Oral Candida: clearance, colonization, or candidiasis?

Multilocus sequence typing of Candida albicans oral isolates reveals high genetic relatedness of mother-child dyads in early life

Candida albicans is a pathogenic fungus recently recognized for its role in severe early childhood caries development (S-ECC). C. albicans oral colonization begins at birth, but the extent of the mother's involvement in yeast transmission to their children is unclear, therefore, this study used a prospective mother-infant cohort to investigate the maternal contribution of C. albicans oral colonization in early life. Oral samples were collected from 160 mother-child dyads during pregnancy and from birth to two years of life. We used whole-genome sequencing to obtain the genetic information of C. albicans isolates and examined the genetic relatedness of C. albicans between mothers and their children using Multilocus Sequence Typing. Multivariate statistical methods were used to identify factors associated with C. albicans' acquisition (horizontal and vertical transmissions). Overall, 227 C. albicans oral isolates were obtained from 93 (58.1%) of mother-child pairs. eBURST analysis revealed 16 clonal complexes, and UPGMA analysis identified 6 clades, with clade 1 being the most populated 124 isolates (54.6%). Significantly, 94% of mothers and children with oral C. albicans had highly genetically related strains, highlighting a strong maternal influence on children's C. albicans acquisition. Although factors such as race, ethnicity, delivery method, and feeding behaviors did not show a significant association with C. albicans vertical transmission, the mother's oral hygiene status reflected by plaque index (PI) emerged as a significant factor; Mothers with higher dental plaque accumulation (PI >=2) had a significantly increased risk of vertically transmitting C. albicans to their infants [odds ratio (95% confidence interval) of 8.02 (1.21, 53.24), p=0.03]. Furthermore, Black infants and those who attended daycare had an elevated risk of acquiring C. albicans through horizontal transmission (p <0.01). These findings highlight the substantial role of maternal transmission in the oral acquisition of C. albicans during early life. Incorporating screening for maternal fungal oral carriage and implementing oral health education programs during the perinatal stage may prove valuable in preventing fungal transmission in early infancy.

Storage-related stability and antimicrobial efficacy of bottled, neutral-pH Electrolysed Oxidising Water

OBJECTIVES

Denture stomatitis is prevalent in older people and poses serious health risks. Ready-to-use (RTU) neutral-pH Electrolysed Oxidizing Water (EOW) is an effective environmental disinfectant used in residential care settings and geriatric wards. However, the influence of storage on stability and effectiveness for denture disinfection has not been established. This research investigated the storage-related stability and antimicrobial activity of RTU EOW, and its efficacy against Candida albicans biofilms formed on denture resin.

METHODS

The pH, oxidation/reduction potential (mV), available chlorine content (mg/L) and [HOCl] (mM) of RTU EOW (Envirolyte, New Zealand) solutions (n = 22) were measured from bottle opening to 28 days following storage at 4 °C, room temperature (RT) or 37 °C. Staphylococcus aureus and C. albicans cells were incubated in 80% EOW for contact times (CTs) up to 15 min and colony-forming units (cfu) determined. Minimum inhibitory concentrations (MIC90 EOW-HOCl) after CTs up to five minutes were determined for S. aureus and C. albicans reference strains and clinical isolates. C. albicans-denture resin disc biofilms were assessed after a five-minute CT with undiluted EOW by XTT-metabolic activity assay.

RESULTS

[HOCl] remained stable when RTU EOW was stored at 4 °C or RT for five months after manufacture. One-minute CT resulted in log10 cfu reductions of >6 for S. aureus and >5 for C. albicans. Mean MIC90 for five-minute CT was 37 µM (S. aureus) and 54 µM (C. albicans). Undiluted EOW reduced C. albicans biofilm metabolic activity by 86%.

CONCLUSIONS

RTU neutral-pH EOW is stable over five-months storage and is an effective denture disinfectant.

CLINICAL SIGNIFICANCE

The efficacy of the RTU neutral EOW against C. albicans isolates and biofilms formed on denture resin surfaces supports its use as a denture disinfectant and can inform future research to assess its potential for preventing denture-related oral Candida infections in the older population, especially in resource-limited communities.

Streptococcus mutans sigX-inducing peptide inhibits the virulence of Candida albicans and oral candidiasis through the Ras1-cAMP-Efg1 pathway

Oral candidiasis is the most common fungal infectious disease in the human oral cavity, and Candida albicans is the major pathogenic agent. Increasing drug resistance and the lack of new types of antifungals greatly increase the challenges for treating fungal infections. Targeting hyphal transition provides a promising strategy to inhibit the virulence of C. albicans and overcome drug resistance. This study aimed to investigate the effects and mechanisms of sigX-inducing peptide (XIP), a quorum-sensing signal peptide secreted by Streptococcus mutans, on C. albicans hyphal development and biofilm formation in vitro and oropharyngeal candidiasis in vivo. XIP significantly inhibited C. albicans yeast-to-hypha transition and biofilm formation in a dose-dependent manner from 0.01 to 0.1 µM. XIP significantly downregulated expression of genes from the Ras1-cAMP-Efg1 pathway (RAS1, CYR1, TPK2, EFG1 and UME6), a key pathway to regulate C. albicans hyphal development. Importantly, XIP reduced the levels of key molecules cAMP and ATP from this pathway, while the addition of exogenous cAMP and overexpression of RAS1 restored the hyphal development inhibited by XIP. XIP also lost its hyphal inhibitory effects on ras1Δ/Δ and efg1Δ/Δ strains. These results further confirmed that XIP inhibited hyphal development through downregulation of the Ras1-cAMP-Efg1 pathway. A murine oropharyngeal candidiasis model was employed to evaluate the therapeutic effects of XIP on oral candidiasis. XIP effectively reduced the infected epithelial area, fungal burden, hyphal invasion and inflammatory infiltrates. These results revealed the antifungal effects of XIP, and highlighted that XIP can be a potential antifungal peptide against C. albicans infection.

Antifungal Susceptibility of Oral Candida Isolates from Mother-Infant Dyads to Nystatin, Fluconazole, and Caspofungin

The carriage of Candida albicans in children's oral cavities is associated with a higher risk for early childhood caries, so controlling this fungus in early life is essential for preventing caries. In a prospective cohort of 41 mothers and their children from 0 to 2 years of age, this study addressed four main objectives: (1) Evaluate in vitro the antifungal agent susceptibility of oral Candida isolates from the mother-child cohort; (2) compare Candida susceptibility between isolates from the mothers and children; (3) assess longitudinal changes in the susceptibility of the isolates collected between 0 and 2 years; and (4) detect mutations in C. albicans antifungal resistance genes. Susceptibility to antifungal medications was tested by in vitro broth microdilution and expressed as the minimal inhibitory concentration (MIC). C. albicans clinical isolates were sequenced by whole genome sequencing, and the genes related to antifungal resistance, ERG3, ERG11, CDR1, CDR2, MDR1, and FKS1, were assessed. Four Candida spp. (n = 126) were isolated: C. albicans, C. parapsilosis, C. dubliniensis, and C. lusitaniae. Caspofungin was the most active drug for oral Candida, followed by fluconazole and nystatin. Two missense mutations in the CDR2 gene were shared among C. albicans isolates resistant to nystatin. Most of the children's C. albicans isolates had MIC values similar to those from their mothers, and 70% remained stable on antifungal medications from 0 to 2 years. For caspofungin, 29% of the children's isolates showed an increase in MIC values from 0 to 2 years. Results of the longitudinal cohort indicated that clinically used oral nystatin was ineffective in reducing the carriage of C. albicans in children; novel antifungal regimens in infants are needed for better oral yeast control.

Effects of Nystatin oral rinse on oral Candida species and Streptococcus mutans among healthy adults

OBJECTIVES

To examine the effect of Nystatin oral rinse on oral Candida species and Streptococcus mutans carriage.

MATERIALS AND METHODS

Twenty healthy adults with oral candidiasis participated in the single-arm clinical trial and received Nystatin oral rinse for 7 days, 4 applications/day, and 600,000 International Units/application. Demographic-socioeconomic-oral-medical conditions were obtained. Salivary and plaque Candida species and Streptococcus mutans were assessed at baseline and 1-week and 3-month follow-ups. Twenty-four salivary cytokines were assessed. Candida albicans isolates underwent Nystatin susceptibility test.

RESULTS

Half of participants (10/20) were free of salivary C. albicans after using Nystatin rinse. Salivary S. mutans was significantly reduced at 3-month follow-up (p < 0.05). Periodontal status reflected by bleeding-on-probing was significantly improved at 1-week and 3-month follow-ups (p < 0.05). Plaque accumulation was significantly reduced at 1-week follow-up (p < 0.05). Interestingly, the responses to Nystatin oral rinse were not associated with race, gender, age, oral hygiene practice, adherence to Nystatin rinse, or sweet consumption (p > 0.05). No C. albicans isolates were resistant to Nystatin. Furthermore, salivary cytokine eotaxin and fractalkine were significantly reduced at 3-month follow-up among participants who responded to Nystatin rinse (p < 0.05).

CONCLUSIONS

The study results indicate that oral antifungal treatment had an effect on S. mutans salivary carriage. Future clinical trials are warranted to comprehensively assess the impact of antifungal treatment on the oral flora other than S. mutans and Candida.

CLINICAL RELEVANCE

Due to the potential cariogenic role of oral Candida species, antifungal approaches shed new light on the prevention and management of dental caries from a fungal perspective.

Adhesion of Yeast and Bacteria to Oral Surfaces

Colonization of surfaces in the human body by microorganisms is an early, essential, step in the initiation of infectious disease. We have developed in vitro assays to investigate interactions between yeast or bacterial cells and human tissues, fluids, or prostheses. Such assays can be used to identify the adhesins, ligands, and receptors involved in these interactions, for example, by determining which components of the microbe or human tissue/fluid interfere with adherence in the assay. The assays can also be applied to find ways of preventing adhesion, and subsequent disease, by investigating the effects of different conditions and added compounds on adherence in the in vitro assays. Here we describe assays for measuring adhesion of the oral yeast Candida albicans, a common commensal and opportunistic pathogen, or the bacterium Staphylococcus epidermidis, which is not normally pathogenic but is known to form biofilms on medical prostheses. The assays described belong to two approaches to investigating adhesion and biofilm formation: (i) retention at a fixed time point following liquid washes, and (ii) retention against a continuous flow of medium.

Oral microbiota associated with gingiva of healthy, gingivitis and periodontitis cases

Oral microbes coexist with each other in a symbiotic relationship or as commensals in healthy body. Teeth and oral cavity harbor diverse community of fungi and bacteria. This study focused on bacterial and fungal component of gingiva, where the last occupy little attention. In addition to study the antimicrobial activity of toothpastes, mouth washes and natural oils against microorganisms. Sixty swabs from outer surfaces of gingiva in healthy persons, as well as patients complaining of gingivitis and periodontitis were collected for fungal and bacterial analyses. Sensitivity of the isolated microorganisms to some pharmaceutical preparations and natural oils was also performed. Ten fungal and 9 bacterial species were identified. There is a highly significant variation in the frequency of Klebsiella pneumonia among healthy, gingivitis and periodontitis. Also, Candida tropicalis and cocci bacteria showed significant diversity among the three tested groups. Among pharmaceutical preparations (toothpastes and mouth washes) and natural oils, Paradontax, Hexitol and clove oil showed the best antimicrobial activity against tested fungal and bacterial strains. Although, minimum inhibition concentrations (MICs) of clove oil were high compared to Paradontax and Hexitol, nevertheless, it is highly recommended as both antifungal and antibacterial agent against oral pathogenic microorganisms, because it is a natural compound and nearly devoid of side effects.

Candida Carriers among Individuals with Tongue Piercing—A Real-Time PCR Study

Among the local factors for oral candidiasis, the piercing of the tongue is recognized by some authors as a risk factor for the colonization of Candida albicans. There are few case reports in which Candida spp. colonization and infection are associated with tongue piercing but only one microbiological study supports this hypothesis in general. The aim of this study was to examine this possible association between the presence of both tongue piercing and Candida spp. in healthy individuals. Positive results for tongue colonization with Candida spp. were found in four (12.9%) of the tongue-pierced subjects and in three (9.67%) subjects of the control group (p = 0.550). All samples were identified as Candida albicans. The univariate and logistic regression analyses of possible risk factors for tongue colonization revealed that gender (p = 0.024), smoking more than 10 cigarettes per day (p = 0.021), and improper hygiene (p = 0.028) were statistically significant influencing factors in the multivariate analysis. The results suggest that the piercing of the tongue is not a risk factor for colonization of Candida spp.

Oral Fungal Infections: Past, Present, and Future

Oral fungal infections have afflicted humans for millennia. Hippocrates (ca. 460-370 BCE) described two cases of oral aphthae associated with severe underlying diseases that could well have been oral candidiasis. While oral infections caused by other fungi such as cryptococcosis, aspergillosis, mucormycosis, histoplasmosis, blastomycosis, and coccidioidomycosis occur infrequently, oral candidiasis came to the fore during the AIDS epidemic as a sentinel opportunistic infection signaling the transition from HIV infection to AIDS. The incidence of candidiasis in immunocompromised AIDS patients highlighted the importance of host defenses in preventing oral fungal infections. A greater understanding of the nuances of human immune systems has revealed that mucosal immunity in the mouth delivers a unique response to fungal pathogens. Oral fungal infection does not depend solely on the fungus and the host, however, and attention has now focussed on interactions with other members of the oral microbiome. It is evident that there is inter-kingdom signaling that affects microbial pathogenicity. The last decade has seen significant advances in the rapid qualitative and quantitative analysis of oral microbiomes and in the simultaneous quantification of immune cells and cytokines. The time is ripe for the application of machine learning and artificial intelligence to integrate more refined analyses of oral microbiome composition (including fungi, bacteria, archaea, protozoa and viruses—including SARS-CoV-2 that causes COVID-19). This analysis should incorporate the quantification of immune cells, cytokines, and microbial cell signaling molecules with signs of oral fungal infections in order to better diagnose and predict susceptibility to oral fungal disease.

Prevalence of Candida among denture wearers and nondenture wearers

Introduction:

A denture wearer is highly prone to develop Candida-associated denture stomatitis (CADS) due to the conversion of the normal oral commensal Candida spp. into a pathogen under favorable conditions. Immuno-compromised status, trauma from the prosthesis, other systemic conditions, and improper maintenance of the dentures by the patient are few of the causative agents which turn the oral balance into an unhealthy and unsuitable foundation for the wearing of the prosthesis.

Objective:

The objective of this study was to compare subjects wearing complete dentures and nondenture wearers regarding Candida isolates associated with disease and colonization among the different age groups.

Methodology:

A cross-sectional study was conducted among 60 subjects, 30 wearing complete dentures (Group-A) and 30 nondentures wearers (Group-B), were matched for gender, race, and age. The unstimulated saliva sample was collected and cultured in CHROMagar using standard protocols.

Results:

The mean value of the candidal colony-forming units with respect to Group A is Candida Albicans 0.36 ± 2.008, Candida krusei 0.27 ± 1.061, P value Group B: C. albicans 0.73 ± 2.196, C. krusei 0.36 ± 1.084. There was a significant relation between denture wearers and heavy growth of C. albicans and C. krusei in saliva culture with a P value of P-0.054 and P-0.036, respectively.

Conclusions:

These results indicate that denture wearers with oral Candida had a higher prevalence of CADS. Patients with removable prostheses should be informed about the importance of proper prosthesis and personal hygiene since dentures and age-related immunosuppression are both well-known risk factors associated with candidiasis development, the presence of yeast, even in healthy denture wearers, should be considered a risk factor for denture stomatitis that increases with the duration of denture use.

Evaluation of the effect of Jaftex herbal mouthwash on the growth of Candida albicans and Candida tropicalis

Background

Increased resistance of Candida albicans to standard antifungal agents has caused special attention to medicinal plants. The aim of this study was to evaluate the effect of Jaftex mouthwash on the growth of C. albicans and Candida tropicalis.

Methods and Material

In this in vitro study, standard strains of C. albicans and C. tropicalis were used. Jaftex mouthwash was prepared with the active ingredient (10g/100cc) of aqueous extract of oak fruit hull (Jaft), Zataria multiflora, and Satureja bachtiarica. The mouthwash was diluted in half, 8 different concentrations were obtained. 10 μl volume of each dilution was poured on discs mounted linearly on the culture medium inoculated with the target fungus. After 24 h, due to the slow growth rate of these fungi, the Petri dishes were incubated at 37°C and the mean minimum inhibitory concentration (MIC) was determined for each fungus. The modified E. test method was used to measure the MIC of Jaftex mouthwash for the two fungi. The experiment was repeated three times for each fungus and the mean value was measured.

Results

The mean value of MIC for C. albicans and C. tropicalis was 0.0625 (mg/mL) and 0.0833 (mg/mL), respectively. Candida albicans appeared to be more sensitive to Jaftex, but no statistically significant difference was observed.

Conclusion

Jaftex mouthwash inhibits the growth of C. albicans and C. tropicalis. The use of this mouthwash is recommended for treatment of oral candidiasis.

The genotypes and virulence attributes of C. albicans isolates from oral leukoplakia

Background

There is a debate as to whether some types of oral leucoplakias (OL) are caused by Candida species, and whether they contribute to the malignant transformation, associated with a minority of such lesions. As no detailed population analysis of yeast isolates from OL is available, we evaluated the virulence attributes, and genotypes of 35 C. albicans from OL, and compared their genotypes with 18 oral isolates from healthy individuals.

Material and Methods

The virulence traits evaluated were esterase, phospholipase, proteinase, haemolysin and coagulase production, and phenotypic switching activity, and yeast adherence and biofilm formation. DNA from OL and control yeasts were evaluated for A, B or C genotype status.

Results

Phospholipase, proteinase, and coagulase activity and biofilm formation was observed in 80%, 66%, 97 % and 77 % of the isolates, respectively. Phenotypic switching was detected in 8.6%, while heamolytic, and esterase activity and adherence were noted in all isolates.

Conclusions

The genotype A was predominant amongst both the OL and control groups. Due to the small sample size of our study a larger investigation to define the role of candidal virulent attributes in the pathogenicity of OL is warranted, and the current data should serve as a basis until then.

Key words:C. albicans, oral cavity, leukoplakia, virulence factors, genotyping.

Isolation and identification of oral Candida species in potentially malignant disorder and oral squamous cell carcinoma

CONTEXT

Oral cancer is one of the ten most common cancers in the world. More than 95% of the carcinomas of the oral cavity are of squamous cell type in nature. Oral Candida is a "yeast-like opportunistic pathogen." The Candida genus is comprised of over 150 species of asporogenous "yeast-like" fungi.

AIM AND OBJECTIVES

The aim of study is to correlate the association of oral fungal infection in progression of oral squamous cell carcinoma (OSCC) and potentially malignant disorders. The current study was undertaken to probe the isolation and identification of oral Candida species in potentially malignant disorder and OSCC versus normal oral mucosa.

MATERIALS AND METHODS

Twenty patients for each abovementioned three lesions were randomly selected by using swabs. These swabs were subsequently inoculated in agar medium. Candida grows as white, convex colonies. Samples growing 1-3 colony-forming units (CFUs) were considered normal flora of the oral cavity. The specimens showing moderate to heavy growth were subjected to tests for identification of species of Candida. The chromogenic medium, HiMedia CHROMagar, has chromogenic substances which helps in the quick detection of Candida species, based on the reactions between the extract enzymes of the dissimilar species and the chromogenic substances.

STATISTICAL ANALYSIS

Chi-square test, one-way analysis of variance test, and post hoc Tukey's test were utilized.

RESULTS

According to our study, Candida albicans, Candida krusei, Candida tropicalis, and Candida parapsilosis in the culture were found to be in increasing incidence from healthy, OSCC, and oral potentially malignant disorders (OPMDs). These results clearly indicated that Candida species are increasing in the CFUs (P < 0.0001).

CONCLUSION

Our study showed a higher intensity of Candida in OPMD and squamous cell carcinoma patients with results. The increasing CFU level and hyphae of Candida species in individual biopsy tissue with oral potentially malignant lesions to OSCC suggest that this pathogen plays a role in disease development and could aid in identifying the pathogenic commensal.

Artemisinin elevates ergosterol levels of Candida albicans to synergise with amphotericin B against oral candidiasis

Oral candidiasis, especially caused by Candida albicans, is the most common fungal infection of the oral cavity. The increase in drug resistance and lack of new antifungal agents call for new strategies of antifungal treatment. This study repurposed artemisinin (Art) as a potentiator to the polyene amphotericin B (AmB) and characterised their synergistic mechanism against C. albicans and oral candidiasis. The synergistic antifungal activity between Art and AmB was identified by the checkerboard and recovery plate assays according to the fractional inhibitory concentration index (FICI). Art showed no antifungal activity even at >200 mg/L. However, it significantly reduced AmB dosages against the wild-type strain and 75 clinical isolates of C. albicans (FICI ≤ 0.5). Art significantly upregulated expression of genes from the ergosterol biosynthesis pathway (ERG1, ERG3, ERG9 and ERG11), as shown by RT-qPCR, and elevated the ergosterol content of Candida cells. Increased ergosterol content significantly enhanced binding between fungal cells and the polyene agent, resulting in sensitisation of C. albicans to AmB. Drug combinations of Art and AmB showed synergistic activity against oral mucosal infection in vivo by reducing the epithelial infection area, fungal burden and inflammatory infiltrates in murine oropharyngeal candidiasis. These findings indicate a novel synergistic antifungal drug combination and a new Art mechanism of action, suggesting that drug repurposing is a clinically practical means of antifungal drug development and treatment of oral candidiasis.

Vulvovaginal candidiasis in Iran: A systematic review and meta-analysis on the epidemiology, clinical manifestations, demographic characteristics, risk factors, etiologic agents and laboratory diagnosis

Vulvovaginal candidiasis is a global issue of concern due to its association with economic costs, sexually transmitted infections, and ascending genital tract diseases. This infection affects 75% of women on at least one occasion over a lifetime. The present systematic review and meta-analysis is the first to determine the prevalence of vulvovaginal candidiasis in Iranian women. We searched national (SID, IranDoc, Iranmedex, and Magiran) and international (PubMed, Scopus, Google Scholar, and web of science) databases for studies published between May 2000 until May 2020 reporting the epidemiologic features of vulvovaginal candidiasis in Iranian women. Inclusion and exclusion criteria were defined to select eligible studies. Data were extracted and presented according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The results of the meta-analysis were visualized as a forest plot representing the prevalence estimates of each study. Heterogeneity was also analyzed using the I², and Chi² statistics. The literature search revealed 1929 studies, of which 39 studies met the eligibility criteria, consisting of 10536 women with vulvovaginal symptoms from 24 different cities covering all parts of Iran. The city with the highest number of studies was Tehran (5/39). The overall prevalence of vulvovaginal candidiasis among Iranian women was 47% (95% CI, 0/38-0/55%) and Candida albicans was the most prevalent etiologic agent. The use of oral contraceptive pills (OCPs) was the predominant risk factor for developing vulvovaginal candidiasis and vaginal cheese-like discharges were the predominant clinical manifestation in Iranian women suffering from vulvovaginal candidiasis. The 25-34-year-old age group has the highest prevalence. A high level of I² (I² = 98.7%, P = 0.000) and Chi² (Chi² = 2993.57, P < 0.001) was obtained among studies, which provides evidence of notable heterogeneity between studies. The present meta-analysis revealed a high prevalence of vulvovaginal candidiasis in Iranian women. Given that this infection is associated with the enhanced susceptibility to sexually transmitted diseases (HIV, chlamydia, genital herpes, genital warts, gonorrhea, hepatitis, syphilis, and trichomoniasis) and also is related to the increased probability of preterm birth, congenital cutaneous candidiasis, preterm labor, and infertility, taking preventive measures such as awareness of patients as well as monitoring and controlling of the syndrome are essential.

Candida albicans Enhances the Progression of Oral Squamous Cell Carcinoma In Vitro and In Vivo

Oral squamous cell carcinoma (OSCC) is associated with oral Candida albicans infection, although it is unclear whether the fungus promotes the genesis and progression of OSCC or whether cancer facilitates fungal growth. In this study, we investigated whether C. albicans can potentiate OSCC tumor development and progression. In vitro, the presence of live C. albicans, but not Candida parapsilosis, enhanced the progression of OSCC by stimulating the production of matrix metalloproteinases, oncometabolites, protumor signaling pathways, and overexpression of prognostic marker genes associated with metastatic events. C. albicans also upregulated oncogenes in nonmalignant cells. Using a newly established xenograft in vivo mouse model to investigate OSCC-C. albicans interactions, oral candidiasis enhanced the progression of OSCC through inflammation and induced the overexpression of metastatic genes and significant changes in markers of the epithelial-mesenchymal transition. Finally, using the 4-nitroquinoline 1-oxide (4NQO) murine model, we directly correlate these in vitro and short-term in vivo findings with the progression of oncogenesis over the long term. Taken together, these data indicate that C. albicans upregulates oncogenes, potentiates a premalignant phenotype, and is involved in early and late stages of malignant promotion and progression of oral cancer. IMPORTANCE Oral squamous cell carcinoma (OSCC) is a serious health issue worldwide that accounts for 2% to 4% of all cancer cases. Previous studies have revealed a higher yeast carriage and diversity in oral cancer patients than in healthy individuals. Furthermore, fungal colonization in the oral cavity bearing OSCC is higher on the neoplastic epithelial surface than on adjacent healthy surfaces, indicating a positive association between oral yeast carriage and epithelial carcinoma. In addition to this, there is strong evidence supporting the idea that Candida contributes to carcinogenesis events in the oral cavity. Here, we show that an increase in Candida albicans burden promotes an oncogenic phenotype in the oral cavity.

Clinical Characteristics and Relevance of Oral Candida Biofilm in Tongue Smears

Dimorphic Candida exist as commensal yeast carriages or infiltrate hyphae in the oral cavity. Here, we investigated the clinical relevance of Candida hyphae in non-pseudomembranous oral candidiasis (OC) by smears of tongue biofilms. We conducted a retrospective study of 2829 patients who had had tongue smears regardless of OC suspicion. Clinical characteristics were evaluated using a novel method of assessing hyphae. Clinical factors (moderate/severe stimulated pain, pain aggravated by stimulation, tongue dorsum appearance and initial topical antifungal use) were highly significant in the high-grade hyphae group but were statistically similar in the low-grade hyphae and non-observed hyphae group, suggesting low-grade hyphae infection as a subclinical OC state. In addition to erythematous candidiasis (EC), a new subtype named "morphologically normal symptomatic candidiasis" (MNSC) with specific pain patterns and normal tongue morphology was identified. MNSC had a significantly higher proportion of moderate and severe stimulated pain cases than EC. Low unstimulated salivary flow rate (<0.1 mL/min) was found to be a common risk factor in MNSC and EC. In non-pseudomembranous OC, pain patterns were dependent on Candida hyphae degree regardless of tongue dorsum morphology. Morphologic differences seen in high-grade hyphae infection were not associated with systemic diseases or nutritional deficiencies.

Roles for Structural Biology in the Discovery of Drugs and Agrochemicals Targeting Sterol 14α-Demethylases

Antifungal drugs and antifungal agrochemicals have significant limitations. These include several unintended consequences of their use including the growing importance of intrinsic and acquired resistance. These problems underpin an increasingly urgent need to improve the existing classes of antifungals and to discover novel antifungals. Structural insights into drug targets and their complexes with both substrates and inhibitory ligands increase opportunity for the discovery of more effective antifungals. Implementation of this promise, which requires multiple skill sets, is beginning to yield candidates from discovery programs that could more quickly find their place in the clinic. This review will describe how structural biology is providing information for the improvement and discovery of inhibitors targeting the essential fungal enzyme sterol 14α-demethylase.

Highly efficient antibiofilm and antifungal activity of green propolis against Candida species in dentistry materials

This study evaluated the effect of green propolis extract on the adhesion and biofilm formation of Candida species in dentistry materials. Phytochemical analysis of green propolis extract was performed by high-performance liquid chromatography. Adhesion was quantified by counting the number of yeast cells adherent to dental material fragments in a Neubauer chamber. Biofilm formation was determined by counting colony-forming units recovered from dental material fragments. The intensity of biofilm adhesion was classified as negative, weak, moderate, strong, or very strong. Fifteen compounds, mainly flavonoids, were identified in green propolis extract. All strains adhered to and formed biofilms on the surfaces of the orthodontic materials studied. On steel and resin, yeast cell adhesion intensities were weak at all incubation times, except for those of Candida parapsilosis and C. tropicalis, which were moderate at 12 h. At 24 and 48 h, C. albicans formed biofilms on steel with moderate adhesion affinities; at 24 and 48 h, C. parapsilosis formed biofilms with very strong affinities. C. tropicalis formed biofilms with strong and very strong affinities at 24 and 48 h, respectively. On resin, all species displayed strong affinity for biofilm formation at 24 and 48 h, except for C. tropicalis, which displayed very strong affinity at only 48 h. Green propolis extract displayed antifungal activity and inhibited both adhesion and biofilm formation at 2.5 μg/mL. This study reinforces the idea that green propolis has antifungal activity and interferes with the virulence of Candida species.

The influence of Azadirachta indica, Melaleuca alternifolia, and Cocos nucifera on Candida albicans strain in tissue conditioner at varying time intervals

Aim:

The search for alternative therapies for oral candidiasis is a necessity and the use of medicinal plants seems to be one such promising solutions. Incorporation of phytotherapeutic agents, Azadirachta indica (neem oil), Melaleuca alternifolia oil (tea tree oil), and Cocos nucifera oil (coconut oil), were tested for their efficacy as antifungal agents against Candida albicans. Next, the efficacy of these three antifungal agents when incorporated in a soft relining material at minimum inhibitory concentration (MIC) was evaluated.

Settings and Design:

Evaluative - In-vitro study design.

Materials and Methods:

The MIC against C. albicans ATCC 24433 was calculated for M. alternifolia oil, A. indica oil, and C. nucifera oil using the broth microdilution method. Based on the preliminary screening results for MIC, tissue conditioner samples were prepared to evaluate the zone of inhibition (ZOI) and MIC. Antifungal activity of the MIC of the three oils was assessed and compared by measuring the mean ZOI. Antifungal activity of the three oils was assessed using one-way analysis of variance (ANOVA) and post hoc test.

Statistical Analysis Used:

Oneway ANOVA and post hoc Tukey honestly significant difference test.

Results:

Inhibition against C. albicans was exhibited when 20% v/v, 25% v/v, and 15% v/v of C. nucifera oil, M. alternifolia oil, and A. indica oil were used, respectively. The results of ANOVA and post hoc test at the end of 48 h and 7 days suggested that all three oils were significantly different from each other (P = 0.000) and A. indica/neem oil with 15% concentration had the best antifungal activity at the end of 48 h and 7 days.

Conclusion:

The antimycotic activity of M. alternifolia, C. nucifera, and A. indica mixed with the Visco-gel tissue conditioner can be used as an alternative therapy for denture stomatitis.

Candida-Associated Denture Stomatitis and Murine Models: What Is the Importance and Scientific Evidence?

Considering the high prevalence and recurrence of Candida-associated denture stomatitis (CADS), in vivo studies in animal models are necessary before those in humans to evaluate new therapeutic strategies. This study aimed to review the literature on murine models of CADS induction using acrylic intraoral devices simulating dentures. Rats are recommended as experimental animals in these models as well as the adoption of a pasty diet. For maintenance in the proper position during the experiments, intraoral appliances must be obtained by individual impressions, using and retained exclusively by cementation on the molars. The region of interest for histopathological analysis was standardized as that corresponding to the area between the first molars. However, there is no consensus among the studies on the CADS induction rat models in relation to the Candida albicans inoculation and need for immunosuppression and/or administration of antibacterial drugs of animals. The greatest difficulty of the available models refers to maintaining the course of the lesion for a sufficient period to evaluate the effectiveness of the proposed treatment, considering the rapid and efficient murine immune response to candidal colonization. Therefore, future studies are necessary for the development of a robust and reproducible CADS model.

Candida albicans Antifungal Resistance and Tolerance in Bloodstream Infections: The Triad Yeast-Host-Antifungal

Candida albicans represents the most frequent isolated yeast from bloodstream infections. Despite the remarkable progress in diagnostic and therapeutic approaches, these infections continue to be a critical challenge in intensive care units worldwide. The economic cost of bloodstream fungal infections and its associated mortality, especially in debilitated patients, remains unacceptably high. Candida albicans is a highly adaptable microorganism, being able to develop resistance following prolonged exposure to antifungals. Formation of biofilms, which diminish the accessibility of the antifungal, selection of spontaneous mutations that increase expression or decreased susceptibility of the target, altered chromosome abnormalities, overexpression of multidrug efflux pumps and the ability to escape host immune defenses are some of the factors that can contribute to antifungal tolerance and resistance. The knowledge of the antifungal resistance mechanisms can allow the design of alternative therapeutically options in order to modulate or revert the resistance. We have focused this review on the main factors that are involved in antifungal resistance and tolerance in patients with C. albicans bloodstream infections.

Non-plaque-induced gingival diseases

While plaque-induced gingivitis is one of the most common human inflammatory diseases, several non-plaque-induced gingival diseases are less common but often of major significance for patients. The non-plaque-induced gingival lesions are often manifestations of systemic conditions, but they may also represent pathologic changes limited to gingival tissues. A classification is proposed, based on the etiology of the lesions and includes: Genetic/Developmental disorders; Specific infections; Inflammatory and immune conditions and lesions; Reactive processes; Neoplasms; Endocrine, Nutritional and metabolic diseases; Traumatic lesions; and Gingival pigmentation.

Non-plaque-induced gingival diseases

While plaque-induced gingivitis is one of the most common human inflammatory diseases, several non-plaque-induced gingival diseases are less common but often of major significance for patients. The non-plaque-induced gingival lesions are often manifestations of systemic conditions, but they may also represent pathologic changes limited to gingival tissues. A classification is proposed, based on the etiology of the lesions and includes: Genetic/Developmental disorders; Specific infections; Inflammatory and immune conditions and lesions; Reactive processes; Neoplasms; Endocrine, Nutritional and metabolic diseases; Traumatic lesions; and Gingival pigmentation.

Integrated Analysis of Clinical and Microbiome Risk Factors Associated with the Development of Oral Candidiasis during Cancer Chemotherapy

Oral candidiasis is a common side effect of cancer chemotherapy. To better understand predisposing factors, we followed forty-five subjects who received 5-fluorouracil- or doxorubicin-based treatment, during one chemotherapy cycle. Subjects were evaluated at baseline, prior to the first infusion, and at three additional visits within a two-week window. We assessed the demographic, medical and oral health parameters, neutrophil surveillance, and characterized the salivary bacteriome and mycobiome communities through amplicon high throughput sequencing. Twenty percent of all subjects developed oral candidiasis. Using multivariate statistics, we identified smoking, amount of dental plaque, low bacteriome and mycobiome alpha-diversity, and the proportions of specific bacterial and fungal taxa as baseline predictors of oral candidiasis development during the treatment cycle. All subjects who developed oral candidiasis had baseline microbiome communities dominated by Candida and enriched in aciduric bacteria. Longitudinally, oral candidiasis was associated with a decrease in salivary flow prior to lesion development, and occurred simultaneously or before oral mucositis. Candidiasis was also longitudinally associated with a decrease in peripheral neutrophils but increased the neutrophil killing capacity of Candida albicans. Oral candidiasis was not found to be associated with mycobiome structure shifts during the cycle but was the result of an increase in Candida load, with C. albicans and Candida dubliniensis being the most abundant species comprising the salivary mycobiome of the affected subjects. In conclusion, we identified a set of clinical and microbiome baseline factors associated with susceptibility to oral candidiasis, which might be useful tools in identifying at risk individuals, prior to chemotherapy.

Oral Candidal carriage and associated risk indicators among adults in Sakaka, Saudi Arabia

BACKGROUND

Candida is a ubiquitous organism in nature which inhabits the oral cavity as part of the normal microbial flora. The oral carriage of Candida is perpetuated by several predisposing factors.

METHODS

This cross-sectional study was designed to investigate the carriage rate of Candida among 104 voluntary adults at the college of medicine - Jouf University. The concentrated oral rinse technique using Sabouraud Dextrose agar medium supplemented with 0.05% Chloramphenicol was used to isolate Candida. The relative factors affecting the colonization of Candida and the concentration of each type were also determined.

RESULTS

Candida species were isolated from the oral cavity of 45 (43.4%) subjects. Of these 55.6% were identifies as C. albicans as determined by the Vitek 2 compact system. Other Candida species were represented by C. glabrata (11.1%), C. krusei (11.1%), C. dubliniensis (8.9%), C. parapsilosis (6.7%), C. tropicalis (4.4%), and C. famata (2.2%). Subjects with very poor plaque status, severe gingivitis and diabetes had significantly (P = 0.001) high concentration of Candida spp.

CONCLUSION

Plague, severe gingivitis, and diabetes were found to be significantly associated with higher Candida colonization.

Yeast Species in the Oral Cavities of Older People: A Comparison between People Living in Their Own Homes and Those in Rest Homes

Oral candidiasis is prevalent among older people due to predisposing factors such as impaired immune defenses, medications and denture use. An increasing number of older people live in rest home facilities and it is unclear how this institutionalized living affects the quantity and type of fungi colonizing these people's oral cavities. Smears and swabs of the palate and tongue and saliva samples were taken from participants residing in rest homes (RH; n = 20) and older people living in their own homes (OH; n = 20). Yeast in samples were quantified and identified by culturing on CHROMagar Candida and sequencing the ITS2 region of rDNA. A higher proportion of RH residents had Candida hyphae present in smears compared to OH participants (35% vs. 30%) although this difference was not statistically significant (p = 0.74). RH residents had, on average, 23 times as many yeast per mL saliva as OH participants (p = 0.01). Seven yeast species were identified in OH samples and only five in RH samples, with Candida albicans and Candida glabrata being the most common species isolated from both participant groups. The results indicate that older people living in aged-care facilities were more likely to have candidiasis and have a higher yeast carriage rate than similarly aged people living at home. This may be due to morbidities which led to the need for residential care and/or related to the rest home environment.

Preliminary study of the oral mycobiome of children with and without dental caries

Children’s oral health is in a dire state, with dental decay (caries) being one of the most common chronic diseases. While the role of bacteria in the oral microbiome and dental caries is established, the contribution of fungi is relatively unknown. We assessed the oral mycobiome in childhood (n = 17), to determine if the composition of fungi varies between children with and without caries. Oral mycobiome composition was assessed by using Illumina MiSeq to sequence the ITS2 region, which was amplified from dental plaque. This revealed that the oral mycobiome in the investigated children contained 46 fungal species. Candida albicans was the most abundant species and was ubiquitous in all samples, indicating this species may not be involved in caries development as previously suggested. While the overall diversity of fungi was similar, independent of caries status (p > 0.05), we found caries influenced the abundance of specific fungi. Children without caries had a significantly higher abundance of 17 species compared to children with caries, which had three enriched species (p < 0.001). While the differentially abundant species between health and caries may be specific to an Australian population, our findings indicate the mycobiome plays a role in oral health.

Oral Fungal Infections: Diagnosis and Management

Oral and maxillofacial fungal infections can appear in high-risk patients, including those immunocompromised. This article explores common oral manifestations of fungal infections in the oral cavity as primary lesions or as a result of disseminated disease. By far the most common oral fungal infection experienced in dentistry is oral candidiasis, which is reviewed in depth from simple oral infections to invasive candidiasis. The review aids the dental practitioner in understanding the full scope of Candida infections and other fungal infections. In addition to candidiasis, various other fungal infections are reviewed, including mucormycosis, aspergillosis, blastomycosis, histoplasmosis, cryptococcosis, and coccidioidomycosis.

Salivary pH and colonization by oral Candida in children and adolescents submitted to haemodialysis

BACKGROUND

Fungal infections are a serious problem among haemodialysis patients.

AIM

The aims of this study were to estimate the frequency of oral Candida species among children and adolescents undergoing haemodialysis (HD), to identify the isolated species, and to study the relationship between haemodialysis duration, amounts of colony-forming units, and salivary pH.

DESIGN

A matched sample of 52 patients undergoing HD and 52 healthy individuals were selected. The samples were obtained from the dorsum of the tongue, and the colonies were identified through a substrate assimilation test. Stimulated whole saliva was collected from each patient for evaluation of salivary pH.

RESULTS

The frequency of oral Candida species was 34.6% (18/52) and 46.20% (24/52) in the HD and control groups (P = 0.23), respectively. Candida parapsilosis complex was the most frequently isolated fungi species in the HD group (P = 0.03). A HD therapy duration of more than 1 year was statistically correlated with a higher number of colony-forming units (P = 0.03) but was not statistically related to salivary pH.

CONCLUSIONS

Candida parapsilosis complex was the most frequently isolated fungal species in the young HD patients, and the duration therapy was associated with higher oral colonization.

Salivary metals, age, and gender correlate with cultivable oral Candida carriage levels

Background: Little is known about the normal range of metal levels in unstimulated saliva, nor whether these might impact Candida carriage in healthy individuals. Both are important in determining which populations are at risk for candidiasis, as the availability of metal ions can influence the growth and pathogenesis of Candida albicans.

Objective: We quantified salivary metals of healthy individuals to determine the correlation with C. albicans oral colonization.

Design: Unstimulated whole saliva was collected from healthy adults and plated to determine fungal carriage, and metal content was measured using ICP-mass spectrometry (ICP-MS).

Results: Zinc was most abundant, followed by iron, copper, manganese, and nickel. Cultivable oral Candida carriage was found in 48% of people. Total protein levels did not differ in salivas from donors with or without carriage. However, innate fungicidal activity was increased in donors with carriage; correlations between levels of several metals were stronger in salivas with fungal carriage, indicating a shift in the oral environment. Concentrations of copper and manganese, as well as age and gender, were significantly predictive of carriage levels in a multiple regression model.

Conclusions: Salivary copper and manganese content along with age and gender could be used as a predictive metric for individuals that are more susceptible to Candida overgrowth.

Adhesion of Yeast and Bacteria to Oral Surfaces

Colonization of surfaces in the human body by microorganisms is an early, essential, step in the initiation of infectious disease. We have developed in vitro assays to investigate interactions between yeast or bacterial cells and human tissues, fluids, or prostheses. Such assays can be used to identify the adhesins, ligands, and receptors involved in these interactions, for example, by determining which components of the microbe or human tissue/fluid interfere with adherence in the assay. The assays can also be applied to finding ways of preventing adhesion, and subsequent disease, by investigating the effects of different conditions and added compounds on adherence in the in vitro assays.Here we describe assays for measuring adhesion of the oral yeast Candida albicans, a common commensal and opportunistic pathogen, or the bacterium Staphylococcus epidermidis, which is not normally pathogenic but is known to form biofilms on medical prostheses. The assays described belong to two approaches to investigating adhesion and biofilm formation: (1) retention at a fixed time point following liquid washes and (2) retention against a continuous flow of medium.

Characterization of Herbal Antifungal Agent, Origanum vulgare against Oral Candida spp. Isolated from Patients with Candida-Associated Denture Stomatitis: An In vitro Study

Background:

Candida Associated Denture Stomatitis is the prevalent fungal pathosis in denture wearers, especially in immunocompromized patients. Existing antifungal agents are ineffective since the Candida species become resistant and also, they become toxic. Origanum vulgare is a herbal plant with high anti-fungal activity against Candida of blood and urine origin. However, it has never been explored against Candida from oral cavity.

Materials & Methodology:

Dry leaves of the plant were purchased and authenticated. Oil extraction was done using Hydro-distillation method. Clinical isolates of Candida from denture wearers was speciated using CHROMagar. Well Diffusion test was used to confirm the antifungal activity. Hydro-distillation & Maceration methods of extraction were compared. MIC/MFC was determined using CSLI guidelines. Infra-Red Spectroscopy was used to identify the active functional group.

Results:

O.vulgare showed 30±3mm of zone of inhibition as against 19mm for fluconazole. The suitable extraction method was Hydro-distillation. MIC & MFC were found to be 0.024% and 0.097% respectively which was much lesser than for fluconazole (0.25%). The active functional group had chemically similar structure as Carvacrol, usually found in antifungal herbs.

Conclusion:

within the limitations of the study, it was concluded that (a)O.vulgare is anticandidal for clinical isolates of oral Candida, (b) Hydro-distillation is an effective method as compared to Maceration (c) MIC & MFC are much lower than that of fluconazole (d) the major functional group was structurally similar to Carvacrol.

Candida albicans and Early Childhood Caries: A Systematic Review and Meta-Analysis

Oral Candida albicans has been detected in children with early childhood caries (ECC) and has demonstrated cariogenic traits in animal models of the disease. Conversely, other studies found no positive correlation between C. albicans and caries experience in children, while suggesting it may have protective effects as a commensal organism. Thus, this study aimed to examine whether oral C. albicans is associated with ECC. Seven electronic databases were searched. The data from eligible studies were extracted, and the risk of bias was evaluated. A fixed effects model (Mantel-Haenszel estimate) was used for meta-analysis, and the summary effect measure was calculated by odds ratio (OR) and 95% confidence interval (CI). Fifteen cross-sectional studies were included for the qualitative assessment and 9 studies for meta-analysis. Twelve studies revealed higher oral C. albicans prevalence in ECC children than in caries-free children, while 2 studies indicated an equivalent prevalence. A pooled estimate, with OR = 6.51 and 95% CI = 4.94-8.57, indicated a significantly higher ECC experience in children with oral C. albicans than those without C. albicans (p < 0.01). The odds of experiencing ECC in children with C. albicans versus children without C. albicans were 5.26 for salivary, 6.69 for plaque, and 6.3 for oral swab samples. This systematic review indicates that children with oral C. albicans have >5 times higher odds of having ECC compared to those without C. albicans. Further prospective cohort studies are needed to determine whether C. albicans could be a risk factor for ECC, and whether it is dependent on different sample sources (saliva/plaque).

Antifungal activities of the essential oil and its fractions rich in sesquiterpenes from leaves of Casearia sylvestris Sw

Casearia genus (Salicaceae) is found in sub-tropical and tropical regions of the world and comprises about 160-200 species. It is a medicinal plant used in South America, also known as "guaçatonga", "erva-de-tiú", "cafezinho-do-mato". In Brazil, there are about 48 species and 12 are registered in the State of Rio de Janeiro, including Casearia sylvestris Sw. There are many studies related to the chemical profile and cytotoxic activities of extracts from these plants, although few studies about the antifungal potential of the essential oil have been reported. In this work, we have studied the antifungal properties of the essential oil of C. sylvestris leaves, as well as of their fractions, against four yeasts (Saccharomyces cerevisae, Candida albicans, C. glabrata and C. krusei) for the first time. The chemical analysis of the essential oil revealed a very diversified (n = 21 compounds) volatile fraction composed mainly of non-oxygenated sesquiterpenes (72.1%). These sesquiterpenes included α-humulene (17.8%) and α-copaene (8.5%) and the oxygenated sesquiterpene spathulenol (11.8%) were also identified. Monoterpenes were not identified. The fractions are mainly composed of oxygenated sesquiterpenes, and the most active fraction is rich in the sesquiterpene 14-hydroxy -9-epi-β-caryophyllene. This fraction was the most effective in inhibiting the growth of three yeast strains.

Is the oral fungal pathogen Candida albicans a cariogen?

Pathobiology of dental caries is complex. Data from recent molecular microbiologic studies have further redefined the role of the oral microbiome in the etiology of dental caries. This new information challenges the conventional view on the hegemony of classic cariogenic prokaryotes such as Streptococcus mutans in caries etiology, and raises the intriguing possibility of the participation of the eukaryotic oral fungal pathogen Candida in the caries process. The virulence attributes of Candida species such as their acidogenicity and aciduric nature, the ability to develop profuse biofilms, ferment and assimilate dietary sugars, and produce collagenolytic proteinases are all indicative of their latent cariogenic potential. Based on the above, oral candidal counts have been used by some as a caries risk indicator. On the contrary, other studies suggest that Candida is merely a passenger extant in an acidic cariogenic milieu, and not a true pathogen. In this review, we critically examine the varying roles of Candida, and traditionally accepted cariogens such as the mutans group of streptococci in the pathobiology of dental caries. The weight of available data tends to imply that Candida may play a pivotal role as a secondary agent perpetuating the carious process, especially in dentinal caries.

The significance of Candida in the human respiratory tract: our evolving understanding

Candida is an opportunistic pathogen and the most commonly isolated fungal genus in humans. Though Candida is often detected in respiratory specimens from humans with and without lung disease, its significance remains undetermined. While historically considered a commensal organism with low virulence potential, the status of Candida as an innocent bystander has recently been called into question by both clinical observations and animal experimentation. We here review what is currently known and yet to be determined about the clinical, microbiological and pathophysiological significance of the detection of Candida spp. in the human respiratory tract.

Revealing the sequence of interactions of PuroA peptide with Candida albicans cells by live-cell imaging

To determine the mechanism(s) of action of antimicrobial peptides (AMPs) it is desirable to provide details of their interaction kinetics with cellular, sub-cellular and molecular targets. The synthetic peptide, PuroA, displays potent antimicrobial activities which have been attributed to peptide-induced membrane destabilization, or intracellular mechanisms of action (DNA-binding) or both. We used time-lapse fluorescence microscopy and fluorescence lifetime imaging microscopy (FLIM) to directly monitor the localization and interaction kinetics of a FITC- PuroA peptide on single Candida albicans cells in real time. Our results reveal the sequence of events leading to cell death. Within 1 minute, FITC-PuroA was observed to interact with SYTO-labelled nucleic acids, resulting in a noticeable quenching in the fluorescence lifetime of the peptide label at the nucleus of yeast cells, and cell-cycle arrest. A propidium iodide (PI) influx assay confirmed that peptide translocation itself did not disrupt the cell membrane integrity; however, PI entry occurred 25–45 minutes later, which correlated with an increase in fractional fluorescence of pores and an overall loss of cell size. Our results clarify that membrane disruption appears to be the mechanism by which the C. albicans cells are killed and this occurs after FITC-PuroA translocation and binding to intracellular targets.

Secretory component mediates Candida albicans binding to epithelial cells

OBJECTIVES

Candida albicans attaches to oral surfaces via a number of mechanisms including adherence mediated by salivary components adsorbed to the C. albicans cell surface. Our goal was to identify the salivary molecules involved.

MATERIALS AND METHODS

Biotinylated salivary polypeptides that were bound by C. albicans were detected in extracts from washed, saliva-treated yeast cells by polyacrylamide gel electrophoresis and electroblot or immunoblot transfer analysis and purified by electroelution. Purified material was tested for the ability to promote the adherence of radiolabelled C. albicans yeast cells to cultured epithelial monolayers.

RESULTS

Three of the polypeptides bound by C. albicans cells were identified as components of secretory IgA, including secretory component. Using non-denaturing polyacrylamide gel electrophoresis, we demonstrated that secretory component could be detected in its free form in saliva, and was bound by yeast cells. Secretory component which was purified by electroelution from non-denaturing PAGE-separated saliva, without detectable complete IgA, promoted adherence of yeast cells to cultured epithelial monolayers in a dose-dependent fashion.

CONCLUSION

These results indicate that despite the inhibitory effect on adherence of IgA specific to C. albicans, IgA components, in particular secretory component, also promote binding to cultured epithelial monolayers.

Frequency of Candidiasis and Colonization of Candida albicans in Relation to Oral Contraceptive Pills

Background

Candidiasis, the infection caused by Candida albicans, is one of the most common infections of the oral cavity in humans. Candidiasis causes irritation and is known for its carcinogenic effects. Thus, it is important to recognize the predisposing factors for this opportunistic infection. Several previous studies have demonstrated an increased frequency of vaginal candidiasis in relation to oral contraceptive consumption.

Objectives

Only a few studies on the relation between oral contraceptives and oral candidiasis have been previously conducted. This study aims to evaluate the possible relation between oral contraceptive pills and oral candidiasis.

Methods

This analytic, case-control study included 40 non-pregnant women divided into two groups: 20 who used oral contraceptive pills and 20 who did not. The groups were matched according to age, oral health, and past and present medical history. Samples were collected from the tongue’s dorsum using a cotton swab and inoculated on CHROMagar culture plates. The frequency of positive cultures and the number of Candida colonies were compared between the two groups using independent t-tests and Mann-Whitney statistical tests with SPSS18 software.

Results

The frequency of positive cultures of Candida albicans was higher (P value = 0.03) for the case group. Also, the number of C. albicans and C. krusei was significantly higher for the case group compared to the control group (P value = 0.04, P value = 0.03).

Conclusions

The results of the present study demonstrate that oral contraceptives containing estradiol can lead to Candida colonization in the oral cavity. It is recommended that further studies comparing the influence of oral contraceptives on Candida’s adherence to the epithelium is highly recommended.

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.

Culture media profoundly affect Candida albicans and Candida tropicalis growth, adhesion and biofilm development

As there are sparse data on the impact of growth media on the phenomenon of biofilm development for Candida we evaluated the efficacy of three culture media on growth, adhesion and biofilm formation of two pathogenic yeasts, Candida albicans and Candida tropicalis. The planktonic phase yeast growth, either as monocultures or mixed cultures, in sabouraud dextrose broth (SDB), yeast nitrogen base (YNB), and RPMI 1640 was compared, and adhesion as well as biofilm formation were monitored using MTT and crystal violet (CV) assays and scanning electron microscopy. Planktonic cells of C. albicans, C. tropicalis and their 1:1 co-culture showed maximal growth in SDB. C. albicans/C. tropicalis adhesion was significantly facilitated in RPMI 1640 although the YNB elicited the maximum growth for C. tropicalis. Similarly, the biofilm growth was uniformly higher for both species in RPMI 1640, and C. tropicalis was the slower biofilm former in all three media. Scanning electron microscopy images tended to confirm the results of MTT and CV assay. Taken together, our data indicate that researchers should pay heed to the choice of laboratory culture media when comparing relative planktonic/biofilm growth of Candida. There is also a need for standardisation of biofilm development media so as to facilitate cross comparisons between laboratories.

Candida infection in oral leukoplakia: an unperceived public health problem

OBJECTIVES

The study aimed to determine the proportion, known risk factors and etiology for Candida infection in leukoplakia lesions among patients with oral leukoplakia attending the Oral and Maxillofacial Clinic at a Tertiary Care Hospital in Sri Lanka.

MATERIALS AND METHODS

Eighty clinically suspected oral leukoplakia patients were included. Two oral swabs each, from leukoplakia patients: one swab from the lesion and the other one from the contralateral unaffected corresponding area (as a control) were collected. Direct microscopy and culture followed by colony count and phenotypic identification were performed to identify pathogenic Candida species.

RESULTS

Candida infection was seen in 47% of patients with oral leukoplakia. Candida albicans (94.7%) was the most common Candida species followed by Candida tropicalis (5.3%). Majority of Candida-infected lesions were seen in the buccal mucosa region. Alteration of taste (p = 0.021), having other oral lesions (p = 0.008), angular cheilitis (p = 0.024) and periodontitis (p = 0.041) showed a significant association with Candida-associated leukoplakia. Increasing age showed a significant tendency for Candida infection (p = 0.020). Smoking (p = 0.026) and betel-quid chewing (p = 0.006) were also found to be significantly associated, although alcohol consumption alone did not show a significant association. Oral leukoplakia patients who had all three habits: alcohol consumption, smoking and betel-quid chewing had a significant association with Candida infection (p = 0.004).

CONCLUSIONS

Patients who had a combination of risk factors: smoking, betel-quid chewing and alcohol consumption were seen to have a significant association with Candida infection. Further betel-quid chewing alone and smoking singly was also significantly associated with Candida infection in oral leukoplakia.

Alcohol and tobacco consumption affect the oral carriage of Candida albicans and mutans streptococci

This study sought to determine if there is a relationship between the consumption of alcohol and tobacco and oral colonization by mutans streptococci and Candida species. Subjects were recruited from the University Dental Clinic of CEU Cardenal Herrera University (Moncada, Valencia). Information on alcohol and tobacco consumption was obtained by questionnaire. Individual stimulated saliva samples from 105 patients were obtained and selective media was used to isolate and quantify mutans streptococci and Candida spp. colony forming units per millilitre of saliva (CFU ml(-1) ). Samples were stratified by duration and quantity of alcohol and tobacco consumption. Alcohol consumption statistically significantly decreased oral carriage of mutans streptococci, whereas there was no effect on Candida albicans colonization levels. Tobacco users were found to harbour elevated levels of C. albicans; however, there was no observed effect on bacterial colonization by mutans streptococci. The carriage of other species investigated, such as Candida krusei, Candida tropicalis and lactobacilli, do not show a response to the consumption of the stimulants analysed. Microbial colonization of the oral cavity changes in a species-specific manner in response to dietary and social habits such as drinking alcohol and smoking.

SIGNIFICANCE AND IMPACT OF THE STUDY

In this paper, we evaluate the effect of alcohol and tobacco consumption on key species of the oral microflora. Our results show species-specific changes in two major opportunistic pathogens, such as Candida albicans and mutans streptococci, whereas other members of oral microflora are not affected by the consumption of the stimulants studied. We believe this original paper will contribute to raise awareness among the dental community towards a more personalized oral health assessment, taking in consideration alcohol and tobacco consumption in the prevention of specific oral and systemic pathologies.

High Oral Carriage of Non-albicans Candida spp. among HIV-infected individuals

BACKGROUND

Non-albicans Candida (NAC) spp. in immunocompromised patients are linked to invasive infections with narrow treatment choice. This study aimed at comparing the oral colonization of NAC spp. between HIV and non-HIV infected individuals in Mwanza, Tanzania.

METHOD

Oral rinse of 351 HIV-infected and 639 non-HIV infected individuals were collected between March and July 2015. Phenotypic identifications of Candida spp. was done using Candida Chromogenic agar and confirmed by MALDI-TOF MS.

RESULTS

NAC spp. were detected in 36/351 (10.3%) HIV-infected individuals compared to 28/639 (4.4%) of non-HIV infected individuals; P=0.0003. In HIV infected individuals, commonly isolated NAC spp. were Candida tropicalis, 10(2.8%), C. krusei (Issatschenki orientalis) 9(2.6%) and C. glabrata 8(2.3%). While for non-HIV infected individuals C. dubliniensis 8(1.3%) and C. tropicalis 5(0.9%) were commonly detected. As CD4 count/μl decreases by one unit the risk of being colonized by NAC spp. among HIV infected individuals increases by 1% (OR 1.01, 95% CI; 1.001-1.004, P=0.001).

CONCLUSION

The prevalence of NAC spp. is high among HIV-infected individuals with low CD4 count placing them at higher risk of invasive infections. Further studies to investigate the role of NAC spp. in causing invasive infections among immunocompromised patients are recommended.