Models Hosts for the Study of Oral Candidiasis

Oral candidiasis is an opportunistic infection caused by yeast of the Candida genus, primarily Candida albicans. It is generally associated with predisposing factors such as the use of immunosuppressive agents, antibiotics, prostheses, and xerostomia. The development of research in animal models is extremely important for understanding the nature of the fungal pathogenicity, host interactions, and treatment of oral mucosa! Candida infections. Many oral candidiasis models in rats and mice have been developed with antibiotic administration, induction of xerostomia, treatment with immunosuppressive agents, or the use of germ-free animals, and all these models has both benefits and limitations. Over the past decade, invertebrate model hosts, including Galleria mellonella, Caenorhanditis elegans, and Drosophila melanogaster, have been used for the study of Candida pathogenesis. These invertebrate systems offer a number of advantages over mammalian vertebrate models, predominantly because they allow the study of strain collections without the ethical considerations associated with studies in mammals. Thus, the invertebrate models may be useful to understanding of pathogenicity of Candida isolates from the oral cavity, interactions of oral microorganisms, and study of new antifungal compounds for oral candidiasis.

Photodynamic therapy of oral candidiasis hi hiv-positive patients

The conventional treatments for Candidiasis include therapies that promote serious side effects to patients. Recent research indicates the use of red emission laser associated with a blue photosensitizer as a current method for microbial reduction. This study aimed to evaluate the effectiveness of Photodynamic Therapy in the treatment of oral candidiasis in HIV patients. The response to treatment by the photodynamic therapy has been demonstrated successfully in 100% of the total sample, as in the 7th and 21st days, confirmed he complete absence of clinical and cytological lesions. This therapy is enhanced by its easy applicability and no adverse side effects making it an alternative method of effective recommended treatment.

Curcumin-mediated photodynamic inactivation of Candida albicans in a murine model of oral candidiasis

In vitro investigations of curcumin-mediated photodynamic therapy (PDT) are encouraging, but there is a lack of reliable in vivo evidence of its efficacy. This study describes the photoinactivation of Candida albicans in a murine model of oral candidiasis, using curcumin as a photosensitizer. Forty immunosuppressed mice were orally inoculated with C. albicans and after five days, they received topical curcumin (20, 40 and 80 μM) and illumination with LED light. The use of curcumin or light alone were also investigated. Positive control animals did not receive any treatment and negative control animals were not inoculated with C. albicans. The number of surviving yeast cells was determined and analyzed by ANOVA and Tukey's post-hoc test (α = 0.05). Histological evaluation of the presence of yeast and inflammatory reaction was also conducted. All exposures to curcumin with LED light caused a significant reduction in C. albicans viability after PDT, but the use of 80 μM curcumin associated with light was able to induce the highest log10 reduction in colony counts (4 logs). It was concluded that curcumin-mediated PDT proved to be effective for in vivo inactivation of C. albicans without harming the host tissue of mice. © 2013 ISHAM.

Recent mouse and rat methods for the study of experimental oral candidiasis

The Candida genus expresses virulence factors that, when combined with immunosuppression and other risk factors, can cause different manifestations of oral candidiasis. The treatment of mucosal infections caused by Candida and the elucidation of the disease process have proven challenging. Therefore, the study of experimentally induced oral candidiasis in rats and mice is useful to clarify the etiopathology of this condition, improve diagnosis, and search for new therapeutic options because the disease process in these animals is similar to that of human candidiasis lesions. Here, we describe and discuss new studies involving rat and mouse models of oral candidiasis with respect to methods for inducing experimental infection, methods for evaluating the development of experimental candidiasis, and new treatment strategies for oral candidiasis. © 2013 Landes Bioscience.

Enzymatic activity profile of a Brazilian culture collection of Candida albicans isolated from diabetics and non-diabetics with oral candidiasis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

In vitro evaluation of the enzymatic activity profile of non-albicans Candida species isolated from patients with oral candidiasis with or without diabetes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Essential oil of Melaleuca alternifolia for the treatment of oral candidiasis induced in an immunosuppressed mouse model

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Oral candidiasis mimicking an oral squamous cell carcinoma: report of a case

Oral candidiasis is a significant problem in immune-compromised patients. The most common forms of mucosal candidiasis are oropharyngeal, oesophageal and vaginal, and more than 90% of HIV positive persons will manifest at least one episode of oropharyngeal candidiasis. Local and systemic factors such as uninterrupted daily use of a prosthesis by patients, smoking habit, as well as high glucose intake may contribute to the development of the lesion. The aim of this article is to report an uncommon case of oral candidiasis presenting an aggressive clinical behaviour in a 64-year-old male patient, with a significant smoking habit and a medical history of non-controlled diabetes. The lesion affected the hard and soft palate of the right side, revealing erythematous and ulcerated areas, elevated borders and central portions resembling necrosis, mimicking the clinical features of oral squamous cell carcinoma. However, the correct diagnosis of oral candidiasis was obtained after histopathological and cytological examinations and the patient was easily treated with traditional antifungal drugs and correction of his glucose levels.

Antimicrobial Photodynamic Therapy in the Treatment of Oral Candidiasis in HIV-Infected Patients

Objective: Antimicrobial photodynamic therapy (aPDT) has been used to combat local infections, and it consists of the combination of a photosensitizer, a light source, and reactive oxygen species (ROS) to kill microbial cells. In this study, we evaluated the effectiveness of aPDT in the treatment of candidiasis in HIV-infected patients. Methods: Twenty-one patients were divided into three groups. Control group (CG) was treated with the conventional medication for candidiasis (fluconazole 100 mg/day during 14 days). Laser group (LG) was subjected to low-level laser therapy (LLLT), wavelength 660 nm, power of 30 mW, and fluence of 7.5 J/cm(2), in contact with mucosa during 10 sec on the affected point. An aPDT group (aPDTG) was treated with aPDT, that is, combination of a low-power laser and methylene blue 450 mu g/mL. Pre-irradiation time was 1 min. Parameters of irradiation were the same ones as for the LG, and patients were single irradiated. Patients were clinically evaluated and culture analysis was performed before, immediately after, and 7, 15, and 30 days after the treatment. Results: Our results showed that fluconazole was effective; however, it did not prevent the return of the candidiasis in short-term. LLLT per se did not show any reduction on Candida spp. aPDT eradicated 100% of the colonies of this fungus and the patients did not show recurrence of candidiasis up to 30 days after the irradiation. Conclusions: These findings suggest that aPDT is a potential approach to oral candidiasis treatment in HIV-infected patients.

Distinct roles for interleukin-12p40 and tumour necrosis factor in resistance to oral candidiasis defined by gene-targeting

Cell-mediated immunity is important for anti-Candida host defence in mucosal tissues. In this study we used cytokine-specific gene knockout mice to investigate the requirement for T helper type 1 (Th1) and Th2 cytokines in recovery from oral candidiasis. Knockout mice used in this study included interleukin-4 (IL-4), IL-10, IL-12p40, interferon-gamma (IFN-gamma), and tumour necrosis factor (TNF). The mice were challenged either orally or systemically with Candida albicans yeasts, and levels of colonization were determined. IL-12p40 knockout mice developed chronic oropharyngeal candidiasis, but were not more susceptible to systemic challenge. On the other hand, TNF knockout mice displayed increased susceptibility to both oral and systemic challenge, but only in the acute stages of infection. TNF apparently has a protective effect in the acute stages of both oral and systemic candidiasis, whereas IL-12p40 is essential for recovery from oral but not systemic candidiasis. The role of IL-12p40, and its relation to T-cell-mediated responses remain to be determined.

Invasive candidiasis and oral manifestations in premature newborns

Objective: To investigate prevalence of invasive candidiasis in a Neonatal Intensive Care Unit and to evaluate oral diseases and Candida spp. colonization in low birth weight preterm newborns. Methods: A descriptive epidemiological study performed in two stages. First, prevalence of candidiasis was analyzed in a database of 295 preterm patients admitted to hospital for over 10 days and birth weight less than 2,000g. In the second stage, oral changes and Candida spp. colonization were assessed in 65 patients weighing less than 2,000g, up to 4 week-old, hospitalized for over 10 days and presenting oral abnormalities compatible with fungal lesions. Swab samples were collected in the mouth to identify fungi. Results: Prevalence of candidiasis was 5.4% in the database analyzed. It correlated with prolonged hospital length of stay (p<0.001), in average, 31 days, and 85% risk of developing infection in the first 25 days. It correlated with low birth weight (p<0.001), with mean of 1,140g. The most frequent alterations were white soft plaques, detachable, in oral mucosa and tongue. Intense oral colonization by Candida spp was observed (80%). Conclusions: The frequency of invasive candidiasis was low and correlated with low birth weight and prolonged hospital stay. The most common oral changes were white plaques compatible with pseudomembranous candidiasis and colonization by Candida spp. was above average.