Genotyping and antifungal susceptibility of human subgingival Candida albicans isolates

Prevalence of Candida albicans in primary endodontic infections associated with a higher frequency of apical periodontitis in type two diabetes mellitus patients

To identify the prevalence of C. albicans in primary endodontic infections of type two diabetes mellitus (T2DM) patients and compare their clinical and radiographical characteristics with a non-diabetic control group, establishing the possible relationship between primary endodontic infection, T2DM, and C. albicans, since diabetes mellitus (DM), influences the development, course, and response to the treatment of apical periodontitis, but the presence of Candida albicans (C. albicans) has not been considered before. A total of 120 patients were selected and divided into two groups: 60 T2DM diagnosed patients and 60 non-diabetic controls. A clinical examination and radiographic analysis were performed to establish a periapical index score (PAI). Root canal samples were taken. Deoxyribonucleic acid (DNA) was extracted, and specific primers were used to identify C. albicans by polymerase chain reaction (PCR). A twofold increase in the prevalence of C. albicans in T2DM patients was observed in contrast to control patients (p = 0.0251). Sixty-five percent of T2DM patients with positive C. albicans scored a ≥ 3 PAI, while only 27% of the patients without C. albicans had a ≥ 3 PAI score (p = 0.0065). Long-term DM patients presented C. albicans more frequently (p < 0.0001). In this study, long-term T2DM patients carried C. albicans in their root canals more frequently when having a primary endodontic infection. Furthermore, this C. albicans presence seems to be related to a higher frequency of apical periodontitis.

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.

Candida species biotypes in the oral cavity of infants and children with orofacial clefts under surgical rehabilitation

Patients with orofacial clefts present various risk factors for oral infectious diseases, resulting from anatomical and physiological changes and those resulting from rehabilitating therapeutic interventions. The incidence of Candida species in groups of babies and children with orofacial clefts, during pre- and post-operative periods and until return to first consultation, and the profiles for antifungal sensitivity and virulence in vitro were investigated. Oral samples were collected at different times over the surgical procedures and post-surgical clinical consultation and seeded in chromogenic culture media CHROMagar Candida^®. Candida biotypes were identified by accessing species-specific genomic DNA sequences by PCR techniques and electrophoretic procedures. Antifungal susceptibility testing was performed by the method of microdilution in broth using the antifungals amphotericin B (AP), nystatin (NYS) and fluconazole (FLC). SAP and PL exoenzyme activities were determined by classical microbiological methods. Some orofacial clefts occurred preferentially in male or female. Low incidence (39.1%) of oral colonization by Candida species (C. albicans, C. krusei, C. tropicalis and Candida spp.) was reported in patient admission to surgical ward, with no correlation to orofacial cleft types or surgical history. Significant reduction in frequencies of Candida and changes of species, over sampling periods, showed dynamic patterns of oral colonization: elimination, maintenance or neocolonization of the biotypes. These biotypes showed sensitivity to AP (100%), partial resistance to FLC (<10%) and variable MICs for NYS (0.125-4 μg/mL), in addition to strong exoenzyme activities, especially for SAP. Clinical and therapeutic conducts for surgical rehabilitation, anatomical and physiological characteristics of patients with orofacial clefts, and cultural behavior and regionalism of the patient population served could influence the frequencies and dynamics of oral colonization by Candida species. The data showed Candida biotypes resistant to FLC and sensitive (AP) or clinically compatible (NYS) to polyenes, especially C. albicans, in the oral cavity of patients predisposed to oral colonization and candidiases, contributing to clinical conducts in possible antifungal therapies. These biotypes were considered potentially virulent and able to partially modulate their virulence factors, especially SAP, under the conditions favored by host.

Oral Candida colonization in patients with chronic periodontitis. Is there any relationship?

BACKGROUND

Candida can be implicated in the pathology of chronic periodontitis.

AIMS

To analyze the oral Candida carriage in patients suffering from chronic periodontitis (CP) and its correlation with the severity of this condition.

METHODS

Microbiological samples were taken from 155 patients using the oral rinse (OR) technique and by using paper points in the periodontal pockets (GPP). These patients were divided into 3 groups: 89 patients without CP (control), 47 with moderate CP, and 19 with severe CP. Samples were cultured in a Candida chromogenic agar for Candida. Species were identified by microbiological and molecular methods.

RESULTS

Candida was isolated in the OR of 45 (50.6%), 21 (44.7%), and 11 (57.9%) patients, respectively, and in the GPP of 32 (36%), 14 (29.2%), and 10 (42.6%) patients from the control, moderate CP and severe CP groups, respectively. Candida was isolated more frequently and in a greater burden in OR than in GPP (p<0.01). Candida albicans was the most prevalent species. GPP of patients with CP had poor fungal biodiversity (p<0.01).

CONCLUSIONS

Colonization by Candida was present in the samples of patients without CP, and with both moderate and severe CP. Nonetheless, patients with severe CP had a higher rate of Candida colonization, especially by C. albicans.

Antifungal activity of propolis against Candida species isolated from cases of chronic periodontitis

This research evaluated the fungistatic and fungicidal activities of red propolis alcoholic extract (RPAE) against different Candida species isolated from chronic periodontitis cases, and compared with chlorhexidine (CHX). Nineteen samples of Candida species (C. albicans [n = 12], C. tropicalis [n = 5] and C. glabrata [n = 2]) isolated from chronic periodontitis cases were analyzed. The fungistatic and fungicidal activity of both RPAE and CHX were evaluated using fluconazole and C. parapsilosis (ATCC 6258) as a control. Fungistatic activity was analyzed based on the Clinical and Laboratory Standards Institute (CLSI) reference procedure to determine the minimum inhibitory concentrations. Fungicidal activity was established according to the absence of fungal growth on Sabouraud Dextrose Agar medium. The fungistatic and fungicidal activities of RPAE were observed, respectively, at 32-64 μg/mL and 64-512 μg/mL for C. albicans, 64 μg/mL and 64-256 μg/mL for C. glabrata, and 32-64 μg/mL and 64 µg/mL for C. tropicalis. CHX fungistatic activity was observed at concentrations of 0.003-1.92 µg/mL for C. albicans, 1.92 µg/mL for C. glabrata, and 0.03-1.92 µg/mL for C. tropicalis. Fluconazole fungistatic activity ranged between 1-64 μg/mL, and fungicidal activity occurred at 8-64 μg/mL, for the three Candida species analyzed. All the Candida species were susceptible to RPAE antifungal activity, but five samples of C. albicans, one of C. tropicalis and one of C. glabrata were resistant to fluconazole antifungal activity. CHX showed fungistatic activity against all the Candida species analyzed. The antifungal potential of these substances suggests that they can be applied as an alternative treatment for diseases affected by these species.

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.

Assessment of dentifrices against Candida biofilm

The invasion of opportunistic pleiomorphic Candida albicans into oral cavity environment leads to development and progression of its resistance to both naturally occurring antifungal peptides in human saliva as well as commercially available antifungal therapies. As a result of this, the usage and popularity of natural medicine and dentifrices had increased significantly in the last decade. In the present investigation, we have assessed the action of locally available dentifrices against C. albicans biofilm. Disk diffusion test showed maximum zone of inhibition (20 mm) by herbal dentifrice (D-5) as compared to other dentifrices when incubated at 37 °C and 48 h. Assessment of dentifrice D-5 for its effectiveness against C. albicans was further shown in MIC(90) (3.12 mg mL(-1)) and SMIC(90) (6.2 mg mL(-1)) values for planktonic and sessile cells (biofilm forming), respectively. Our data depicted 80% reduction in the cell surface hydrophobicity when 6.2 mg mL(-1) of herbal dentifrice D-5 was used against 48-h grown Candida biofilm at 37 °C. Visualization of herbal dentifrice D-5-treated C. albicans biofilm under SEM revealed drastic reduction in the dense network of yeast, hyphae, and pseudohyphae enclosed in its ECM as compared to its control biofilm. The data were further supported by CLSM analysis which depicted C. albicans architecture disruption by herbal dentifrices. From the above data, it is inferred that these studies would provide researchers and medical practitioners with better insight into the antifungal effect of natural herbal dentifrices.

Genetic and phenotypic evaluation of Candida albicans strains isolated from subgingival biofilm of diabetic patients with chronic periodontitis

Candida spp. are commensal microorganisms that are part of the microflora of different sites within the oral cavity. In healthy subjects, who have an unaltered immunological status, these yeasts do not cause disease. However, in immunosuppressed individuals whose condition may have been caused by diabetes mellitus, Candida spp. can express different virulence factors and may consequently become pathogenic. Studies have detected the presence of Candida spp. in periodontal sites of patients with chronic periodontitis, especially those that are immunologically compromised. However, the role of these microorganisms in the pathogenesis of periodontal disease is still unknown. The objectives of this study were: (1) to isolate and identify Candida albicans strains from subgingival sites of diabetic patients with chronic periodontitis; (2) to evaluate the following virulence factors; colony morphology, proteinase, phospholipase and hemolysin activities and cell surface hydrophobicity (CSH) under different atmospheric conditions; and (3) to determine the genetic patterns of these C. albicans isolates. Microbial samples were collected from subgingival sites and seeded on CHROMagar for subsequent identification of C. albicans by polymerase chain reaction (PCR). For the phenotypic tests, all strains of C. albicans were grown under reduced oxygen (RO) and anaerobiosis (ANA) conditions. Genotypes were defined by the identification through PCR of the transposable introns in the 25S rDNA. The results obtained relative to virulence factors were analyzed according to the atmospheric condition or genetic group, using Chi-square and Wilcoxon non-parametric tests. In this study, 128 strains were identified as C. albicans and of these, 51.6% were genotype B, 48.4% were genotype A and Genotype C was not found. Most of the strains were alpha-hemolytic in both atmospheric conditions, without a statistical difference. However, when comparing the genotypes, 46.1% of the genotype A strains were beta-hemolytic. In relation to colony morphology, 100% of the strains under ANA showed rough colonies, which were especially prevalent in genotype A isolates. In contrast, most of the colonies were smooth under RO. C. albicans strains did not produce proteinase and phospholipase activity in the total absence of oxygen. In RO, most strains had high proteinase activity and were positive by phospholipase tests (P < 0.05). Hydrophobicity was higher in anaerobiosis and was noted mainly for genotype A isolates. In conclusion, environmental oxygen concentration influenced the virulence factors of C. albicans strains isolated from subgingival sites of diabetic and periodontal patients. In addition, genotype A seems to be more virulent based on the phenotypic tests evaluated in this study.

Candida spp. in periodontal disease: a brief review

Although the main reservoir of Candida spp. is believed to be the buccal mucosa, these microorganisms can coaggregate with bacteria in subgingival biofilm and adhere to epithelial cells. Such interactions are associated with the capacity of Candida spp. to invade gingival conjunctive tissue, and may be important in the microbial colonization that contributes to progression of oral alterations caused by diabetes mellitus, some medications, and immunosuppressive diseases such as AIDS. In addition, immune deficiency can result in proliferation of Candida spp. and germination of forms that are more virulent and have a higher capacity to adhere to and penetrate cells in host tissues. The virulence factors of Candida spp. increase host susceptibility to proliferation of these microorganisms and are likely to be important in the study of periodontal disease. Herein, we briefly review the literature pertaining to the role of Candida spp. in periodontal disease, and consider the main virulence factors, the host immune response to these microorganisms, and the effect of concomitant immunosuppressive conditions.

Genetic relatedness of subgingival and buccal Candida dubliniensis isolates in immunocompetent subjects assessed by RAPD-PCR

Background

It is recognized that Candida dubliniensis commonly colonizes oral and subgingival sites in immunocompetent subjects with periodontal disease.

Objective

Since there are few data available on genetic characterization of C. dubliniensis in periodontal pockets and other oral sites, the aim of this study was to characterize subgingival and mucosal C. dubliniensis isolates recovered from immunocompetent subjects and to assay the genetic similarity of such isolates from both niches in the same patient by random amplified polymorphic DNA (RAPD).

Design

C. dubliniensis recovered from subgingival plaque and from buccal cavity samples were studied in 240 immunocompetent non-smoking individuals. Arbitrary amplification was carried out by RAPD-polymerase chain reaction (PCR).

Results

RAPD analysis showed identical genotypes of C. dubliniensis in different sampling sites (buccal cavity and subgingival areas) in eight of 10 patients except for those derived from two participants who presented presumably unrelated isolates.

Conclusions

On the basis of the findings presented, the origin of the colonization of C. dubliniensis in subgingival biofilm seems to be the buccal cavity in a single patient. Consequently, it may be assumed that most of C. dubliniensis in these sites arise from the endogenous commensal strains.

Genetic diversity and exoenzyme activities of Candida albicans and Candida dubliniensis isolated from the oral cavity of Brazilian periodontal patients

OBJECTIVE

Mucosal surfaces are the primary oral reservoirs of Candida species, but these species can also be found in subgingival biofilm. The present study investigated the genetic diversity and production of exoenzymes of C. albicans and C. dubliniensis isolated from the oral cavity of systemically healthy patients with periodontitis.

DESIGN

Fifty-three patients were analysed. Samples were collected from three oral cavity sites (periodontal pocket, gingival sulci and oral mucosa), plated and, after isolation, suspect strains of C. albicans and C. dubliniensis were identified by PCR. The genetic diversity of the isolates was evaluated by RAPD and the activities of the secreted aspartyl proteinases and phospholipases were evaluated by the agar plate method.

RESULTS

Twenty-one patients showed positive results for Candida spp. There were no statistically significant differences between genders, or between sites. C. albicans was the most frequently found specie, while C. dubliniensis was isolated from the periodontal pocket of only one patient. Sixteen genotypes were detected among the C. albicans isolates, and one among the C. dubliniensis isolates. The similarity coefficient (S(SM)) values among the C. albicans genotypes ranged from 0.684 to 1.0 with an average of 0.905+/-0.074. All isolates produced high levels of Saps and most of them produced high levels of phospholipases. No relationship was found between the genotypes and the pattern of enzymatic production. There was no association between specific genotypes and their site of isolation.

CONCLUSIONS

The results of the present study suggest that genetically homogeneous strains of C. albicans are present in the oral cavity of patients with periodontitis and that these strains are capable of producing high levels of exoenzyme.

Genotypic relatedness of yeasts in thrush and denture stomatitis

BACKGROUND/AIM

Candida is an opportunistic pathogen. Understanding its genetic characters might increase our understanding of the pathogenesis of candidosis. We examined the genetic relationships of yeasts from the most common forms of oral candidosis: thrush and denture stomatitis.

METHODS

Yeasts were sampled from palate, buccal mucosa, gingival sulci/periodontal pockets and/or denture fitting surface of 19 thrush patients and 22 denture stomatitis patients. Random amplified polymorphic DNA and the Dendron computer-assisted program were used to determine the genotypic relatedness of the yeasts.

RESULTS

A dendrogram generated from 105 thrush isolates had similarity coefficients (S(AB)) ranging from 0.58 to 1 with four clusters derived at S(AB) 68%. Another dendrogram was generated from 91 isolates from denture stomatitis, with S(AB) ranging from 0.59 to 1. Three clusters were established at S(AB) 71%. In a composite dendrogram incorporating the thrush and denture stomatitis data and orally healthy data compiled from a previous study, five genotypic clusters were generated at S(AB) 68%. Cluster II, the most dominant, comprised isolates from thrush, denture stomatitis and healthy conditions, while clusters III and IV contained yeasts mainly from thrush.

CONCLUSIONS

Palatal yeast carriage was significantly increased in thrush and denture stomatitis, also after radiation, chemotherapy and denture wearing. The buccal mucosa was favorable for yeast colonization regardless of oral condition. Yeasts in thrush were more diverse than in conditions of oral health. The common clone (II) of infecting yeasts and commensals suggested that commensals could induce thrush and denture stomatitis, whereas the unique clones in thrush (III, IV) might have been established through strain replacement or maintenance with minor genetic variation.

Genetic relatedness of oral yeasts within and between patients with marginal periodontitis and subjects with oral health

BACKGROUND

Yeasts are found in periodontal pockets at a frequency of 15-21%. However, the genetic relatedness of oral yeasts within and between patients with marginal periodontitis is not clear.

OBJECTIVES

Assay genetic relatedness of oral yeasts from marginal periodontitis patients and oral health subjects, as well as genetic relatedness of yeasts from different oral sites in these two groups of participants.

MATERIAL AND METHODS

Yeast isolates were collected from 23 marginal periodontitis patients and 19 oral health subjects. Random amplified polymorphic DNA (RAPD) fingerprinting and the Dendron computer-assisted program for gel analyses were applied for estimation of genetic relatedness of yeasts.

RESULTS

The similarity coefficient (S(AB)) of the marginal periodontitis group ranged from 0.49 to 1.00 with an average of 0.64 +/- 0.11, whereas the S(AB) of the oral health group ranged from 0.62 to 1.00 with an average of 0.72 +/- 0.07. Three genetic clusters and 73 genotypes were obtained from the marginal periodontitis group, whereas three genetic clusters and 55 genotypes were found in the oral health group. In the pooled dendrogram, 57% of the yeast isolates and the type strain of Candida albicans fell in a major cluster V. There were no significant differences between the frequencies of clusters from the different oral sites within the two participant groups.

CONCLUSIONS

Genetically heterogeneous yeasts were found in the oral cavities of marginal periodontitis patients and oral health subjects. Similar genetic clustering patterns were obtained from the yeasts of the two groups, with cluster V being most predominant. Yeasts of the marginal periodontitis group were more genetically diverse than yeasts of the oral health group, and some yeasts of the marginal periodontitis group exhibited unique genetic patterns. There was no clear association between yeast genetic clusters and oral sites in the two participant groups.

The effect of calcium chelating or binding agents on Candida albicans

OBJECTIVE

The aim of this study was to evaluate antifungal effects of calcium-chelating or -binding agents on Candida albicans comparing with conventional antifungal agents.

STUDY DESIGN

Two clinical oral isolates and 1 standard strain of C albicans were included in the study. Test solutions were ethylenediamine-tetraacetic acid (EDTA), ethyleneglycol-tetraacetic acid (EGTA), sodium fluoride (NaF), titanium tetrafluoride (TiF4), nystatin, and ketoconazole. Minimum inhibitory and fungicidal concentrations of the solutions were determined. The results were analyzed statistically using Friedman's nonparametric 2-way ANOVA and Mann-Whitney U tests.

RESULTS

All isolates demonstrated similar susceptibility patterns (P>.05). Except ketoconazole, EDTA had the highest antifungal and fungicidal activity, followed by TiF4. EGTA and NaF were the weakest agents against C albicans among all test solutions.

CONCLUSION

EDTA and TiF4 may be recommended as an alternative irrigating solution particularly in persistent root canal infections and in root canals of patients having a high incidence of oral candidosis.

Clade-related amphotericin B resistance among South African Candida albicans isolates

Molecular epidemiology revealed 5 distinct clades among clinical isolates of Candida albicans, using DNA fingerprinting with the complex Ca3 probe. Certain clades were found to be highly enriched in particular geographical areas (e.g., clade E in Europe and clade SA in South Africa, whereas clade II is completely absent in the southwest United States). From fingerprinting data, it is concluded that little interclade recombination takes place, and therefore, it would not be unusual to expect clade-specific phenotypic characteristics. The first clade-related phenotypic difference was found with 5-flucytosine resistance being almost exclusively restricted to clade I. When in vitro antifungal susceptibility testing revealed 8.4% of South African oral yeast isolates to be naturally resistant to amphotericin B, it was decided to investigate a possible clade relationship for this relatively high resistance. Thirty-eight amphotericin B-resistant C. albicans isolates were fingerprinted, and a mixed dendrogram was constructed, including previously fingerprinted isolates of known clade affiliation. With the exception of clade III, resistant isolates occurred in all clades (clade I=3; clade II=3; clade NG=3; and clade SA=29), except clade III. However, the higher number of resistant isolates that clustered in clade SA was statistically significant (P<or=0.02, chi2=11.32).