Recovery of Candida dubliniensis and other Candida species from the oral cavity of subjects with periodontitis who had well-controlled and poorly controlled type 2 diabetes: a pilot study

Oral Yeasts Carriage in Prediabetic Smokers and Nonsmokers

BACKGROUND

Habitual smoking and prediabetes are independent risk factors for increased oral yeasts carriage (OYC); however, no studies have compared OYC amongst cigarette smokers and nonsmokers with and without prediabetes. The aim was to fill this research gap.

METHODS

Ninety-two participants were included and categorised into 4 groups: group 1, prediabetic (haemoglobin A1c [HbA1c] levels, 5.7%-6.4%) cigarette smokers; group 2, cigarette smokers without prediabetes; group 3, prediabetic nonsmokers; and group 4, nonsmokers without prediabetes. Patient demographics and HbA1c levels were recorded. Data on duration of smoking habit (pack-years) and family history of smoking were collected. Information on daily toothbrushing and flossing and most recent visit to a dentist/dental hygienist was gathered. Clinical and radiographic periodontal examination was performed and unstimulated whole salivary flow rate (UWSFR) was determined. OYC was assessed using the oral rinse sampling method. Power analysis was done, and group comparisons were performed. Logistic regression analysis was performed and P values <5% reflected statistical significance.

RESULTS

Respectively, 23, 24, 22, and 23 individuals with comparable mean ages were included in groups 1, 2, 3, and 4. In groups 1 and 2, participants had a smoking history of (mean ± SD) 24.7 ± 3.2 and 10.6 ± 2.5 pack-years. Plaque index, clinical attachment loss, and probing depth were higher in groups 1 (P < .05), 2 (P < .05), and 3 (P < .05) than in group 4. Number of missing teeth was significantly higher in group 1 compared with groups 2 (P < .05), 3 (P < .05), and 4 (P < .05). There was no difference in UWSFR amongst the groups. OYC was greater in group 1 than in groups 2 (P < .05), 3 (P < .05), and 4 (P < .05). OYC was greater in groups 2 (P < .05) and 3 (P < .05) than in group 4.

CONCLUSIONS

In prediabetic cigarette smokers, OYC appears to be influenced by hyperglycaemia, whilst in nondiabetic smokers, the severity of periodontal inflammation appears to be the determining factor in OYC.

Candida albicans Induces Oral Microbial Dysbiosis and Promotes Oral Diseases

Candida albicans are ubiquitous fungal organisms that colonize the oral cavity of healthy individuals without causing disease. C. albicans is an opportunistic microorganism with several virulent factors that influence the inflammatory process and allow it to invade tissues, evade host defense mechanisms, and release toxins, facilitating proliferation and degradation. At present, increasing emphasis is placed on polymicrobial interactions between C. albicans and various bacterial pathogens. Such interaction is mutually beneficial for both parties: it is competitive and antagonistic. Their complex interaction and colonization in the oral cavity serve as the basis for several oral diseases. The dispersion of C. albicans in saliva and the systemic circulation is noted in association with other bacterial populations, suggesting their virulence in causing disease. Hence, it is necessary to understand fungal-bacterial interactions for early detection and the development of novel therapeutic strategies to treat oral diseases. In this paper, we review the mutualistic interaction of C. albicans in oral biofilm formation and polymicrobial interactions in oral diseases. In addition, C. albicans virulence in causing biofilm-related oral diseases and its presence in saliva are discussed.

Candida species in periodontitis: A new villain or a new target?

OBJECTIVES

Recent research indicated that fungi might have a role in periodontitis alongside traditional periodontal pathogens. This state-of-the-art narrative review explores current concepts on the involvement of Candida species in periodontitis, and suggests the potential for ecological management of this disease.

DATA, SOURCES AND STUDY SELECTION

A literature search was conducted for a narrative review on Web of Science, PubMed, Medline and Scopus about periodontitis associated with Candida species. Published articles, including case reports, case series, observational and interventional clinical trials, and critical appraisals of the literature were retrieved and reviewed.

CONCLUSIONS

Several factors predispose individuals to periodontitis associated with Candida species. These include systemic diseases that lead to immunosuppression and oral environment changes such as cigarette smoking. While a consistent significant increase in the detection rate of Candida species in patients with periodontitis has not been universally observed, there is evidence linking Candida species to the severity of periodontitis and their potential to worsen the condition. Candida species may participate in the development of periodontitis in various ways, including cross-kingdom interactions with periodontal pathogens, changes in the local or systemic environment favoring the virulence of Candida species, and interactions between Candida-bacteria and host immunity.

CLINICAL SIGNIFICANCE

Mechanical plaque control is the most common treatment for periodontitis, but its effectiveness may be limited, particularly when dealing with systemic risk factors. Understanding the specific role of Candida in periodontitis illuminates innovative approaches for managing the ecological balance in periodontal health.

Association between Candida species and periodontal disease: A systematic review

Periodontal diseases result in the inflammation of the supporting structures of the teeth, thereby leading to attachment loss and bone loss. One of the main etiological factors responsible for this condition is the presence of subgingival biofilms, comprising microorganisms, namely bacteria, viruses, and fungi. Candida species is one of the fungi reported to be found in periodontal disease which is suggestive of the presence of an association between these variables. The aim of this systematic review was to evaluate the association of Candida species with periodontal disease and determine the prevalence of these species in the patients affected with this disease. The articles related to the subject of interest were searched in several databases, including the PubMed, Web of Science, Google Scholar Medline, Embase, Cochrane Library, and Scopus. The search process was accomplished using three keywords, namely ‘‘Candida species’’, ‘‘Chronic periodontitis’’, and ‘‘Gingivitis’’. All the identified studies were comprehensively evaluated for the association of Candida species with periodontal disease. This systematic review included 23 articles, which assessed the prevalence of Candida species in periodontal diseases. The results of 21 studies were indicative of a positive association between Candida species and periodontal diseases. Accordingly, it was concluded that there is a strong association between the presence of Candida species and periodontal diseases

Candida albicans Shields the Periodontal Killer Porphyromonas gingivalis from Recognition by the Host Immune System and Supports the Bacterial Infection of Gingival Tissue

Candida albicans is a pathogenic fungus capable of switching its morphology between yeast-like cells and filamentous hyphae and can associate with bacteria to form mixed biofilms resistant to antibiotics. In these structures, the fungal milieu can play a protective function for bacteria as has recently been reported for C. albicans and a periodontal pathogen-Porphyromonas gingivalis. Our current study aimed to determine how this type of mutual microbe protection within the mixed biofilm affects the contacting host cells. To analyze C. albicans and P. gingivalis persistence and host infection, several models for host-biofilm interactions were developed, including microbial exposure to a representative monocyte cell line (THP1) and gingival fibroblasts isolated from periodontitis patients. For in vivo experiments, a mouse subcutaneous chamber model was utilized. The persistence of P. gingivalis cells was observed within mixed biofilm with C. albicans. This microbial co-existence influenced host immunity by attenuating macrophage and fibroblast responses. Cytokine and chemokine production decreased compared to pure bacterial infection. The fibroblasts isolated from patients with severe periodontitis were less susceptible to fungal colonization, indicating a modulation of the host environment by the dominating bacterial infection. The results obtained for the mouse model in which a sequential infection was initiated by the fungus showed that this host colonization induced a milder inflammation, leading to a significant reduction in mouse mortality. Moreover, high bacterial counts in animal organisms were noted on a longer time scale in the presence of C. albicans, suggesting the chronic nature of the dual-species infection.

Adhesive protein-mediated cross-talk between Candida albicans and Porphyromonas gingivalis in dual species biofilm protects the anaerobic bacterium in unfavorable oxic environment

The oral cavity contains different types of microbial species that colonize human host via extensive cell-to-cell interactions and biofilm formation. Candida albicans-a yeast-like fungus that inhabits mucosal surfaces-is also a significant colonizer of subgingival sites in patients with chronic periodontitis. It is notable however that one of the main infectious agents that causes periodontal disease is an anaerobic bacterium-Porphyromonas gingivalis. In our study, we evaluated the different strategies of both pathogens in the mutual colonization of an artificial surface and confirmed that a protective environment existed for P. gingivalis within developed fungal biofilm formed under oxic conditions where fungal cells grow mainly in their filamentous form i.e. hyphae. A direct physical contact between fungi and P. gingivalis was initiated via a modulation of gene expression for the major fungal cell surface adhesin Als3 and the aspartic proteases Sap6 and Sap9. Proteomic identification of the fungal surfaceome suggested also an involvement of the Mp65 adhesin and a "moonlighting" protein, enolase, as partners for the interaction with P. gingivalis. Using mutant strains of these bacteria that are defective in the production of the gingipains-the proteolytic enzymes that also harbor hemagglutinin domains-significant roles of these proteins in the formation of bacteria-protecting biofilm were clearly demonstrated.

Subgingival areas as potential reservoirs of different Candida spp in type 2 diabetes patients and healthy subjects

OBJECTIVES

The aim of this cross-sectional observational study was to compare the prevalence of different oral Candida spp. in patients with Type 2 Diabetes and chronic periodontitis in two oral sites: dorsal surface of the tongue and subgingival area. In order to determine subgingival areas as potential reservoirs of yeasts, this study aimed to find differences in the yeasts' detection between the dorsum of the tongue, as the oral site most commonly inhabited with microorganisms, and subgingival samples. Additionally, potential predictors for the yeasts prevalence were determined.

MATERIAL AND METHODS

Subjects (N = 146) were divided into four groups: group A- healthy individuals without periodontitis, group B- healthy individuals with chronic periodontitis, group C- Type 2 Diabetes patients with good glycoregulation and Chronic periodontitis and group D- Type 2 Diabetes patients with poor glycoregulation and Chronic periodontitis. Samples were obtained from the tongue by swabbing. Subgingival plaque samples were taken by paper points and periodontal curette. Isolation and identification of different Candida spp. was done using ChromAgar medium. In addition, germ-tube production and carbohydrate assimilation tests were performed.

RESULTS

The prevalence of Candida spp. was higher in diabetics with poor glycoregulation. The most frequently isolated species was Candida albicans followed by Candida glabrata and Candida tropicalis. In 15.6% of cases, Candida spp. was present in the subgingival area while absent on the tongue. Multivariate regression model showed that HbA1c was Candida spp. predictor for both locations.

CONCLUSIONS

Our results confirmed that there are Candida spp. carriers among subjects with clinically healthy oral mucosa. Also, this study identified subgingival areas as potential reservoirs of these pathogenic species. Glycoregulation has been recognized as a positive predictor factor of Candida spp.

Diversity, frequency and antifungal resistance of Candida species in patients with type 2 diabetes mellitus

OBJECTIVE

To determine number, species of Candida and Candida resistance to antifungal therapy according to the metabolic control state and the associated salivary changes in patients with type 2 diabetes mellitus (DM2).

MATERIALS AND METHODS

Samples of non-stimulated saliva were collected from 52 patients with DM2. Salivary pH was measured and cultured on Sabouraud glucose agar and the values of CFU/ml were calculated. The species were presumptively identified using CHROMagar Candida^® plates, and identification was confirmed by polymerase chain reaction (PCR). C. albicans isolates were cultured on SGA tetracycline agar with nystatin and fluconazole diffusion disks to measure susceptibility.

RESULTS

Sixty six percent of the yeasts isolated were Candida albicans, followed by C. glabrata (20.7%). In patients with decompensated DM2, there was an inverse association between HbA1c value and salivary pH. At higher levels of salivary acidification, a greater diversity and quantity of yeasts of the genus Candida were observed. With nystatin, higher inhibition was observed at lower pH.

CONCLUSIONS

The antifungal therapies could be more effective if it consider, qualitative salivary characteristics as pH, that could determine the susceptibility of species of Candida to at least to nystatin, which is the most used antifungal for treatment to oral candidiasis in patients with DM2.

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.

Unisexual reproduction

Sexual reproduction is ubiquitous throughout the eukaryotic kingdom, but the capacity of pathogenic fungi to undergo sexual reproduction has been a matter of intense debate. Pathogenic fungi maintained a complement of conserved meiotic genes but the populations appeared to be clonally derived. This debate was resolved first with the discovery of an extant sexual cycle and then unisexual reproduction. Unisexual reproduction is a distinct form of homothallism that dispenses with the requirement for an opposite mating type. Pathogenic and nonpathogenic fungi previously thought to be asexual are able to undergo robust unisexual reproduction. We review here recent advances in our understanding of the genetic and molecular basis of unisexual reproduction throughout fungi and the impact of unisex on the ecology and genomic evolution of fungal species.

The effect of glycemic control on Candida colonization of the tongue and the subgingival plaque in patients with type II diabetes and periodontitis

OBJECTIVES

Identify the relationship between the tongue and subgingival plaque Candida colonization, and its relationship to the quality of glycemic control (assessed by glycosylated hemoglobin) and other confounders, in type II diabetics who have periodontitis.

STUDY DESIGN

Candida species were isolated from the tongue and subgingival plaque of the 2 deepest periodontal pockets from 78 patients, and were identified by RapID Yeast Plus System. Student's t test, χ(2) test or Fisher's exact test, analysis of variance, multivariate logistic regression analysis, and Spearman's correlation test were used.

RESULTS

Candida species colonized 46 (59%) and 38 (48.7%) of the patients tongue and subgingival plaque, respectively. Subgingival Candida was more prevalent in females than males (P = .041). The quality of glycemic control correlated with the prevalence of subgingival Candida (P = .047) and the severity of gingival disease (P = .047).

CONCLUSION

Poor glycemic control and female gender may be associated with increased subgingival Candida in patients with type II diabetes.

The prevalence of oral Candida infections in periodontitis patients with type 2 diabetes mellitus

OBJECTIVES

The purpose of this study was to determine the prevalence of Candida spp. in periodontitis patients with type 2 diabetes mellitus.

METHODS

This cross-sectional study included 42 diabetic patients with periodontitis (aged 21-70 years; 18 males and 24 females). Clinical measurements included probing pocket depth (PPD), clinical attachment level (CAL) and hemoglobin A1c (HbA1c) levels. Sub-gingival samples were collected from the mesio-buccal aspect of 3 teeth for fungal analysis. Candida species, including Candida albicans, Candida dubliniensis, Candida tropicalis and Candida glabrata, were identified using Gram staining, the germ tube test, CHROMagar, Staib agar and API 20C AUX.

RESULTS

The overall prevalence of Candida in diabetic patients with periodontitis observed in our study was 52%. The most common spp. of Candida identified were C. albicans (38%), followed by C. dubliniensis (9.5%), C. tropicalis (4.7%) and C. glabrata (4.7%). Compared to females, male patients were characterized by increased levels of Candida infections. Our results also indicate that individuals over the age of 40 had increased levels of Candida infections compared to patients younger than 40. Candida infections were higher among subjects with elevated blood sugar levels (HbA1c>9) compared to individuals with well-controlled blood sugar levels (HbA1c<6). Patients with PPDs≥5 had an increased risk of Candida infection compared to patients with PPDs between 3 and 4.

CONCLUSION

This study indicates that the frequency of C. albicans is higher than the frequencies of C. dubliniensis, C. tropicalis and C. glabrata in diabetic patients with periodontitis. Candida infections were observed at increased frequencies among subjects with high blood sugar levels and PPDs≥5.

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.

Enrichment of multilocus sequence typing clade 1 with oral Candida albicans isolates in patients with untreated periodontitis

This study investigated the prevalence and cell density of Candida species in periodontal pockets, healthy subgingival sites, and oral rinse samples of patients with untreated periodontitis. Twenty-one periodontitis patients underwent sampling at two periodontitis sites, and 19/21 of these patients underwent sampling at one periodontally healthy site. Both paper point and curette sampling techniques were employed. The periodontitis patients and 50 healthy subjects were also sampled by oral rinse. Candida isolates were recovered on CHROMagar Candida medium, and representative isolates were identified. Candida spp. were recovered from 10/21 (46.7%) periodontitis patients and from 16/50 (32%) healthy subjects. C. albicans predominated in both groups and was recovered from all Candida-positive subjects. Candida-positive periodontitis patients yielded Candida from periodontal pockets with average densities of 3,528 and 3,910 CFU/sample from curette and paper point samples, respectively, and 1,536 CFU/ml from oral rinse samples. The majority (18/19) of the healthy sites sampled from periodontitis patients were Candida negative. The 16 Candida-positive healthy subjects yielded an average of 279 CFU/ml from oral rinse samples. C. albicans isolates were investigated by multilocus sequence typing (MLST) to determine if specific clonal groups were associated with periodontitis. MLST analysis of 31 C. albicans isolates from periodontitis patients yielded 19 sequence types (STs), 13 of which were novel. Eleven STs belonged to MLST clade 1. In contrast, 16 C. albicans isolates from separate healthy subjects belonged to 16 STs, with 4 isolates belonging to clade 1. The distributions of STs between both groups were significantly different (P = 0.04) and indicated an enrichment of C. albicans isolates in periodontal pockets, which warrants a larger study.

Periodontal conditions and prevalence of putative periodontopathogens and Candida spp. in insulin-dependent type 2 diabetic and non-diabetic patients with chronic periodontitis--a pilot study

OBJECTIVES

The aims of this study were to evaluate periodontal conditions and identify the presence of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Tannerella forsythia, and four different species of Candida (C. albicans, C. dubliniensis, C. glabrata and C. tropicalis) in periodontal pockets and furcation sites of insulin-dependent type 2 diabetic and non-diabetic patients with generalised chronic periodontitis.

DESIGN

Clinical parameters, including oral status assessed using plaque index, gingival index, probing depth, gingival recession and clinical attachment level and systemic conditions with fasting glucose level or glycosylated haemoglobin were measured in diabetic and non-diabetic patients with chronic periodontitis. Samples of subgingival biofilm were obtained from the periodontal pockets and furcation sites and submitted to phenol-chloroform DNA extraction and PCR analysis using specific primers.

RESULTS

Clinical conditions of diabetic and non-diabetic patients were similar, without statistical differences in both periodontal indexes and glucose levels (p>0.05). Diabetics had a higher prevalence of Candida spp., mainly C. albicans and C. dubliniensis, and a lower frequency of T. forsythia, when compared to non-diabetic patients, for both periodontal sites. C. glabrata and C. tropicalis were not found in periodontal pockets and furcation sites of non-diabetic patients.

CONCLUSION

The results demonstrated a strong colonisation of Candida spp. in the periodontal sites of diabetic patients that have generalised chronic periodontitis with a higher prevalence of C. dubliniensis followed by C. albicans.

Interspecies pheromone signaling promotes biofilm formation and same-sex mating in Candida albicans

The opportunistic pathogen Candida albicans undergoes a parasexual mating cycle in which cells must switch from the conventional "white" form to the alternative "opaque" form to become mating competent. Pheromones secreted by opaque cells induce the formation of polarized mating projections and result in cell-cell conjugation. In contrast, white cells are unable to undergo mating, but can still respond to pheromone by expression of adhesion genes that promote biofilm formation. In this study, we have analyzed the dual ability of pheromones to activate mating by opaque cells and biofilm formation by white cells. We first show that there is considerable plasticity in interactions between the α pheromone and its receptor, Ste2, by analysis of analogs of the α pheromone. Significantly, substituted forms of α pheromone can induce a response in opaque cells and this is sufficient to drive same-sex a-a cell fusion and homothallic mating. In addition, pheromone analogs were able to induce adhesion and biofilm formation in white cells of C. albicans. Because of the observed plasticity in pheromone signaling, we subsequently tested putative pheromones from multiple Candida species and identified nonnative ligands that can induce self-mating and biofilm responses in C. albicans. Our findings demonstrate that environmental signals can initiate C. albicans parasexual reproduction and biofilm formation, and highlight the role of the pheromone-signaling apparatus in mediating these functions.