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Slime production and proteinase activity of Candida species isolated from blood samples and the comparison of these activities with minimum inhibitory concentration values of antifungal agents.

Slime and proteinase activity of 54 strains consisting of 19 Candida parapsilosis and 35 C. albicans strains isolated from blood samples were investigated in this study. Ketoconazole, amphothericin B, and fluconazole susceptibility of Candida species were compared with slime production and proteinase activity of these species. For both Candida species, no correlation was detected between the slime activity and minimum inhibitory concentration (MIC) values of the three antifungal agents. For both Candida species no correlation was detected between the proteinase activity and the MIC values of amphothericin B, and fluconazole however, statistically significant difference, was determined between the proteinase activity and MIC values of ketoconazole (p = 0.007). Slime production was determined by using modified Christensen macrotube method and proteinase activity was measured by the method of Staib. Antifungal susceptibility was determined through the guidelines of National Committee for Laboratory Standards (NCCLS M27-A).

Amphotericin B↗

Respiration, oxidative phosphorylation, and uncoupling protein in Candida albicans.

The respiration, membrane potential (Deltapsi), and oxidative phosphorylation of mitochondria in situ were determined in spheroplasts obtained from Candida albicans control strain ATCC 90028 by lyticase treatment. Mitochondria in situ were able to phosphorylate externally added ADP (200 microM) in the presence of 0.05% BSA. Mitochondria in situ generated and sustained stable mitochondrial Deltapsi respiring on 5 mM NAD-linked substrates, 5 mM succinate, or 100 microM N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride plus 1 mM ascorbate. Rotenone (4 microM) inhibited respiration by 30% and 2 micro M antimycin A or myxothiazole and 1 mM cyanide inhibited it by 85%. Cyanide-insensitive respiration was partially blocked by 2 mM benzohydroxamic acid, suggesting the presence of an alternative oxidase. Candida albicans mitochondria in situ presented a carboxyatractyloside-insensitive increase of Deltapsi induced by 5 mM ATP and 0.5% BSA, and Deltapsi decrease induced by 10 microM linoleic acid, both suggesting the existence of an uncoupling protein. The presence of this protein was subsequently confirmed by immunodetection and respiration experiments with isolated mitochondria. In conclusion, Candida albicans ATCC 90028 possesses an alternative electron transfer chain and alternative oxidase, both absent in animal cells. These pathways can be exceptional targets for the design of new chemotherapeutic agents. Blockage of these respiratory pathways together with inhibition of the uncoupling protein (another potential target for drug design) could lead to increased production of reactive oxygen species, dysfunction of Candida mitochondria, and possibly to oxidative cell death.

Candida albicans↗

Frequency of Trichomonas vaginalis, Candida sp and Gardnerella vaginalis in cervical-vaginal smears in four different decades.

CONTEXT: Vaginitis is one of the principal motives that lead women to seek out an obstetrician or gynecologist. Bacterial vaginosis, candidiasis and trichomoniasis are responsible for 90% of the cases of infectious vaginitis. OBJECTIVE: To verify the frequency of the three main causative agents of vaginitis, Trichomonas vaginalis, Candida sp and Gardnerella vaginalis, in four different decades (1960's, 1970's, 1980's and 1990's). DESIGN: Retrospective. PLACE: A tertiary referral center. PARTICIPANTS: Patients attended to as gynecology and obstetrics outpatients at the Faculdade de Medicina do Triângulo Mineiro during the years 1968, 1978, 1988, 1998, taken as samples of each decade. MAIN MEASUREMENTS: Diagnoses of infection by Trichomonas vaginalis, Candida sp and Gardnerella vaginalis were gathered from 20,356 cervical-vaginal cytology tests on patients attended to as gynecology outpatients at Faculdade de Medicina do Triângulo Mineiro during the years 1968, 1978, 1988, 1998, representing the four decades. The results were grouped according to the age group of the patients: under 20, between 20 and 29, between 30 and 39, between 40 and 49, and 50 or over. Statistical analysis was done via the chi-squared (Mantel-Haentzel) test with a significance level of 5%. RESULTS: In 1968 infections by Trichomonas vaginalis and Candida sp were diagnosed in 10% and 0.5% of the cytology tests and in 1978, 5.1% and 17.3%, respectively (P < 0.0001). Infection by Gardnerella vaginalis could only be evaluated in the latter two decades. In 1988, 19.8% of the women had positive tests for Gardnerella vaginalis, which was the most frequent agent in that year, diminishing in the subsequent decade to 15.9% (P < 0.0001). Candidiasis was the most frequent infection in 1998, detected in 22.5% of the tests (P < 0.0001). In a general manner, all the infections were most frequent among younger patients, especially those aged under 20, in all decades, whereas infections were least frequent among patients aged 50 or over (P < 0.05). CONCLUSION: There was a reduction in the frequency of cervical-vaginal infection by Trichomonas vaginalis and an increase in the frequency of Candida sp over the four decades studied. All the infections were most frequent in patients aged under 20 years.

Adult↗

Candida spp. biotypes in the oral cavity of school children from different socioeconomic categories in Piracicaba-SP, Brazil.

Two hundred and thirty-nine (239) Brazilian children, distributed into five distinct socioeconomic categories (A to E) were studied. Saliva samples were analyzed as to flow rate, pH, buffer capacity and microbial parameters. The results revealed the presence of Candida spp. in 47.3% of the samples. The most commonly isolated species was C. albicans, in all socioeconomic categories, followed by C. tropicalis, C. krusei and C. parapsilosis. There was no statistical correlation between secretion rate, buffer capacity and Candida spp. CFU/ml. The prevalence of Candida spp. did not differ substantially among the groups; however the microorganisms were more detected in categories B and C. Among all species, C. albicans was the most prevalent. Only 5% of the sample presented more than one species--C. albicans associated with C. tropicalis, C. parapsilosis or C. krusei. It was possible to detect a significant correlation between caries indices and the socioeconomic categories. All categories presented increased caries indices; however the studied population was considered of low caries risk. There was no positive correlation between the presence of Candida and caries risk in the analyzed population.

Brazil↗

Biofilms and their role in the resistance of pathogenic Candida to antifungal agents.

Fungal pathogens of the genus Candida form biofilms on catheters and prosthetic devices. These three-dimensional structures composed of yeast and hyphal cells embedded in an extracellular matrix constitute an important pitfall in the management of disseminated Candida infections because of their intrinsic resistance to almost all antifungals in clinical use. Candida biofilms are especially resistant to azoles and amphotericin B but remain sensitive to the newly introduced echinocandins that target cell wall beta-glucan biosynthesis. Antifungal resistance of biofilms results most probably from the conjunction of several mechanisms that act in a time-dependent manner. While drug efflux is likely to contribute to resistance during the early phases of biofilm formation, changes in the sterol composition of membranes might explain the resistance of mature biofilms. The original physiology of mature Candida biofilms is mirrored by specific gene expression patterns that may pinpoint genes important for the acquisition of pleiotropic antifungal resistance.

Animals↗

Candida albicans pneumonia: radiographic appearance.

A retrospective series of patients with pure Candida albicans pulmonary opportunistic infection confirmed at autopsy were examined for any characteristic radiographic pattern. Of the 20 patients examined, eight showed nonlobar, nonsegmental, bilateral disease; the others exhibited unilateral or bilateral lobar or segmental patterns. Cavitation, adenopathy, masslike opacities, or a miliary pattern were not identified. Radiographically these "negative" findings can be useful in distinguishing Candida from other fungal opportunistic infections. Histologic evidence of lung invasion by Candida is necessary for definitive confirmation. The previously described association of Candida infection with certain underlying diseases (leukemia and lymphoma) was again demonstrated.

Adolescent↗

Risk factors for colonization of salivary lactobacilli and Candida in children.

We analyzed the occurrence of salivary lactobacilli and Candida in a sample of 166 children aged 1-4 years (mean, 2.5 years) in relation to possible risk factors for colonization of the microbes. The risk factors examined were sucking habits, feeding habits, symptoms of respiratory infections, and antibiotic therapy at the time of sampling. Lactobacilli occurred in 18% of the children's saliva, and Candida in 24%. In the logistic modeling the variables most strongly associated with the occurrence of lactobacilli were pacifier-sucking (relative risk (RR), 2.9; 95% confidence interval (CI), 1.1-7.0; P = 0.01) and antibiotic therapy (RR, 4.6; CI, 1.2-16.9; P = 0.01). The association between positive Candida test and use of a pacifier was also significant (RR, 4.8; CI, 2.1-10.7; P = 0.0001). The results of the study suggest that the use of a pacifier increases the occurrence of both salivary lactobacilli and Candida. It could therefore be a factor influencing caries susceptibility and activity in children.

Anti-Bacterial Agents↗

Dietary vitamin E supplementation does not inhibit Candida albicans intestinal translocation in rats.

Candida albicans translocation was determined in rats receiving a normal or vitamin E-supplemented and deficient diet submitted to mesenteric ischemia and reperfusion (MIR). The antioxidant effect of vitamin E on lipid peroxidation was also assessed. The animals were divided into six groups submitted to different diets for 30 d. Groups N, NI, NC and NIC were submitted to a normal diet and used as controls, and groups VITE and DEFE received a vitamin E-supplemented and vitamin E-deficient diet, respectively. Groups NIC, VITE and DEFE were submitted to MIR, inoculated with Candida albicans and sacrificed 24 h after the surgical procedure. The antioxidant effect of vitamin E was determined in the liver and gut mucosa using the TBARS method. Candida albicans translocation was assessed in lymph node, liver and kidney specimens. The results showed that lipid peroxidation was lower (p < 0.05) in the vitamin E-supplemented group. However, vitamin E supplementation did not protect the rats against Candida albicans translocation (the translocation in the Group VITE was 100% for lymph nodes).

Animals↗

[Augmentation of anti-Candida activity of neutrophils by macrophages treated with itraconazole].

Effects of itraconazole (ITCZ) on anti-Candida activity of a macrophage (MP)-neutrophil axis were examined in vitro. Murine peritoneal MP, stimulated by an enterococcal preparation FK-23, released tumor necrosis factor a (TNF) into the culture medium in 20 hr-culture period. This level of TNF production by the stimulated MP, which were measured by a bioassay or immunological assay, was heightened by co-stimulation with 0.5 mg/ml of ITCZ. Supernatants obtained from the culture medium of FK-23 and ITCZ-treated MP not only contained about 10 ng/ml of TNF but also had the capacity to enhance anti-Candida activity of murine neutrophils. This enhancement was blocked by pretreatment of the MP-supernatant with anti-TNF antibody. Observation by scanning electron microscope suggested that cell walls of the candida mycelia, the growth of which was inhibited by the neutrophils in the presence of either the MP-supernatant or TNF, sustained similar structural damage. These results suggest that ITCZ augments anti-Candida activity of neutrophils through enhanced production of TNF by MP in vitro.

Animals↗

Isolation of Candida dubliniensis from the oral cavity of an HIV-positive child in Brazil.

Candida dubliniensis is a newly-recognized Candida species and an important infectious pathogen, particularly for HIV-positive patients. >From oral smear samples from the radix linguae of 173 HIV-positive children, we obtained four yeast isolates which took a blue-green color on CHROMagar Candida plate at 37 degrees C for 48 hours from one HIV-positive 3-year-old boy in Brazil. The isolates were difficult to grow on potato dextrose agar plate at 42 degrees C, produced abundant chlamydospores on a cornmeal agar plate with Tween 80, and sprouted germ tubes in saline with horse serum, and the antigenic profile by CANDIDA CHECK test was useless. Carbohydrate assimilation tests by ID32C showed no reference code number in the reference book. The isolates were subjected to molecular biological assay of the DNA sequence of the large-subunit ribosomal DNA region (D1/D2) and randomly amplified polymorphic DNA (RAPD). The DNA sequence agreed with those of standard C. dubliniensis strains, and therefore, the isolates were identified as C. dubliniensis. RAPD band pattern analysis indicated that the clinical isolates might summarize one genotype. Although the child did not present oral lesions, the fungus might be latent for opportunistic infection.

Brazil↗

Protective antigens and mechanisms of anti-Candida immunity.

Life threatening fungal diseases are now frequent in a substantial fraction of the immunocompromised host population. The toxicity and the relative scarcity of efficacious antifungal drugs highlight the need for developing alternative or integrative immunoprophylactic and therapeutic tools; among them the need to develop prophylactic or therapeutic vaccines against candidiasis, a widespread mucosal or deep-seated infection caused primarily by the fungus Candida albicans, are of clear priority. Vaccination is a highly beneficial medical practice, and probably the most cost-effective measure against disease onset and progression. It is based on the use of microbial antigens capable of conferring protection in a susceptible target host. To date, only a handful of Candida albicans antigens have been produced and very few of them have been thoroughly investigated for immunogenicity and protection in experimental models of candidiasis. Thus, approaches to the molecular, biochemical and functional characterization of novel C. albicans encoded molecules are most welcome to improve the perspective of developing in the near future an effective vaccine against C. albicans. Identification of anti-Candida vaccine candidates must take into account the diversity of Candida diseases, the various underlying mechanisms of protection as well as the major immune dysfunctions observed as predisposing factors for disease. Antigens to be considered possible vaccine candidates include members of the aspartyl proteinase (Sap2) family and the 65kDa mannoprotein (MP65) antigen. An additional molecule of C. albicans which has not yet been identified but deserves great consideration as a vaccine candidate is the yeast-killer toxin receptor (KTR). Initial experimental evidence strongly suggests that the above antigens are able to elicit protective immunity against mucosal and/or systemic candidiasis. A series of molecular, biochemical and immunological studies aimed at validating and strengthening this initial evidence are in progress, with the ultimate goal of producing recombinant or natural antigens that can be assessed for their ability to elicit a protective immunity in animal models and the mechanisms whereby protection is achieved, with emphasis on determination of immune correlates of protection.

Animals↗

The presumptive identification of Candida albicans with germ tube induced by high temperature.

For direct identification of Candida albicans from other Candida species, the chlamydospore formation and the mycelial transition induced by high temperature and by sera were examined in 198 Candida isolates. The germ tubes of C. albicans developed early at 30 min in high temperature-induction, but at 60 min in serum-induction. C. albicans generated germ tubes well at concentrations lower than 2 x 10(7) cells/ml, but the germ tube formation was markedly restrained at concentrations higher than 4 x 10(7) cells/ml. In a serum-free, yeast extract-peptone-dextrose (YEPD) medium, C. albicans grew as a yeast form at 30 degrees C and as a mycelial form at 35-42 degrees C. Mycelial development was maximal at 37 degrees C in serum and at 39 degrees C in YEPD. Germ tubes were formed within 30 min in YEPD at 39 degrees C, but after 60 min in serum at 37 degrees C. Our examination showed that the 39 degrees C-induced germ tube formation tests were very reliable (sensitivity 100%, specificity 100%) at discerning C. albicans from other Candida species. These results suggest that the high temperature-induced germ tube formation testing could be a useful identification method of C. albicans in clinical laboratories.

Candida albicans↗

[DNA and RNA random amplification polymorphism in 5-flurocytosine-resistant strains of Candida albicans from revul-vaginal candidasis].

OBJECTIVE: To investigate the DNA genome and RNA expression in 5-flurocytosine-resistant strains of Candida albicans from vaginal candidasis. METHODS: Sixteen strains of Candida albicans were selected from clinically diagnosed revul-vaginal candidasis. Eight 5-flurocytosine-sensitive isolates and 8 resistant isolates were examined by France Media FUNGUS sensitive test. DNA genome was detected with random amplification polymorph DNA. RNA expression was detected with random amplification polymorph RNA method. RESULTS: There were no distinct differences between 5-flurocytosine-sensitive and resistant Candida albicans in DNA genome, while RNA expression showed significant differences between 5-flurocytosine-resistant and sensitive strains. CONCLUSION: Clinical 5-flurocytosine-resistant strains of Candida albicans from revul-vaginal candidasis may be related to phenotype changes.

Adolescent↗

Dendritic cells pulsed with fungal RNA induce protective immunity to Candida albicans in hematopoietic transplantation.

Immature myeloid dendritic cells (DC) phagocytose yeasts and hyphae of the fungus Candida albicans and induce different Th cell responses to the fungus. Ingestion of yeasts activates DC for production of IL-12 and Th1 priming, while ingestion of hyphae induces IL-4 production and Th2 priming. In vivo, generation of antifungal protective immunity is induced upon injection of DC ex vivo pulsed with Candida yeasts but not hyphae. In the present study we sought to determine the functional activity of DC transfected with yeast or hyphal RNA. It was found that DC, from either spleens or bone marrow, transfected with yeast, but not hyphal, RNA 1) express fungal mannoproteins on their surface; 2) undergo functional maturation, as revealed by the up-regulated expression of MHC class II Ags and costimulatory molecules; 3) produce IL-12 but no IL-4; 4) are capable of inducing Th1-dependent antifungal resistance when delivered s.c. in vivo in nontransplanted mice; and 5) provide protection against the fungus in allogeneic bone marrow-transplanted mice, by accelerating the functional recovery of Candida-specific IFN-gamma-producing CD4(+) donor lymphocytes. These results indicate the efficacy of DC pulsed with Candida yeasts or yeast RNA as fungal vaccines and point to the potential use of RNA-transfected DC as anti-infective vaccines in conditions that negate the use of attenuated microorganisms or in the case of poor availability of protective Ags.

Adoptive Transfer↗

Candida tropicalis causing prosthetic valve endocarditis.

The incidence of endocarditis produced by the so-called "opportunists" as a complication of prosthetic valve surgery is progressively increasing in frequency and gradually transforming the clinical picture habitually associated with this disease. Candida endocarditis is an unusual but severe complication caused by Candida albicans or other fungal species. This case and a review of the literature indicate that Candida endocarditis treated with amphotericin B and prosthetic valve replacement may recur months after treatment, and that late recurrent Candida endocarditis, which is difficult to diagnose and treat, may be best prevented by lifelong antifungal suppressive therapy.

Adult↗

[Degranulation of eosinophils by IgG antibody to Candida antigen].

The pathophysiological role of IgG antibody to fungi antigen widely distributed in environment such as Candida albicans in bronchial asthma has not been clarified. Wells of microtiter plate were coated with the extract of Candida albicans and then IgG antibody was immobilized on the wells by incubation with patient's serum. After cultivation of eosinophils on the well, degranulation of eosinophils, as assessed by quantitation of EPX in the supernatant, has been observed. Degranulation was completely abrogated after depletion of IgG in the serum and also decreased by incubation of the cells with anti-CD32 antibody, or anti-CD18 antibody, but not anti-CD23 antibody. Immune complex, which had been prepared by incubation of the extract of Candida albicans with patient's serum, also evoked degranulation of eosinophils. We have examined whether degranulation can be induced by two purified antigens of Candida albicans, i.e., mannan A and acid protease. IgG antibody to acid protease was detected at no or minimal levels in most sera and the antigen did not induce degranulation. On the other hand, mannan A induced degranulation. This observation may be due to response for the presence of IgG antibody to mannan A in the sera. These results suggest that immobilized IgG induced degranulation of eosinophils through Fc gamma RII (CD 32) on eosinophils and mannan A is a major allergen associated with IgG-induced eosinophil degranulation.

Allergens↗

Increased susceptibility of TNF-alpha lymphotoxin-alpha double knockout mice to systemic candidiasis through impaired recruitment of neutrophils and phagocytosis of Candida albicans.

TNF-alpha and lymphotoxin-alpha (LT) are members of the TNF family, and these cytokines play crucial roles in the defense against infection with Candida albicans. The aim of the present study was to investigate the role of endogenous TNF and LT during disseminated candidiasis in TNF-/-LT-/- knockout mice. The TNF- and LT-deficient animals had a significantly increased mortality following C. albicans infection compared with control mice, and this was due to a 10- to 1000-fold increased outgrowth of the yeast in their organs. No differences between TNF-/-LT-/- mice and TNF+/+LT+/+ were observed when mice were rendered neutropenic, suggesting that activation of neutrophils mediates the beneficial effects of endogenous TNF and LT. Histopathology of the organs, combined with neutrophil recruitment experiments, showed a dramatic delay in the neutrophil recruitment at the sites of Candida infection in the TNF-/-LT-/- mice. Moreover, the neutrophils of deficient animals were less potent to phagocytize Candida blastospores than control neutrophils. In contrast, the killing of Candida and the oxygen radical production did not differ between neutrophils of TNF-/-LT-/- and TNF+/+LT+/+ mice. Peak circulating IL-6 was significantly higher in TNF-/-LT-/- mice during infection. Peritoneal macrophages of TNF-/-LT-/- mice did not produce TNF, and synthesized significantly lower amounts of IL-1alpha, IL-1beta, IL-6, and macrophage-inflammatory protein-1alpha than macrophages of TNF+/+LT+/+ animals did. In conclusion, endogenous TNF and/or LT contribute to host resistance to disseminated candidiasis, and their absence in TNF-/-LT-/- mice renders the animals susceptible through impaired recruitment of neutrophils and impaired phagocytosis of C. albicans.

Animals↗

Growth inhibition of Candida albicans by vaginal cells from naïve mice.

Recurrent vulvovaginal candidiasis (RVVC) is a common idiopathic mucosal infection caused by Candida albicans. Current data suggests that local immunity is more important than that in the peripheral circulation for protection against infection. In the present study, anti-Candida innate resistance at the vaginal mucosa was investigated using a murine model. For this, splenic and vaginal cells were assessed for in vitro growth inhibition (GI) of C. albicans and cytotoxicity of natural killer (NK) cell-sensitive tumour targets (YAC-1). As expected, significant GI of C. albicans by splenic cells was mediated predominantly by polymorphonuclear leucocytes (PMNL) at effector to target (E:T) ratios of 100 and 50:1. From the vaginal mucosa, naïve unfractionated, but not nylon wool non-adherent (NWN), cells extracted from whole vaginal tissue showed significant GI of C. albicans at E:T ratios as low as 1:1, but only modest killing of YAC-1 targets at all E:T ratios. Subsequent experiments showed significant GI of C. albicans by vaginal epithelioid-enriched cells and with several epithelial cell lines, but not in supernatants collected from the co-cultures. In contrast, lymphoid cell lines had no anti-Candida activity. These results suggest that anti-Candida activity is present at the vaginal mucosa, but unlike that from the spleen, the vaginal activity appears to be predominantly mediated by epithelial cells.

Animals↗