Association of oral yeast carriage with specific host factors and altered mouth sensation

A Membrane-Targeted Photosensitizer Prevents Drug Resistance and Induces Immune Response in Treating Candidiasis

Candida albicans (C. albicans), a ubiquitous polymorphic fungus in humans, causes different types of candidiasis, including oral candidiasis (OC) and vulvovaginal candidiasis (VVC), which are physically and mentally concerning and financially costly. Thus, developing alternative antifungals that prevent drug resistance and induce immunity to eliminate Candida biofilms is crucial. Herein, a novel membrane-targeted aggregation-induced emission (AIE) photosensitizer (PS), TBTCP-QY, is developed for highly efficient photodynamic therapy (PDT) of candidiasis. TBTCP-QY has a high molar absorption coefficient and an excellent ability to generate 1 O2 and •OH, entering the interior of biofilms due to its high permeability. Furthermore, TBTCP-QY can efficiently inhibit biofilm formation by suppressing the expression of genes related to the adhesion (ALS3, EAP1, and HWP1), invasion (SAP1 and SAP2), and drug resistance (MDR1) of C. albicans, which is also advantageous for eliminating potential fungal resistance to treat clinical infectious diseases. TBTCP-QY-mediated PDT efficiently targets OC and VVC in vivo in a mouse model, induces immune response, relieves inflammation, and accelerates the healing of mucosal defects to combat infections caused by clinically isolated fluconazole-resistant strains. Moreover, TBTCP-QY demonstrates excellent biocompatibility, suggesting its potential applications in the clinical treatment of OC and VVC.

Medium-chain fatty acids as an alternative treatment for denture stomatitis in older people

OBJECTIVE

To determine the effect of medium-chain fatty acids (MCFA) on the severity of denture stomatitis (DS) and the counts of Candida spp. in older people (OP) wearing removable prostheses (RP).

MATERIALS AND METHODS

This randomized, controlled and triple-blind study included forty-three OP presenting DS. The control group was treated with 0.12% chlorhexidine (CHX) and the experimental group with MCFA, 2 × /day for 15 days. Intraoral examination and counts of Candida spp. were performed at 0, 7, and 15 days. The differences between both groups in the decrease of the severity of DS and the viability of Candida spp. were determined clinically and microbiologically, respectively.

RESULTS

OP carriers of RP treated with MCFA presented remission of the clinical signs of DS, but the Candida spp. counts only decreased significantly in the CHX-treated group at 7 days of treatment (p < 0.05). Besides, MCFA was shown to reduce the clinical signs of DS after the first week of application, while CHX after the second week.

CONCLUSIONS

The MCFA is effective in reducing the clinical signs of DS associated with oral candidiasis in subjects with RP. Both treatments showed a significant decrease in severity, for MCFA after the first week and for CHX two weeks after starting the corresponding treatment.

CLINICAL RELEVANCE

The MCFA is an effective, harmless, and accessible treatment alternative against DS, since it manages to reduce the severity of the lesion in the milder cases of DS in the oral mucosa of OP carriers of RP.

Efficacy of oral nystatin treatment for patients with oral mucosal dysesthesia but without objective oral mucosal manifestations and necessity of Candida culture test before oral nystatin treatment

Background/purpose

Materials and methods

Results

Conclusion

Factors influencing the presence of Candida dubliniensis and other non-albicans species in patients with oral lichen planus: a retrospective observational study

Objectives

The epidemiologic distribution of non-albicans species in the oral cavity of oral lichen planus (OLP) patients remains uncertain. Therefore, the aim of this study was to identify factors associated with the presence of C. dubliniensis and other non-albicans species. Furthermore, independent risk factors for Candida superinfection in OLP should be identified.

Material and methods

Epidemiologic data and microbiological findings from 268 symptomatic OLP patients who underwent continuous oral swab culture over a 5-year period (2015–2019) were retrospectively reviewed. Candida species identification and semi-quantification were obtained by culture on CHROMagar Candida, followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).

Results

C. albicans was the most frequently isolated species (72.3%), followed by C. glabrata (7.3%), C. dubliniensis (5.8%), C. krusei and C. parapsilosis (both 2.6%). The presence of C. dubliniensis was significantly associated with tobacco smoking. Other non-albicans spp. were significantly more often detected in patients using removable dentures. Increasing age and the intake of psychotropic drugs were identified as independent risk factors of Candida superinfection in OLP.

Conclusion

In OLP patients, certain local and systemic factors increase the risk of carrying potentially drug-resistant Candida species and the development of Candida superinfection of OLP lesions.

Clinical relevance

Due to the frequent detection of non-albicans species in OLP, resistance or at least reduced sensitivity to azole antifungals should be expected, especially in smokers and patients using removable dentures. In the case of oral complaints, a superinfection with Candida should be considered, whereby older patients and patients taking psychotropic drugs have an increased risk for oral infection with Candida.

Risk factors related to oral candidiasis in patients with primary Sjögren's syndrome

BACKGROUND

Candidiasis is the most frequent mycotic infection of the oral cavity. The aim of this study was to investigate the presence of clinical oral candidiasis and Candida albicans yeast in a population diagnosed of primary Sjögren's syndrome (pSS) and to study the possible factors associated with this infection.

MATERIAL AND METHODS

An observational cross-sectional study was conducted in 61 pSS patients (60 women, 1 man, mean age 57.64±13.52) where patient based information (demographic and medical, tobacco and alcohol consumption history), intraoral parameters (presence of dentures, clinical signs of candidiasis), salivary analytical information (number of Candida albicans as colony-forming units per millilitre (CFU/mL), salivary pH levels, unstimulated whole saliva (UWS) and stimulated whole saliva (SWS) were collected.

RESULTS

13.1% of pSS patients presented oral signs of candidiasis. Denture stomatitis and angular cheilitis were the most common lesions. 87.5% of patients with clinical candidiasis presented reduced pH levels and salivary flow in both UWS and SWS. A significant statistical negative correlation was found between CFU/mL of Candida albicans and levels of UWS and SWS. A negative correlation was found between pH levels and CFU/mL, although not statistically significant.

CONCLUSIONS

A reduced salivary flow may predispose pSS patients to Candida albicans overgrowth, which may show with clinical signs. Preventive measures are of great importance to avoid and to treat this condition promptly.

Oral candidal carriage correlates with CD4+ cell count but not with HIV and highly active antiretroviral therapy status

AIM

The occurrence of oropharyngeal candidiasis (OPC) may be influenced by oral candidal carriage (OCC). Although OPC is strongly associated with low CD4⁺ cell count (400-700 cells/mm³ ) and a lack of highly active antiretroviral therapy (HAART), the effect of these two parameters on OCC is debatable. We investigated the oral candidal carriage, species diversity, antifungal susceptibility and the association of OCC with CD4⁺ cell count and HAART.

METHODS

Oral candidal isolates from 120 HIV⁺ patients (60 receiving and 60 not receiving HAART) and 60 healthy controls were quantified, and their species determined using standard culture and biochemical methods, followed by antifungal susceptibility testing using the agar dilution method.

RESULTS

The OCC was significantly higher in HIV⁺ patients; Candida albicans was the most frequently isolated species in both groups, followed by Candida tropicalis. Candidal density carriage correlated significantly with CD4⁺ cell count, but not with HIV and HAART status. Among the isolates from HIV⁺ patients, 35.4% showed reduced susceptibility to fluconazole.

CONCLUSION

HIV status results in significantly elevated rates of OCC C albicans remains the predominant pathogen, although other species are emerging rapidly. Resistance to fluconazole is on the rise, and more efficient treatment strategies need to be implemented.

Phenotypic and genotypic evaluation of adherence and biofilm development in Candida albicans respiratory tract isolates from hospitalized patients

In recent years, a significant number of epidemiological variations have been observed for fungal infections. In immunocompromised patients, Candida albicans is crucially involved in invasive infections, mostly originating in respiratory tract colonization. The global rise in candidiasis has led researchers to investigate possible correlations between fungal strains virulence profiles and their pathogenic potential, among the most investigated genes being those involved in adherence and biofilm development. In this study, we established the adherence gene profiles of C. albicans strains isolated from respiratory tract secretions in patients hospitalized for cardiovascular diseases and correlated them with the ability of the respective strains to colonize the epithelial cells and form biofilms on the inert substratum. The strains isolated from the lower respiratory tract exhibited the highest adherence capacity and were intensive biofilm producers. The SAP9, ALS3, ALS5, and ALS6 genes were the most frequently detected. There was a significant association between the presence of ALS 3 gene and the cellular substrate colonizing potential of the harboring strains. We also found that the strains expressing SAP9 were more virulent in the phenotypic assays. Detecting the presence of adherence genes from different clinical isolates is a cost-effective tool that would allow researchers to predict the virulence of a certain strain and estimate its potential to adhere to host cells and develop biofilms.

Diagnosis and management of oral candidosis

Candida is a fungus (yeast) that is generally regarded as a normal and harmless member of the oral microbiome in humans. Should host defences against these commensals be compromised in any way then Candida can cause clinical signs and symptoms, which manifest as distinct forms of oral candidosis (candidiasis). Candida albicans is the most frequently isolated candidal species from the oral cavity, although a range of non-C. albicans Candida species are being increasingly encountered. The basic principle of the management of candidosis is to identify and eliminate any underlying host predisposing factor. However, in many cases, antifungal therapy will also be required as part of initial management. This article will provide an overview of the isolation, identification and pathogenicity of Candida species encountered within the mouth and relate these to clinical management of oral candidosis.

Prevalence of Candida albicans and non-albicans on the tongue dorsa of elderly people living in a post-disaster area: a cross-sectional survey

Background

Candida species are normal commensal organisms of the mouth. However, they can cause oral mucosal and severe systemic infections in persons with reduced immune function, which is common in the very elderly. In post-disaster areas, the number of elderly residents rapidly increases due to the outflow of younger generations. Hence, we examined the prevalence of Candida albicans and non-albicans in association with oral and systemic conditions, life style, medications, and living conditions.

Methods

This study was performed in 2014. Participants of this study were 266 community dwellers aged 60 years or older in Otsuchi town, which was severely damaged by the Great East Japan Earthquake and Tsunami in 2011. Oral specimens were collected from tongue dorsa by swabbing. After 48 h incubation on CHROMagar™ medium, C. albicans and non-albicans were identified by the morphology and pigmentation of the colonies. Oral and systemic health check-ups were performed to assess the following: number of remaining teeth and periodontal status, oral hygiene, use of dentures, obesity, hypertension, hyperlipidemia, and hyperglycemia. A questionnaire addressed lifestyle, medications, and living conditions. Using the variables above, the relative factors involved in the colonization and the amounts of each type of Candida were determined.

Results

C. albicans and non-albicans were detected in 142 (53.4%) and 63 (23.7%) participants, respectively. Multinomial logistic regression analyses revealed that the significant factors of colonization by C. albicans were “having decayed teeth” and “relocation from home”. Factors related to non-albicans colonization were “age over 80 years”, “number of remaining teeth”, “use of dentures”, and “obesity”. On the contrary, none of the parameters were related to the amount of non-albicans in the carrier, and the amount of C. albicans was significantly associated with “number of teeth” and “hypertension”.

Conclusions

Prevalence-related factors differed between C. albicans and non-albicans colonization. In addition, other than oral status, systemic and living conditions affected the prevalence of both C. albicans and non-albicans in elderly people living in a post-disaster area.

Electronic supplementary material

The online version of this article (doi:10.1186/s12903-017-0342-0) contains supplementary material, which is available to authorized users.

Mining the oral mycobiome: Methods, components, and meaning

Research on oral fungi has centered on Candida. However, recent internal transcribed spacer (ITS)-based studies revealed a vast number of fungal taxa as potential oral residents. We review DNA-based studies of the oral mycobiome and contrast them with cultivation-based surveys, showing that most genera encountered by cultivation have also been detected molecularly. Some taxa such as Malassezia, however, appear in high prevalence and abundance in molecular studies but have not been cultivated. Important technical and bioinformatic challenges to ITS-based oral mycobiome studies are discussed. These include optimization of sample lysis, variability in length of ITS amplicons, high intra-species ITS sequence variability, high inter-species variability in ITS copy number and challenges in nomenclature and maintenance of curated reference databases. Molecular surveys are powerful first steps to characterize the oral mycobiome but further research is needed to unravel which fungi detected by DNA are true oral residents and what role they play in oral homeostasis.

A comparative study of oral candidal species carriage in patients with type1 and type2 diabetes mellitus

Context:

Diabetes mellitus can have profound effects upon the oral tissues especially in patients with poor glycemic control being prone to severe and/or recurrent infections particularly candidiasis. The main aim was to study the association between Type 1 and Type 2 diabetes mellitus and candidal carriage.

Materials and Methods:

The study design comprised of previously diagnosed 30 patients each with type 1 diabetes mellitus (Group A) and type 2 diabetes mellitus (Group B) and 30 age-, sex- and dental status-matched healthy non-diabetic individuals as controls (Group C). The saliva samples were collected and inoculated onto Sabouraud dextrose agar (SDA) and chromogenic agar culture medium. Candidal colony forming units per ml (CFU/ml) values were determined.

Statistical Analysis:

Data were analyzed by χ² test, Mann-Whitney U-test, Spearman's rank correlation and Karl Pearson's correlation coefficient.

Results:

Data analysis showed statistically significant higher positive candidal growth in Group A and Group B when compared to Group C. The CFU/ml values were significantly higher in Groups A and B as compared with Group C. Significant positive correlation of CFU/ml with fasting blood sugar level and HbA1c% in both Groups A and B was seen. Oral signs and symptoms observed in diabetics were dry mouth, burning sensation, fissuring and atrophic changes of tongue and erythematous areas, which positively correlated with candidal load.

Conclusion:

The glycemic control status of the diabetic patients may directly influence candidal colonization. The quantitative and biochemical characterization allows better insight into the study of association of diabetes mellitus and candida.

Effects of surface roughness and dimorphism on the adhesion of Candida albicans to the surface of resins: scanning electron microscope analyses of mode and number of adhesions

AIM

Candida albicans is a common oral fungus but can cause serious conditions such as Candida stomatitis. We investigated C. albicans adhesion to the surface of denture-base resins at two growth phases.

METHODS

Fungal suspensions of logarithmic (9 h) and stationary phase (24 h) C. albicans (JCM2085) were used. Scanning electron microscopy (SEM) confirmed that yeast and mycelial forms were predominant in 9-h and 24-h cultures, respectively. Resin strips were polished to three surface roughness levels (Ra 3.2 μm, Ra 0.48 μm and Ra 0.06 μm) and were then immersed in C. albicans suspensions for both phases. The SEM images were taken at five sites on each strip.

RESULTS

Adhesion of mycelial-form C. albicans on rough surfaces (Ra = 3.2) was 2.2 times higher than on smooth surfaces (Ra = 0.06; 7030 vs 3580 adhesions/mm(2), P < 0.01). The hyphae of these mycelial forms fully penetrated the surface cracks. Fewer adhesions occurred for yeast-form C. albicans, regardless of surface type (440-620 adhesions/mm(2), P = n.s.).

CONCLUSION

Adhesion of yeast-form C. albicans was indifferent to surface roughness. In contrast, mycelial adhesion increased with surface roughness of the resin because mycelia infiltrated the minute protuberances on rough surfaces.

Oral Candida carriage, quantification, and species characterization in oral submucous fibrosis patients and healthy individuals

AIM

  To determine the prevalence of oral Candida carriage, candidal quantification, and various subtypes of Candida species in oral submucous fibrosis patients and healthy individuals.

METHODS

  The study comprised 30 clinically-diagnosed and -staged oral submucous fibrosis patients aged 20-40 years, and 20 age- and sex-matched controls. Buccal mucosa was sampled by sterile swab technique. Each sample was inoculated on Sabouraud's dextrose agar and CHROMagar culture media. Candida species identification was done using the KB006 Candida identification kit.

RESULTS

  Eleven (36.67%) cases in the study group, and two (10%) cases in the control group, yielded Candida on culture. The value of CFU/mL increased with an increased duration of betel quid chewing habit. All Candida-positive oral submucous fibrosis patients complained of a burning sensation. Candida albicans and Candida tropicalis were the most common species in the oral submucous fibrosis cases. Candida dubliniensis was isolated in both the study and control groups.

CONCLUSIONS

  Our observations in this study affirm that oral submucous fibrosis favors the colonization of Candida. Mucosal alterations due to the underlying disease process or betel quid chewing, coupled with other factors, might lead to candidal colonization, even in the absence of clinically-related mycotic manifestations.

The relationship between oral hygiene and oral colonization with Candida species in healthy adult subjects*

Poor oral hygiene has been frequently suggested as a predisposing factor for oral candidal colonization, but the convincing evidence is lacking.

OBJECTIVE

To assess and compare oral candidal colonization, both quantitatively and qualitatively, in groups of healthy dentate subjects with different levels of oral hygiene as determined by the plaque index (PI) and gingival index (GI) scores.

METHODS

The concentrated oral rinse technique was used to isolate Candida species from 149 healthy dentate subjects. Candida species were cultured on Sabouraud's dextrose agar plates and identified by germ-tube test and the automated Vitek(R) system biochemical yeast card. According to the PI and GI scores, subjects were divided into different groups of oral hygiene level.

RESULTS

Candida species were isolated from 86 (57.7%) subjects. The prevalence of candidal carriage increased significantly as a function of age (P = 0.023), but was comparable between males and females (58.7% and 56.7% respectively; P = 0.87). Oral candidal carriage rate and density were not affected by the levels of dental plaque or gingival condition. The prevalence of oral candididal carriage was significantly higher in the subjects who were not using dental floss compared with those who were using dental floss (P = 0.032).

CONCLUSION

Oral hygiene status, as determined by the PI and the GI scores per se, does not affect oral candidal colonization in healthy dentate subjects.

The effects of orthodontic appliances on Candida in the human mouth

BACKGROUND

Candida is an opportunistic pathogen present in about 50-60% of the healthy human population, and becomes pathogenic when the host immune defence is undermined such as in HIV infection. Adhesion and colonization of the oral cavity by Candida albicans is an initial step in candidosis, and the presence of orthodontic and other oral appliances seems to alter the oral ecological environment, hence may tip the balance to favour the candidal presence.

OBJECTIVE

The purpose of this paper was to review the literature with specific attention to prevalence; intra-oral density of the candidal organisms; and Candida carriage status in orthodontic patients before, during, and after treatment.

CONCLUSIONS

The limited amount of literature demonstrated that the density of Candida increases; the most common Candida species isolated in the orthodontic patients was C. albicans; and that there seems to be a direct relationship between the presence of a removable appliance, Candida, and low salivary pH levels. No healthy patients developed Candida infection from the orthodontic appliances. However, there seems to be a trend that some non-Candida carriers converted to Candida carriers following the insertion of the appliances by unknown mechanism. This may indicate a more cautious approach when providing orthodontic treatments to immunocompromised children concerning the possible increased risk of candidal infection.