Quantitative evaluation of tissue invasion by wild type, hyphal and SAP mutants of Candida albicans, and non-albicans Candida species in reconstituted human oral epithelium

BACKGROUND: Oral candidiasis is a common problem in compromised patients. Although several non-albicans Candida species have emerged as pathogens the majority of candidal infections are caused by Candida albicans. Morphogenesis from the blastospore to filamentous phase, and production of secretory aspartyl proteinases (SAP) are two major virulence attributes of these opportunistic yeast. Histopathology of oral candidiasis is characterized by fungal invasion of the superficial epithelium although the invasive potentials of different Candida species vary. Computerized image analysis systems (IAS) utilizing immunohistochemistry have been successfully employed for quantification of such histopathological features. The purpose of this study was to evaluate quantitatively the in vitro invasive potential of C. albicans and its hyphal and SAP mutants, and five other non-albicans Candida species using a computerized IAS. METHODS: In vitro human oral candidiasis was produced using five wild type and one reference C. albicans isolates, hyphal and SAP mutants of C. albicans SC 5314, and one wild type and one reference isolate each of C. tropicalis, C. dubliniensis, C. glabrata, C. parapsilosis and C. krusei in a reconstituted human oral epithelium (RHOE) model. The infected tissues were examined histologically at 12, 24 and 48 h. Invading fungal elements were visualized by periodic acid-Schiff (PAS) staining and quantitatively evaluated as a percentage of total tissue invasive area, using a computerized IAS. RESULTS: All C. albicans isolates including hyphal mutant cph1/cph1 and SAP mutants; sap 1-3, sap 4-6 produced hyphae and differentially (P < 0.05) invaded the tissue over 48 h. The invasive potential of hyphal mutant cph1/cph1 and SAP mutants (sap 1-3, sap 4-6) were similar to the parent wild-type isolate at 12 h although after 24 h their invasion was dissimilar (P < 0.05). Non-albicans Candida species and hyphal mutants; efg1/efg1, efg1/efg1 cph1/cph1 were all non-invasive. CONCLUSIONS: RHOE model in combination with computerized image analysis permits for the first time, the assessment of invasive potential of Candida species in a quantitative manner. The differential tissue invasive patterns of various C. albicans isolates, their mutants and other Candida species are also described.     

Irradiation‐induced oral candidiasis in an experimental murine model

The aim of this experiment was to establish a mouse model of irradiation‐induced oral candidiasis and to explore the cellular populations and mechanisms by which the infection is cleared from the oral mucosa. BALB/c mice received irradiation to the head and neck equivalent to 800 Rad using a Cobalt 60 gamma source. Both irradiated and non‐irradiated mice were infected orally with 1×10⁸Candida albicans yeasts. Compared with untreated controls, irradiated animals developed a more severe infection of longer duration, with hyphae penetrating the oral mucosa. Monoclonal antibody depletion of CD4⁺ but not CD8⁺ T cells from the systemic circulation prolonged the infection in irradiated mice, but not in controls. Supernatants of submandibular and superficial cervical lymph node cultures from irradiated animals demonstrated significantly higher titers of interleukin‐12, but similar levels of interferon‐γ compared with controls. Screening for cytokine production by an RNase protection assay detected only macrophage migration inhibition factor in irradiated and non‐irradiated oral tissues from day 8 onwards. The results of this study demonstrate a requirement for CD4⁺ T cells in the recovery from oral candidiasis induced by head and neck irradiation in mice, and are consistent with a role for Th₁‐type cytokines in host resistance.     

Close association between oral Candida species and oral mucosal disorders in patients with xerostomia

Oral Diseases (2012) 18, 667-672 Objective: Heightened interest in oral health has lead to an increase in patients complaining of xerostomia, which is associated with various oral mucosal disorders. In this study, we investigated the relationship between Candida species and oral mucosal disorders in patients with xerostomia. Subjects and Methods: We evaluated whole salivary flow rate and presence of oral mucosal disorders in 48 patients with xerostomia and 15 healthy controls. The number of Candida species was measured as colony-forming units after propagation on selective medium. Identification of Candida at the species level was carried out by polymerase chain reaction and restriction fragment length polymorphism analysis. We then examined the relationship between Candida species and oral mucosal symptoms. Results: Compared with controls, patients with xerostomia exhibited significantly decreased whole salivary flow rate, increased rate of oral mucosal symptoms, and higher numbers of Candida. Salivary flow rate negatively correlated with the number Candida. Among patients with oral candidiasis, Candida albicanswas isolated from the tongue mucosa and Candida glabratawas isolated from the angle of the mouth. Conclusion: These results suggest that particular Candida species are involved in the pathogenesis of oral mucosal disorders in patients with xerostomia.     

Gene targeting demonstrates that inducible nitric oxide synthase is not essential for resistance to oral candidiasis in mice, or for killing of Candida albicans by macrophages in vitro

Introduction:  Oral candidiasis is caused by opportunistic infections with the yeast Candida albicans . Previous studies have demonstrated important roles for innate immunity and T helper type 1-mediated inflammatory reactions in recovery from infection, with macrophages and neutrophils as key effector cells. Both effector cell types use the inducible isoform of nitric oxide synthase (iNOS) to generate candidacidal molecules, but it is not clear whether nitric oxide (NO) is an absolute requirement for candidacidal effector activity.
Methods:  In this study we directly investigated the role of iNOS-derived NO in resistance to murine experimental oral candidiasis, using iNOS knockout mice.
Results:  Knockout mice were no more susceptible to oral candidiasis than wild-type controls. Bone marrow-derived macrophages from the knockout mice killed C. albicans yeasts efficiently in vitro , and were still able to produce nitrites in an iNOS-independent manner, albeit less efficiently than wild-type controls. There were no significant differences in local mucosal production of interleukins 6, 12, 17A, or 23, interferon-γ, or transforming growth factor-β 24 h after oral challenge with C. albicans .
Conclusion:  These data suggest that iNOS-derived NO is not required for resistance to oral candidiasis in vivo , and that bone marrow-derived macrophages may have iNOS-independent means of generating reactive nitrogen species.     

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.     

Irradiation-induced oral candidiasis in an experimental murine model

The aim of this experiment was to establish a mouse model of irradiation-induced oral candidiasis and to explore the cellular populations and mechanisms by which the infection is cleared from the oral mucosa. BALB/c mice received irradiation to the head and neck equivalent to 800 Rad using a Cobalt 60 gamma source. Both irradiated and non-irradiated mice were infected orally with 1 x 10(8) Candida albicans yeasts. Compared with untreated controls, irradiated animals developed a more severe infection of longer duration, with hyphae penetrating the oral mucosa. Monoclonal antibody depletion of CD4+ but not CD8+ T cells from the systemic circulation prolonged the infection in irradiated mice, but not in controls. Supernatants of submandibular and superficial cervical lymph node cultures from irradiated animals demonstrated significantly higher titers of interleukin-12, but similar levels of interferon-gamma compared with controls. Screening for cytokine production by an RNase protection assay detected only macrophage migration inhibition factor in irradiated and non-irradiated oral tissues from day 8 onwards. The results of this study demonstrate a requirement for CD4+ T cells in the recovery from oral candidiasis induced by head and neck irradiation in mice, and are consistent with a role for Th1-type cytokines in host resistance.     

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‐γ (IFN‐γ), 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.     

Asymptomatic oral Candida albicans carriage in HIV-infection: frequency and predisposing factors

Many studies have focused on the epidemiology and pathogenesis of oral candidiasis in HIV infection. Little is known on the incidence and predisposing factors of asymptomatic oral Candida carriage in this setting, obviously an important issue in view of prophylaxis. To address this question. 261 consecutive HIV-infected individuals without clinical evidence of candidiasis were investigated. C. albicans was isolated from cultured oral cavity swabs of 63 subjects (24%). Colonization was significantly more frequent in IV drug users. CDC groups IV. and in subjects with lymphocytopenia. CD4+ cell depletion, or elevated beta-2 microglobulin. These data further suggest that oral candidiasis occurs in HIV infection as a result of C. albicans overgrowth and raise the question of primary antifungal prophylaxis in subjects with low CD4 counts and asymptomatic oral Candida carriage.     

Characterization of Candida parapsilosis infection of an in vitro reconstituted human oral epithelium

Oral candidosis is a common problem in immunocompromised patients, and whilst Candida albicans is regarded as the principal cause of infection, other non‐Candida albicans Candida (NCAC) species are increasingly being recognized as human pathogens. Relatively little is known about the virulence factors associated with NCAC species, and the aim of this study was to use a reconstituted human oral epithelium (RHOE) to examine epithelial infection withCandida parapsilosis. Strains originating from the oral and vaginal mucosa and from the urinary tract were all shown to colonize RHOE in a strain‐dependent manner. Strain differences were found in the colonizing morphology and in the extent of invasion of the RHOE. Low invasion of RHOE was detected for strains after 12 h, whereas extensive tissue damage was evident after 24 h when assessed using histological examination and lactate dehydrogenase activity determination. Tissue damage was reduced in the presence of pepstatin A, although C. parapsilosis invasion of the tissue was not inhibited. Real‐time polymerase chain reaction of secreted aspartyl proteinase (SAP) genes (SAPP1–3) showed that expression was strain dependent, with an increased expression generally occurring for Candida infecting RHOE compared with planktonic equivalents. In summary, C. parapsilosis was not highly invasive of RHOE but did induce significant tissue damage, which could relate to specific SAPgene expression.     

Pseudomembranous oral candidiasis in HIV infection: Ultrastructural findings

A light and electron microscopic investigation of pseudomembranous candidiasis in HIV infection was undertaken as there is little data available on the ultrastructural features of the invasive phase of Candida in this disease. On examination of biopsy specimens of four patients, histopathology revealed the classic features of superficial candidiasis, including hyphal penetration down to the spinous cell layer, parakeratosis, acanthosis and spongiosis of the infected, superficial epithelium. However, in one case, hyphae traversed the entire epithelium and crossed the basal membrane, invading the adjacent connective tissue. Ultrastructural investigations revealed initial hyphal penetration through the intercellular spaces, possibly demonstrating thigmotropism. However, hyphal penetration was not solely confined to intercellular spaces, as some specimens demonstrated hyphal elements traversing both the cytoplasm and the nuclei of the spinous cells. In these areas of the epithelium appressoria-like appendages were often found at the hyphal tip. These phenomena, commonly described in plant fungi, have rarely been described in human material. Pools of desmosomes were seen in the vicinity of the hyphal pathways, implying that the penetration procedure is associated with detachment and congregation of desmosomes, possibly by enzymatic means. Interestingly, the host immune response to fungal invasion appeared to be minimal, as no immune-effector cells were seen closely associated with either the blastospores or the hyphae in any of the tissues examined. Whether the foregoing events are exaggerated by the abortive immune response seen in HIV-infected patients, or common in immunocompetent individuals during candidal invasion of epithelia, needs to be ascertained by further studies.     

白念珠菌口腔黏膜感染小鼠模型的建立及评估

［摘要］ 目的 建立白念珠菌口腔黏膜感染ICR小鼠模型,动态观察口腔黏膜及相应的全身感染情况,并对变化情况进行初步分析。方法 将白念珠菌接种于免疫功能低下小鼠口腔,采用肉眼观察口腔舌背病损改变、口腔内白念珠菌菌量检测、组织病理学等方法评估口腔内黏膜感染情况,检测体重、载菌量（肾、肝、下降结肠内粪便）评估全身感染情况。观察1周,并记录数据。空白对照组为接种生理盐水的免疫功能低下组。结果 ①小鼠接种白念珠菌后第1天口腔白念珠菌菌量较低,随后迅速增长,3~7 d内趋于稳定,稳定于106~107CFU/mL。同时口腔舌背病损也出现类似趋势,第1天未见明显伪膜,3~7 d内可见舌背伪膜存在。②病理切片PAS染色显示接种后3~5 d内白念珠菌形成菌丝侵入并破坏上皮,到接种第7天时,黏膜上皮多见酵母细胞。③小鼠接种白念珠菌后体重逐渐下降。粪便载菌量逐渐上升,第5天达到最大,但肾、肝无白念珠菌感染。空白组未见白念珠菌感染。结论 通过在ICR小鼠口腔内接种白念珠菌可以建立白念珠菌口腔黏膜感染动物模型。接种后白念珠菌感染程度在1周内存在变化。动物实验应根据感染状况选择合适的研究时段。     

Treatment with probiotics in experimental oral colonization by Candida albicans in murine model (DBA/2)

The aim of this study is to evaluate the oral colonization by Candida albicans in experimental murine immunosuppressed DBA/2 and treatment with probiotic bacteria. To achieve these objectives, 152 DBA/2-immunosuppressed mice were orally inoculated with a suspension of C. albicans containing 10(8) viable yeast cells, the animals were treated with nystatin or with the probiotics (Lactobacillus acidophilus and Lactobacillus rhamnosus). Evaluations were performed by Candida count from oral mucosa swabbing. The oral mucosa colonization by C. albicans started at day 1 after inoculation, remained maximal from day 3 until day 7, and then decreased significantly. Probiotics reduced the C. albicans colonization significantly on the oral mucosa in comparison with the untreated animal group. In the group treated with L. rhamnosus, the reduction in yeast colonization was significantly higher compared with that of the group receiving nystatin. Immunosuppressed animal model DBA/2 is a relevant model for experimental Candida oral colonization, and the treatment with probiotics in this model may be an effective alternative to prevent it.     

Oral Candida infection and colonization in solid organ transplant recipients

Introduction:  Oral Candida carriage and infection have been reported to be associated with a greater risk for systemic infection in transplant recipients; however, a systematic analysis of the oral Candida titers and species has not been previously conducted. The objectives of this study were to determine the prevalence of oropharyngeal candidiasis, the oral carrier status, Candida titers and species in this population.
Methods:  Ninety kidney and heart transplant subjects and 72 age-matched healthy controls were included. Swabs from the oral mucosa and a standardized amount of unstimulated saliva were plated on Chromagar™ Candida , and colony-forming units per millilitre were calculated. Initial speciation was based on colony color and was confirmed by standard germ tube, biotyping, or polymerase chain reaction assays.
Results:  Infection with C. albicans was detected in seven transplant subjects and none of the controls. The transplant group had significantly higher oral Candida titers than the control group. There were no statistically significant relationships between the dose or type of immunosuppressants and oral Candida titers or infection. A significantly higher percentage of transplant subjects were colonized by more than one species, compared with control subjects. The most frequent species combination in transplant subjects was C. albicans and C. glabrata . C. glabrata was isolated from 13.5% of transplant carriers and none of the controls.
Conclusions:  Increased oral Candida infection and carriage titers were found in the transplant population. Although the majority of transplant patients were colonized by C. albicans , C. glabrata appears to emerge as the second most prevalent species.     

Effects of triamcinolone acetonide on experimental oral candidiasis in monkeys

abstract – Thirteen adult monkeys (Macaca irus) were infected with Candida albicans by inoculating the microorganisms under an acrylic plate covering the palatal mucosa. Six of the monkeys were treated with the steroid triamcinolone acetonide intramuscularly for 2 weeks before and 2 weeks after inoculation. The palatal mucosa was studied clinically and histologically at weekly or biweekly intervals for up to 5 months after inoculation. The cellular immune response was studied using the direct leukocyte migration test. In the group of seven non-steroid-treated monkeys an acute atrophic candidiasis developed that healed spontaneously in 2—3 weeks. No tissue invasion by Candida was seen in tissue sections, but the inflammation was pronounced. Migration inhibition was significant up to 5 months after infection. In the group of six steroid-treated monkeys an acute pseudomembranous candidiasis was induced that showed retarded healing, tissue invasion by Candida, and enhanced yeast proliferation. Inflammation was only slight and the peripheral blood leukocytes were not inhibited in their migration by Candida antigen. The study has shown that systemic treatment with the steroid, triamcinolone acetonide, potentiate oral Candida infections, probably by suppressing both non-specific inflammatory responses and cellular immunity.     

Prevalence and antifungal susceptibility profiles of Candida glabrata,Candida parapsilosis and their close-related species in oral candidiasis

ObjectiveTo evaluate the importance of Candida glabrata, Candida parapsilosis and their close-related species, Candida bracarensis, Candida nivariensis, Candida metapsilosis and Candida orthopsilosis in patients with oral candidiasis and, to determine the in vitro activities of antifungal drugs currently used for the treatment.MethodsOne hundred fourteen isolates of C. glabrata and 97 of C. parapsilosis, previously identified by conventional mycological methods, were analysed by molecular techniques. In vitro antifungal susceptibility to fluconazole, itraconazole, miconazole, and nystatin was evaluated by CLSI M44-A2 disk diffusion test, and by CLSI M27-A3 microdilution for fluconazole.ResultsAll C. glabrata isolates were identified as C. glabrata sensu stricto, 93 out of 97 C. parapsilosis isolates as C. parapsilosis sensu stricto, three as C. orthopsilosis and one as C. metapsilosis. Candida glabrata was mainly isolated in mixed cultures but C. parapsilosis complex was more frequent in pure culture. Candida metapsilosis and C. orthopsilosis were isolated as pure culture and both species were susceptible to all antifungal agents tested. Most C. glabrata isolates were susceptible to miconazole and nystatin, but resistant to fluconazole and itraconazole. Azole cross resistance was also observed. Candida parapsilosis isolates were susceptible to fluconazole although azole cross resistance to miconazole and itraconazole was observed.ConclusionThis study highlights the importance of accurate identification and antifungal susceptibility testing of oral Candida isolates in order to have an in-depth understanding of the role of C. glabrata and C. parapsilosis in oral candidiasis.     

An ultrastructural and a cytochemical study of candidal invasion of reconstituted human oral epithelium

BACKGROUND: Opportunistic yeast, Candida albicans causes superficial and systemic mycoses in compromised patients. Adhesion to host tissues, morphogenesis and extracellular phospholipases (PL) are thought to contribute to its virulence. The nature of numerous host-parasite interactions at the invasive phase of oral candidiasis is not fully understood. Hence in this study, we explore the ultrastructural features of oral candidiasis using a tissue culture model based on reconstituted human oral epithelium (RHOE). METHODS: Reconstituted human oral epithelium (Skinethic Laboratory, Nice, France) was inoculated with C. albicans SC5314 and incubated up to 48 h. The infected tissue was harvested at 12, 24 and 48 h and examined using light, scanning (SEM) and transmission electron microscopy (TEM). Localized activity of PLs of C. albicans during tissue invasion was also examined using a cytochemical method. RESULTS: Over a period of 48 h C. albicans invaded the RHOE, and histological examination revealed characteristic hallmarks of pathological tissue invasion. Hyphal penetration into the superficial epithelium, particularly at cell junctions, together with features of cellular internalization of yeasts was noted. Phospholipase activity was visible at the tips of hyphae and initial sites of bud formation. Further, SEM studies revealed cavitations on the surface epithelial cells particularly pronounced at the sites of hyphal invasion. Hyphal invasion was seen both at cell surfaces and intercellular cell junctions of the epithelium, the latter resembling thigmotropic behaviour. CONCLUSIONS: Our findings confirm that multiple cellular interactions such as internalization, thigmotropism and extracellular PLs contribute to invasive candidiasis. The RHOE model, described here, appears to be a satisfactory model for the investigation of ultrastructural and histochemical features of invasive candidiasis in humans.     

Oral Candida and Entembacteriaceae in HIV-1 infection: correlation with clinical candidiasis and antimycotic therapy

Oral swabs of 73 HIV-1 infected men (32 under conditions of antimycotic treatment (43,8%)) and 58 controls were cultured for Candida species and Enterobacteriaceae. In Group A without antimycotics, yeasts were isolated from 35/41 swabs (85,4%) (range 2× 10⁶−4 × 10⁶ cfu/ml). In Group B with antimycotics, yeasts were cultured from 27/32 swabs (84,4%) (4×10¹−1 × 10⁶cfu/ml). Oral Enterobacteriaceae (o.e.) were grown from 22% of the swabs of both Group A (2× 10¹−2 × 10⁶cfu/ml) and Group B(4×10⁶−1,6× 10⁶cfu/ml). Growth of o.e. and yeasts (2 × 10⁶−4 × 10⁶cfu/ml). Correlation between yeasts and o. e. were isolated in 14% (2×10¹−6,4 × 10⁶cfu/ml). Correlation between yeasts species to local and systemic treatment deserves further investigations.     

Acquired resistance and persistence of Candida albicans following oral candidiasis in the mouse: a model of the carrier state in humans

In our experimental model of oral candiasis in the CD1 mouse, the primary infection showed reproducible Candida overgrowth kinetics with a peak level on day 5 of the infection. After day 7, the population stabilized at about 300 colony-forming units per excised mucosal tissue. The primary infection triggered an inflammatory response that resolved in under 8 days. At this point, the histological pattern of the mucosa reached a new equilibrium between recruited and resident mononuclear cells. The primary infection also rapidly stimulated cellular immunity, as measured from day 4 by a delayed-type hypersensitivity footpad reaction. Following a second topical challenge with Candida 30 days after the primary infection, the infection was barely delectable and a typical local delayed-type hypersensitivity reaction occurred between 24–72 h. It is proposed that acquired resistance, in conjunction with low-level persistence of Candida in our model, mimics the carrier stale in sensitized humans.     

Prevalence of oral Candida species in leprosy patients from Cambodia and Thailand

BACKGROUND: Leprosy is a chronic bacterial infection which may lead to significant orofacial morbidity. However, reports on the oral mycotic flora of leprosy patients are rare. The aim of the current study was to explore the oral yeast carriage in two groups of leprosy patients. METHODS: 40 Cambodian (seven men, 33 women) and 48 Thai (14 men, 34 women) leprosy patients from Leprosy Rehabilitation Centre Khien Kleang, Phnom Penh, Cambodia and McKean Rehabilitation Center, Chiangmai, Thailand were randomly selected and their demographic data and clinical history were recorded. Tongue and palatal swabs of each patient were collected using sterile Fungi-Quick swabs (Hain Diagnostika, Nehren, Germany) and they were cultured aerobically on Sabouraud's dextrose agar and CHROMAgar (CHROMagar, Paris, France). Yeast were identified by germ tube, chlamydospore production, and assimilation tests (API 20C AUX, Bio-Merieux, Marcy l'Etoile, France) and reconfirmed using APILAB Plus system (Bio-Merieux). RESULTS: Two groups (Cambodian and Thai) had median age of 35 and 64 years. They had been with leprosy for median durations of 17.7 and 38.9 years (P<0.05), respectively. Overall yeast carriage in two cohorts were 80% and 93.75%. Candida albicans had highest carriage rate in either group (65.6%, 44.4%). Candida krusei and C. glabrata existed as second-line colonizers after C. albicans. Candida glabrata carriage was significantly higher in Thai patients (P<0.05). Multispecies carriage was seen in three Cambodian (9.4%) and five Thai (11.5%) patients. CONCLUSIONS: This study indicates high oral yeast carriage in leprosy patients. Candida albicans remains predominant while C. krusei and C. glabrata are second-line oral colonizers. Co-inhabitation of multiple yeast species is also noted in these patients' oral mycotic flora.     

Comparison of a lesion-inducing isolate and a non-lesional isolate of Candida albicans in an immunosuppressed rat model of oral candidiasis

Two distinct strain-related patterns of organism-host interaction on dorsal tongue of immunocompetent rats have been identified for Candida albicans : some isolates induce mucosal lesions, while other isolates penetrate the keratin layer hut do not produce a lesion. This study examined the behavior of each of the two types of isolates in a cyclosporin-immunosuppressed rat model. Groups B (normal) and D (cyclosporin) were orally inoculated with a lesion-inducing isolate of C. albicans. while a non-lesional isolate was given to Groups A (normal) and C (cyclosporin). A typical dorsal tongue lesion developed in 4/18 rats in Group B and in 13/16 in Group D ( p = 0.00267). No significant difference in infection rate between the normal and cyclosporin-treated animals was seen for the non-lesional isolate. The lack of a host inflammatory response associated with the non-lesional isolate may represent an ecologic advantage for the organism.