Oropharyngeal candidosis in the older patient

Title: Chemotherapy-Induced Oral Complications and Prophylaxis Strategies

Cancer is currently a significant therapeutic challenge and is frequently connected with numerous adverse effects. Despite many improvements in chemotherapy, oral complications are common, leading to poor quality of life and chemotherapeutic dose reduction, which impair survival. This review summarizes the most common dental complications in patients receiving chemotherapy. We mainly focus on oral mucositis as it is a major cause of dose-limiting toxicity. Furthermore, oral candidiasis, viral infections, and xerostomia will be discussed. Conclusions: preventing complications is significantly more important than treating them. All patients beginning systemic anticancer treatment should undergo a thorough oral examination and get appropriate prophylaxis.

Oral manifestations in patients diagnosed with psoriasis: A systematic review

AIMS

To identify the main types of oral lesions associated with psoriasis.

METHODS AND RESULTS

It was a systematic review, based on a search performed in the PubMed/Medline, and Scielo databases, and an associated manual search. Descriptors were selected from DeCs/MeSH and the PICOS strategy (population, intervention, comparison, outcomes, and study design) was applied. Randomized clinical trials and retrospective and prospective studies published from 2000 to 2022 were included, according to the PRISMA parameters (Preferred Reporting Items for Systematic Reviews and Meta-Analysis), registered in the PROSPERO platform. The STROBE quality scale (Strengthening the Reporting of Observational studies in Epidemiology) was also used. One hundred fourteen articles were identified using the search strategy, and nine articles were found in the manual search. Of the sixty-six preselected articles, seven were included in the study. Although it was not possible to identify a specific oral lesion associated with psoriasis, there was a greater occurrence of geographic tongue, fissured tongue, and Candida sp. infection CONCLUSION: Evidence shows that although patients with psoriasis may exhibit lesions in the oral mucosa, they are not specific to this condition. Further epidemiological studies are needed to address the association of psoriasis with possible changes in the oral mucosa.

Cross-kingdom interaction between Candida albicans and oral bacteria

Candida albicans is a symbiotic fungus that commonly colonizes on oral mucosal surfaces and mainly affects immuno-compromised individuals. Polymicrobial interactions between C. albicans and oral microbes influence the cellular and biochemical composition of the biofilm, contributing to change clinically relevant outcomes of biofilm-related oral diseases, such as pathogenesis, virulence, and drug-resistance. Notably, the symbiotic relationships between C. albicans and oral bacteria have been well-documented in dental caries, oral mucositis, endodontic and periodontal diseases, implant-related infections, and oral cancer. C. albicans interacts with co-existing oral bacteria through physical attachment, extracellular signals, and metabolic cross-feeding. This review discusses the bacterial-fungal interactions between C. albicans and different oral bacteria, with a particular focus on the underlying mechanism and its relevance to the development and clinical management of oral diseases.

Distribution of Yeast Species and Risk Factors of Oral Colonization after Oral-Care Education among the Residents of Nursing Homes

Most yeasts causing infections in humans are part of commensal microflora and etiological agents of different infections when hosts become susceptible, usually due to becoming immunocompromised. The colonization of potentially pathogenic microbes in the oral cavity is increased by poor oral hygiene. This follow-up survey was conducted approximately two months after providing information on proper oral care at 10 nursing homes in Taiwan. Among the 117 of 165 residents colonized by yeasts, 67 were colonized by more than one yeast species. A total of 231 isolates comprising eight fungal genera and 25 species were identified. Candida albicans (44.6%) was the dominant species, followed by Candida glabrata (17.7%), Candida parapsilosis (8.7%), Candida tropicalis (7.8%), and Candida pararugosa (7.3%). Residents having a yeast colony-forming unit >10 (OR, 8.897; 95% CI 2.972−26.634; p < 0.001) or using a wheelchair (OR, 4.682; 95% CI 1.599−13.705; p = 0.005) were more likely to be colonized by multiple species. By comparing before and after oral-care education, dry mouth (OR, 3.199; 95% CI 1.448−7.068; p = 0.011) and having heart disease (OR, 2.681; 95% CI 1.068−6.732; p = 0.036) emerged as two independent risk factors for increased density of colonizing yeast.

Oral Candidosis: Pathophysiology and Best Practice for Diagnosis, Classification, and Successful Management

Oral candidosis is the most common fungal infection that frequently occurs in patients debilitated by other diseases or conditions. No candidosis happens without a cause; hence oral candidosis has been branded as a disease of the diseased. Prior research has identified oral candidosis as a mark of systemic diseases, such as hematinic deficiency, diabetes mellitus, leukopenia, HIV/AIDS, malignancies, and carbohydrate-rich diet, drugs, or immunosuppressive conditions. An array of interaction between Candida and the host is dynamic and complex. Candida exhibits multifaceted strategies for growth, proliferation, evasion of host defenses, and survival within the host to induce fungal infection. Oral candidosis presents a variety of clinical forms, including pseudomembranous candidosis, erythematous candidosis, angular cheilitis, median rhomboid glossitis, cheilocandidosis, juxtavermillion candidosis, mucocutaneous candidosis, hyperplastic candidosis, oropharyngeal candidosis, and rare suppurative candidosis. The prognosis is usually favorable, but treatment failure or recurrence is common due to either incorrect diagnosis, missing other pathology, inability to address underlying risk factors, or inaccurate prescription of antifungal agents. In immunocompromised patients, oropharyngeal candidosis can spread to the bloodstream or upper gastrointestinal tract, leading to potentially lethal systemic candidosis. This review therefore describes oral candidosis with regard to its pathophysiology and best practice for diagnosis, practical classification, and successful management.

Candida albicans promotes tooth decay by inducing oral microbial dysbiosis

Candida albicans has been detected in root carious lesions. The current study aimed to explore the action of this fungal species on the microbial ecology and the pathogenesis of root caries. Here, by analyzing C. albicans in supragingival dental plaque collected from root carious lesions and sound root surfaces of root-caries subjects as well as caries-free individuals, we observed significantly increased colonization of C. albicans in root carious lesions. Further in vitro and animal studies showed that C. albicans colonization increased the cariogenicity of oral biofilm by altering its microbial ecology, leading to a polymicrobial biofilm with enhanced acidogenicity, and consequently exacerbated tooth demineralization and carious lesion severity. More importantly, we demonstrated that the cariogenicity-promoting activity of C. albicans was dependent on PHR2. Deletion of PHR2 restored microbial equilibrium and led to a less cariogenic biofilm as demonstrated by in vitro artificial caries model or in vivo root-caries rat model. Our data indicate the critical role of C. albicans infection in the occurrence of root caries. PHR2 is the major factor that determines the ecological impact and caries-promoting activity of C. albicans in a mixed microbial consortium.

Antagonistic effect of isolated and commercially available probiotics on the growth of Candida albicans on acrylic resin denture surfaces

STATEMENT OF PROBLEM

Biofilms can be retained on dental prostheses leading to the development of infections. The indiscriminate use of antifungal drugs can result in the development of microorganisms that are resistant to these antimicrobial agents. Whether probiotics are a suitable alternative for reducing the prevalence of oral candidiasis is unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the influence of 6 different live strains of probiotics and 2 commercially available probiotic supplements used for inhibiting the growth of Candida albicans biofilm in heat-polymerized acrylic resin denture base material and to determine whether biofilm byproducts modify the surface of specimens.

MATERIAL AND METHODS

Biofilms of C. albicans were formed on acrylic resin specimens in the presence of probiotics and quantified by colony-forming units (CFUs), and the surface roughness (Ra) of the specimens was assessed before and after the formation of biofilms. The CFU and roughness data were analyzed by analysis of variance and the Tukey HSD test (α=.05).

RESULTS

A significant decrease in the number (CFU/mL) of C. albicans cells was found when they were cultured with 4 probiotics: B. lactis (P=.045), B. longum (P<.001), L. casei (P<.001), and L. helveticus (P<.001) and with the commercially available probiotic Prolive (P=.05). The Ra of specimens decreased after exposure to different microbial biofilms (P≤.05) except in 3 experimental groups.

CONCLUSIONS

In general, the tested probiotics had an antagonistic effect on the growth of C. albicans, and the surface of acrylic resin was altered after exposure to biofilm byproducts.

Probiotics Reduce the Prevalence of Oral Candida in the Elderly—a Randomized Controlled Trial

Overgrowth of oral yeast is a common problem among the elderly. Probiotic bacteria are known to inhibit the growth of pathogenic microbes. We tested the hypothesis that cheese containing probiotic bacteria can reduce the prevalence of oral Candida. During this 16-week, randomized, double-blind, placebo-controlled study, 276 elderly people consumed daily 50 g of either probiotic (n = 136) or control cheese (n = 140). The primary outcome measure was the prevalence of a high salivary yeast count (≥ 104 cfu/mL) analyzed by the Dentocult® method. The prevalence decreased in the probiotic group from 30% to 21% (32% reduction), and increased in the control group from 28% to 34%. Probiotic intervention reduced the risk of high yeast counts by 75% (OR = 0.25, 95%CI 0.10–0.65, p = 0.004), and the risk of hyposalivation by 56% (OR = 0.44, 95%CI 0.19–1.01, p = 0.05). Thus, probiotic bacteria can be effective in controlling oral Candida and hyposalivation in the elderly.

Effect of Probiotic Bacteria on Oral Candida in Frail Elderly

The aim of this study was to investigate the effect of a daily intake of probiotic lactobacilli on the prevalence and counts of oral Candida in frail elderly patients living in nursing homes. The study had a double-blind randomized placebo-controlled design with 2 parallel arms. The study group consisted of 215 older adults (range, 60 to 102 y) who were enrolled after informed consent. After baseline examination and randomization, the subjects were given 1 lozenge containing 2 strains of the probiotic bacterium Lactobacillus reuteri (DSM 17938 and ATCC PTA 5289) or placebo twice daily (morning and evening). The intervention period was 12 wk, and saliva and plaque samples were collected at baseline and follow-up. The primary end point was prevalence of high Candida counts assessed from chairside tests. Secondary end points were levels of dental plaque and gingival inflammation. The groups were balanced at baseline. The attrition rate to follow-up was 19%. There was a statistically significant reduction in the prevalence of high Candida counts in the probiotic group but not in the placebo group, and the difference was statistically significant in both saliva and plaque (P < 0.05). No significant differences between the groups were noted concerning the levels of supragingival plaque or bleeding on probing. Thus, daily use of probiotic lozenges may reduce the prevalence of high oral Candida counts in frail elderly nursing homes residents (ClinicalTrials.gov NCT02391532).

Effect of Denture-Related Stomatitis Fluconazole Treatment on Oral Candida albicans Susceptibility Profile and Genotypic Variability

Denture-related stomatitis (DRS) is the most common condition affecting removable-denture wearers, and Candida albicans the most frequent pathogenic agent. Systemic antifungal treatment is indicated but recurrences are frequent. The aim of this study was to characterize the oral load, fluconazole susceptibility profile and genotypic variability of oral C. albicans isolates from patients with DRS before (T0), immediately after fluconazole treatment (Tat) and after 6-months follow-up (T6m). Eighteen patients presenting DRS and treated with fluconazole were followed at the Faculty of Dentistry of Oporto University. Seventy C. albicans isolates were obtained and identified using standard cultural and biochemical multi-testing. Fluconazole susceptibility was tested by E-test^®. Microsatellite-primed PCR was performed to assess the genotypic variability of C. albicans isolates. The patients’ mean age was 58.0±3.2 years, and 55.6%/44.4% had total/partial dentures. Before treatment, 22.2%, 44.4% and 33.3% of the patients presented DRS type I, II or III, respectively. Fluconazole treatment healed or improved DRS in 77.8% of the patients, accompanied by an 83.5% reduction in oral C. albicans load. However, after 6-months, oral C. albicans load increased significantly and DRS severity was similar to the one observed before treatment. Moreover, the prevalence of patients presenting fluconazole resistant isolates of C. albicans increased significantly throughout the study: T0-5.6%, Tat-10.0% and T6m-42.9%. A change in the genotypic variability of C. albicans isolates was also verified, being mostly associated to fluconazole susceptibility profile change. In conclusion, fluconazole presents a good short-term DRS treatment efficiency, but may be associated to a long-term emergence of C. albicans fluconazole resistance.

Anti-fungal resistance in candida isolated from oral and diaper rash candidiasis in neonates

The purpose of the present study is to evaluate the sensitivity of Candida species isolated from oral candidiasis and diaper dermatitis infections in children. The children referring to private and public clinics in Ilam, Iran were exmined for oral candidiasis and diaper dermatitis. In this study, 248 oral candidiasis and diaper dermatitis samples were collected and cultured.Candida species were identified by using standard methods. Resistance and sensitivity to amphotericin B, nystatin, ketoconazole, fluconazole, itraconazole, clotrimazole, and posaconazole were determined using the CLSI M44-A standard disk diffusion method. From the 248 studied samples, 149 were positive for Candida, among which the Candida albicans was the most prevalent (64.4%). The resistance of different Candida species to nystatin, itraconazole, fluconazole, ketoconazole, clotrimazole, voriconazole, and posaconazole were 4, 43, 34.2, 34.9, 21.5, 6, and 6.7%, respectively. No resistance to amphotericin B was observed. Considering rather low resistance to nystatin, this drug is the best choice for oral candidiasis and diaper dermatitis.

A multispecies probiotic reduces oral Candida colonization in denture wearers

PURPOSE

The prevalence of Candida infections has been rising with an increasingly aging population and a larger population of immunocompromised individuals. The use of probiotics may be an alternative approach to antifungal agents in the prevention and treatment of oral candidiasis. This study aimed to evaluate the short-term effect of probiotics in reducing the infection level of oral Candida in candidiasis-asymptomatic elderly denture wearers.

MATERIALS AND METHODS

In a double-blind randomized study, 59 denture wearers harboring Candida spp. in the oral cavity with no clinical symptoms were allocated into two groups: probiotic and placebo. All patients were instructed to clean the denture daily. The probiotic group poured a capsule containing lyophilized Lactobacillus rhamnosus HS111, Lactobacillus acidophillus HS101, and Bifidobacterium bifidum daily on the palatal surface of the maxillary denture, whereas the placebo group was submitted to the same regimen using placebo capsules. Candida spp. infection levels were evaluated in palate mucosa samples obtained before and after a 5-week experimental period.

RESULTS

All patients harbored Candida in the palate mucosa at baseline. Fifty-five individuals completed the experimental period. The detection rate of Candida spp. was 92.0% in the placebo group after the experimental period, whereas it was reduced to 16.7% in the probiotic group. The reduction promoted by the probiotic regimen was independent of baseline characteristics such as Candida infection level and colonizing species, age of denture, and other variables.

CONCLUSION

The probiotic product was effective in reducing the colonization of the oral cavity with Candida in candidiasis-asymptomatic elderly denture wearers, suggesting that this multispecies probiotic could be used to prevent oral candidiasis.

CLINICAL IMPLICATIONS

Colonization of oral surfaces by Candida is considered a risk factor for invasive fungal infections. The use of a product with L. rhamnosus, L. acidophilus, and B. bifidum may represent an alternative treatment for reduction of Candida infections in elderly denture wearers.

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.

Fungal Infections

Older adults are at increased risk of developing opportunistic fungal infections because organ transplantation, intensive cancer chemotherapy regimens, and anti-tumor necrosis factor agents are now used more commonly, and because admission to an intensive care unit, which carries many risk factors for fungal infection, has become commonplace in this group.

Candida species are the most common cause of opportunistic fungal infections, and bloodstream infections are usually treated with fluconazole or an echinocandin antifungal agent.

Invasive mold infections are mostly caused by Aspergillus species; in older adults, they cause primarily pulmonary and sinus infections, and they are associated with a high mortality rate.

The endemic fungi, Histoplasma capsulatum, Coccidioides species, and Blastomyces dermatitidis, cause infection when the mold form is dispersed and inhaled from the environment in those specific areas of the country in which these organisms flourish.

Amphotericin B is used for initial treatment of severe histoplasmosis, coccidioi­domycosis, and blastomycosis; itraconazole is the therapy of choice for most mild to moderate infections due to these endemic mycoses.

Oral candidiasis and nutritional deficiencies in elderly hospitalised patients

The prevalence of oral candidiasis and its association with malnutrition in terms of protein–energy malnutrition and mineral and vitamin depletion were evaluated in ninety-seven hospitalised older adults aged 82·1 (SD 8·6) years. Patients underwent a complete oral examination with microbiological investigation on admission to our geriatric rehabilitation unit. Patients were assessed nutritionally by evaluation of dietary intake and measurement of anthropometric variables, serum nutritional proteins, ferritin, Zn, folate, vitamins B12 and C. The prevalence of oral candidiasis was 37% (n 36); the proportion of patients with BMI <20 kg/m2 was 32% (n 31). The nutritional status of the population was studied by comparing two groups defined according to the absence (group I; n 61) or presence (group II; n 36) of oral candidiasis. The two groups did not differ on the basis of BMI and mid-arm circumference. However, group II had a smaller leg circumference, lower daily energy and protein intakes, lower albumin and transthyretin levels. Patients successfully treated with fluconazole increased their intake on day 30. The proportion of patients with hypozincaemia (<12·5 μmol/l) and vitamin C deficiency (<0·7 mg/l) was higher in group II. Treatment with antibiotics, poor oral hygiene, denture wearing, and vitamin C deficiency appeared as the most significant independent risk factors associated with oral candidiasis. The present findings show that oral candidiasis appears to be related to malnutrition and results in mucosal lesions that have a negative impact on energy intake, which may subsequently worsen nutritional status.

Predictive value of oral colonization by Candida yeasts for the onset of a nosocomial infection in elderly hospitalized patients

The incidence of nosocomial yeast infections has increased markedly in recent decades, especially among the elderly. The present study was therefore initiated not only to determine the predictive value of oral colonization by yeasts for the onset of a nosocomial Candida infection in elderly hospitalized patients (>65 years), but also to clarify the factors that promote infection and to establish a relationship between the intensity of oral carriage and the onset of yeast infection. During this prospective cohort study, 256 patients (156 women and 100 men with a mean age of 83±8 years) were surveyed for yeast colonization or infection. Samples were collected every 4 days from day 0 to day 16 from four sites in the mouth, and intrinsic and extrinsic factors that might promote infection were recorded for each patient. Pulsed field gel electrophoresis was performed on Candida albicans isolates from all infected patients. Poor nutritional status was observed in 81 % of the patients and hyposalivation in 41 %. The colonization level was 67 % on day 0 (59 % C. albicans) and a heavy carriage of yeasts (>50 c.f.u.) was observed for 51 % of the patients. The incidence of nosocomial colonization reached 6·9 % on day 4 (6·1 % on day 8 and 2·7 % on day 12), and that of nosocomial infection was 3·7 % on day 4 (6·8 % on day 8, 11·3 % on day 12 and 19·2 % on day 16). Of the 35 patients infected, 57 % were suffering from oral candidiasis. The principal risk factors for colonization were a dental prosthesis, poor oral hygiene and the use of antibiotics. The risk factors for infection, in addition to those already mentioned for colonization, were endocrine disease, poor nutritional status, prolonged hospitalization and high colony counts. Genotyping revealed person-to-person transmission in two patients. Thus, this study demonstrates a significant association between oral colonization and the onset of yeast infections in elderly hospitalized patients. Therefore, oral samples should be collected at admission and antifungal treatment should be administered in cases of colonization, especially in patients presenting a heavy carriage of yeasts. Genotyping of the strains confirmed the possibility of person-to-person transmission.

Radiotherapy-induced salivary dysfunction

Dry mouth (xerostomia) is one of the most common complaints following radiation therapy (RT) for head and neck cancers. Notably, RT causes irreparable damage to salivary glands that increases the risk for severe and long-term oral and pharyngeal disorders. Several strategies in the treatment of head and neck cancers have been developed to prevent RT-induced salivary dysfunction while providing definitive oncologic therapy. These include salivary-sparing RT; cytoprotectants (such as amifostine); combination therapy of high-dose-rate intraoperative RT, external beam RT, plus a cytoprotectant; salivary gland surgical transfer; and gene therapy. Future research that incorporates biologic, pharmacologic, and technologic advancements that optimize therapeutic ratios and minimizes adverse oral sequelae is warranted.

Clinical and microbiological efficacy of chlorine dioxide in the management of chronic atrophic candidiasis: an open study

OBJECTIVE

To assess the clinical and microbiological efficacy of chlorine dioxide (ClO2) as a topical antiseptic for the treatment of chronic atrophic candidiasis in geriatric patients.

PARTICIPANTS

Thirty patients with chronic atrophic candidiasis.

METHODS

Patients were instructed to rinse the mouth with 0.8% ClO2 mouth rinse (DioxiDent) twice daily for one minute and to soak their dentures overnight in the ClO2 for 10 days. Patients were evaluated both clinically and microbiologically at baseline and after 10 days, and any significant side effects were recorded. The clinical appearance of the oral soft tissues was scored on a scale of 0-3 (0 indicating no clinical signs, 1 indicating involvement of < 25% of the palatal mucosa, 2 indicating involvement of 25-50% of the palatal mucosa, and 3 indicating marked erythema involving > 50% of the palatal mucosa). Microbiological testing was undertaken to determine the number of colony forming units (CFUs) of Candida albicans.

RESULTS

ClO2 significantly improved the clinical appearance and microbial count (p < 0.001) after treatment, without significant side effects. Results showed marked improvement in the clinical appearance of the tissues after 10 days, with total resolution in the majority of cases. The total CFU/ml ranged from 15,000-53,000 at baseline and was reduced to < or = 500 after 10 days of treatment (p < 0.001). The mean clinical score was 2.50 at baseline, and was reduced to 0.17 after 10 days of treatment (p < 0.001).

CONCLUSIONS

Within the limitations of this pilot study, the effectiveness of topical chlorine dioxide (0.8%) in the management of chronic atrophic candidiasis was demonstrated. ClO2 provided a safe and clinically effective option in the management of chronic atrophic candidiasis.

Oral candidiasis

Oral candidiasis is a common opportunistic infection of the oral cavity caused by an overgrowth of Candida species, the commonest being Candida albicans. The incidence varies depending on age and certain predisposing factors. There are three broad groupings consisting of acute candidiasis, chronic candidiasis, and angular cheilitis. Risk factors include impaired salivary gland function, drugs, dentures, high carbohydrate diet, and extremes of life, smoking, diabetes mellitus, Cushing's syndrome, malignancies, and immunosuppressive conditions. Management involves taking a history, an examination, and appropriate antifungal treatment with a few requiring samples to be taken for laboratory analysis. In certain high risk groups antifungal prophylaxis reduces the incidence and severity of infections. The prognosis is good in the great majority of cases.

Xerostomia and the geriatric patient

Saliva is essential for the preservation of oral-pharyngeal health, and disorders of salivary physiology are associated with numerous oral and pharyngeal problems, particularly in older people. Although salivary function is remarkably intact in healthy aging, medical problems, medications, and head and neck radiotherapy can cause salivary dysfunction and complaints of xerostomia among older people. Sjögren's syndrome, an autoimmune exocrinopathy, is the most common medical disease associated with salivary dysfunction. Medications with anticholinergic side effects will impair salivary output, and head and neck radiotherapy for cancer will cause permanent destruction of salivary glands. Treatments for salivary problems are based upon establishing a diagnosis, protecting oral and pharyngeal health, stimulating remaining glands, and replacing lost salivary fluids.

Regulation of Candida albicans growth and adhesion by saliva

To examine the local regulation of oral Candida albicans growth, we examined non-stimulated and stimulated salivary flow rates (SFRs) and the C. albicans growth and adhesion inhibitory activities of saliva in 60 patients with oral candidiasis (divided into two groups: 25 patients with oral candidiasis only (group OC) and 35 patients with oral candidiasis and systemic diseases (group CS)) and 30 healthy control subjects. Both non-stimulated and stimulated SFRs in patients, especially in group CS; were decreased in comparison with those in the healthy control subjects. The levels of secretory immunoglobulin A (sIgA) in group OC and group CS and the lactoferrin level in group CS were decreased as compared with those in control individuals, although there were no differences in transferrin and total secretory component (SC) levels between the three groups. The secretion amounts (microg/min) of these proteins were statistically significantly decreased in the patients, especially in group CS. Saliva from the patients showed a lesser inhibitory effect on C. albicans growth and adhesion to HeLa cells than did saliva from the control subjects. In addition, polymorphonuclear leukocytes (PMNs) in patients' saliva generated smaller amounts of superoxide than did those in control subjects' saliva, and phagocytic and C. albicans killing activities were suppressed in the patients. These results indicate that the decreases in SFR, secretion of antimicrobial proteins in saliva, and salivary PMN activity are risk factors for oral candidiasis associated with aging and systemic diseases.

Oral colonization by Candida albicans

Candida albicans is a commensal yeast normally present in small numbers in the oral flora of a large proportion of humans. Colonization of the oral cavity by C. albicans involves the acquisition and maintenance of a stable yeast population. Micro-organisms are continually being removed from the oral cavity by host clearance mechanisms, and so, in order to survive and inhabit this eco-system, C. albicans cells have to adhere and replicate. The oral cavity presents many niches for C. albicans colonization, and the yeast is able to adhere to a plethora of ligands. These include epithelial and bacterial cell-surface molecules, extracellular matrix proteins, and dental acrylic. In addition, saliva molecules, including basic proline-rich proteins, adsorbed to many oral surfaces promote C. albicans adherence. Several adhesins present in the C. albicans cell wall have now been partially characterized. Adherence involves lectin, protein-protein, and hydrophobic interactions. As C. albicans cells evade host defenses and colonize new environments by penetrating tissues, they are exposed to new adherence receptors and respond by expressing alternative adhesins. The relatively small number of commensal Candida cells in the oral flora raises the possibility that strategies can be devised to prevent oral colonization and infection. However, the variety of oral niches and the complex adherence mechanisms of the yeast mean that such a goal will remain elusive until more is known about the contribution of each mechanism to colonization.