three and a half months before admission experienced severe dysphagia secondary to oral and esophageal candidiasis. She eventually developed diabetic hyperosmolar syndrome and ketoacidosis. Since anti-GAD antibody was negative and her diabetes was controlled with a moderate dose of insulin, we made a diagnosis of type 2 diabetes. Her only risk factors for candidiasis were hyperglycemia, age, and continuous denture use. The fact that her diabetes developed in association with oral candidiasis supports the hypothesis that there is a bidirectional interrelationship between diabetes and oral infection.

Species diversity of yeast in oral colonization of insulin-treated diabetes mellitus patients

The aim of this study was to investigate oral yeast colonization, antifungal susceptibility and strain diversity in insulin-dependent diabetes mellitus patients (175), as well as to evaluate the influence of dental prostheses. Oral rinse samples were cultured on selective media, in order to isolate, count and identify the yeasts recovered. More than half of the diabetic subjects (53%) carried significant amounts of Candida cells in the buccal cavity and these organisms were recovered at higher densities in diabetics wearing dentures. A total of 93 yeast strains were isolated from these patients, including: Candida spp. (n = 89); Pichia (n = 02); Trichosporon (n = 1), and Geotrichum (n = 1). C. albicans represented 56% of these strains, non-albicans Candida 39.8%, and other genera of yeast 4.3%. C. albicans was prevalent, followed by C. parapsilosis, C. tropicalis, C. glabrata, C. krusei, C. rugosa and C. guilliermondii. Agar disk-diffusion tests of the susceptibility of non-albicans Candida and other genera of yeast to fluconazole showed resistance in 21.9%, mainly in C. rugosa (100%), C. glabrata (57%) and C. krusei (50%). Local oral factors, such as the presence of dentures, in association with diabetes, seemed to have the effect of increasing the amount and variety of Candida species in the oral cavities, mainly those with lower drug susceptibilities.

Candida species in stool, symptoms and complaints in general practice ? a cross-sectional study of 308 outpatients

Patients with unspecific symptoms were sometimes tested for Candida. In case of findings of this yeast-like fungus in their stools they often were labelled with the diagnosis of a "Candida-syndrome". This comprises headache, weakness, flatulence, ravenous appetite for sweets, itching skin and several more unspecific symptoms. All 500 randomly sampled patients in 12 mainly naturopathic practices were asked to take part. In case of participation, they received stool-tubes and questionnaires to be answered during the waiting-time by the patients themselves. We asked for details of lifestyle, diseases and a number of unspecific symptoms. The stool-tubes were sent to a microbiological lab within 24 h after being filled. About one-third of all 308 participants carried Candida albicans in their stools. This finding is regarded as normal. Smoking habits were highly associated to Candida: 45 of the 78 smokers (58%), but only 68 of the 230 (29%) non-smokers were Candida positive, P < 0.0001. Three more results were associated with Candida-positive stools: Candida-vaginitis, allergies against food and allergies in general. Hints of a Candida-syndrome could not be found. The relation with smoking cigarettes is a new result. Associations to Candida-vaginitis and allergies were described before.

In vitro evaluation of virulence attributes of Candida spp. isolated from patients affected by diabetes mellitus

BACKGROUND

Diabetes mellitus is a common disease found worldwide and it has been previously suggested that oral candidal infections may be more frequent or severe in patients with this disease. Systemic and local factors may influence the balance between the host and yeasts, and favour the transformation of Candida isolates from commensal to pathogenic microorganisms. Candida species have developed specific virulence mechanisms that confer the ability to colonise host surfaces, to invade deeper host tissue, or to evade host defences. Few studies have investigated the expression of the virulence attributes of oral Candida isolates in patients with diabetes mellitus.

MATERIAL AND METHODS

The in vitro extracellular proteinase production and the in vitro ability to adhere to fibronectin of 229 Candida isolates of two geographic different groups of patients with diabetes mellitus and of healthy subjects were assessed.

RESULTS

Candida isolates of patients with diabetes mellitus expressed a higher ability to adhere than those of healthy subjects. Higher levels of adhesion were also recorded in patients with a lower oral Candida colonisation. No differences were observed in the in vitro expression of extracellular proteinase of Candida isolates of patients with diabetes mellitus and those of non-diabetic subjects. Isolates of patients with type 2 diabetes mellitus expressed greater levels of proteinase than isolates of type 1 diabetes mellitus.

CONCLUSIONS

Diabetes mellitus could be considered as an additional variable that may influence not only oral Candida carriage but also the ability of isolates to enhance the expression of virulence attributes.

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.