Pathogenicity determinants of Candida

Candida tropicalis Affects Candida albicans Virulence by Limiting Its Capacity to Adhere to the Host Intestinal Surface, Leading to Decreased Susceptibility to Colitis in Mice

Candida (C.) infections represent a serious health risk for people affected by inflammatory bowel disease. An important fungal virulence factor is the capacity of the fungus to form biofilms on the colonized surface of the host. This research study aimed to determine the effect of a C. tropicalis and C. albicans co-infection on dextran sodium sulfate (DSS)-induced colitis in mice. The colitis severity was evaluated using histology and a colonoscopy. The mice were mono-inoculated with C. albicans or C. tropicalis or co-challenged with both species. The mice were administered 3% DSS to induce acute colitis. The biofilm activity was assessed using (2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl] 2H-tetrazoliumhydroxide (XTT) and dry-weight assays. The abundance of C. albicans in the colon tissues was assessed by immunohistochemistry. The co-challenged mice showed a decreased colitis severity compared to the mono-inoculated mice. The dry-weight assay demonstrated a marked decrease in C. albicans biofilm production in a C. albicans culture incubated with C. tropicalis supernatant. Immunohistochemical staining showed that C. albicans was more abundant in the mucosa of C. albicans mono-inoculated mice compared to the co-inoculated group. These data indicate an antagonistic microbial interaction between the two Candida species, where C. tropicalis may produce molecules capable of limiting the ability of C. albicans to adhere to the host intestinal surface, leading to a reduction in biofilm formation.

Metabolic reconstruction of the human pathogen Candida auris: using a cross-species approach for drug target prediction

Candida auris is an emerging human pathogen, associated with antifungal drug resistance and hospital candidiasis outbreaks. In this work, we present iRV973, the first reconstructed Genome-scale metabolic model (GSMM) for C. auris. The model was manually curated and experimentally validated, being able to accurately predict the specific growth rate of C. auris and the utilization of several sole carbon and nitrogen sources. The model was compared to GSMMs available for other pathogenic Candida species and exploited as a platform for cross-species comparison, aiming the analysis of their metabolic features and the identification of potential new antifungal targets common to the most prevalent pathogenic Candida species. From a metabolic point of view, we were able to identify unique enzymes in C. auris in comparison with other Candida species, which may represent unique metabolic features. Additionally, 50 enzymes were identified as potential drug targets, given their essentiality in conditions mimicking human serum, common to all four different Candida models analysed. These enzymes represent interesting drug targets for antifungal therapy, including some known targets of antifungal agents used in clinical practice, but also new potential drug targets without any human homolog or drug association in Candida species.

A Genome-Scale Metabolic Model for the Human Pathogen Candida Parapsilosis and Early Identification of Putative Novel Antifungal Drug Targets

Candida parapsilosis is an emerging human pathogen whose incidence is rising worldwide, while an increasing number of clinical isolates display resistance to first-line antifungals, demanding alternative therapeutics. Genome-Scale Metabolic Models (GSMMs) have emerged as a powerful in silico tool for understanding pathogenesis due to their systems view of metabolism, but also to their drug target predictive capacity. This study presents the construction of the first validated GSMM for C. parapsilosis—iDC1003—comprising 1003 genes, 1804 reactions, and 1278 metabolites across four compartments and an intercompartment. In silico growth parameters, as well as predicted utilisation of several metabolites as sole carbon or nitrogen sources, were experimentally validated. Finally, iDC1003 was exploited as a platform for predicting 147 essential enzymes in mimicked host conditions, in which 56 are also predicted to be essential in C. albicans and C. glabrata. These promising drug targets include, besides those already used as targets for clinical antifungals, several others that seem to be entirely new and worthy of further scrutiny. The obtained results strengthen the notion that GSMMs are promising platforms for drug target discovery and guide the design of novel antifungal therapies.

Guideline: Vulvovaginal candidosis (AWMF 015/072, level S2k)

Approximately 70-75% of women will have vulvovaginal candidosis (VVC) at least once in their lifetime. In premenopausal, pregnant, asymptomatic and healthy women and women with acute VVC, Candida albicans is the predominant species. The diagnosis of VVC should be based on clinical symptoms and microscopic detection of pseudohyphae. Symptoms alone do not allow reliable differentiation of the causes of vaginitis. In recurrent or complicated cases, diagnostics should involve fungal culture with species identification. Serological determination of antibody titres has no role in VVC. Before the induction of therapy, VVC should always be medically confirmed. Acute VVC can be treated with local imidazoles, polyenes or ciclopirox olamine, using vaginal tablets, ovules or creams. Triazoles can also be prescribed orally, together with antifungal creams, for the treatment of the vulva. Commonly available antimycotics are generally well tolerated, and the different regimens show similarly good results. Antiseptics are potentially effective but act against the physiological vaginal flora. Neither a woman with asymptomatic colonisation nor an asymptomatic sexual partner should be treated. Women with chronic recurrent Candida albicans vulvovaginitis should undergo dose-reducing maintenance therapy with oral triazoles. Unnecessary antimycotic therapies should always be avoided, and non-albicans vaginitis should be treated with alternative antifungal agents. In the last 6 weeks of pregnancy, women should receive antifungal treatment to reduce the risk of vertical transmission, oral thrush and diaper dermatitis of the newborn. Local treatment is preferred during pregnancy.

Throat swabs have no influence on the management of patients with sore throats

BACKGROUND

Throat swabs are neither specific nor sensitive for micro-bacteria causing sore throat symptoms; however, current guidelines suggest they are still useful in some cases.

METHOD

Retrospective and prospective analyses were conducted of throat swabs requested within the months of January 2016 and August 2016, respectively.

RESULTS

The study comprised 247 patients. Fifty-nine (24 per cent) had a positive culture. Forty-six grew group A beta-haemolytic streptococci, with the remainder growing candida (n = 10), coliform (n = 1) and klebsiella (n = 2). There was no significant difference in culture rates between primary or secondary care sources (χ2 = 0.56, p = 0.45). None of the swabs influenced a variation in patient management from local antimicrobial policies. Current practice has an estimated annual financial impact of £3 434 340 on the National Health Service.

CONCLUSION

Throat swabs do not influence the antimicrobial treatment for patients with sore throats, even under current guidelines, and incur unnecessary cost. Current clinical guidelines could be reviewed to reduce the number of throat swabs being conducted unnecessarily.

Genotypes and virulence factors of Candida species isolated from oralcavities of patients with type 2 diabetes mellitus

BACKGROUND/AIM

This study compared the genotypes and virulence factors of Candida species isolated from oral cavities of healthy individuals and patients with diabetes mellitus (DM).

MATERIALS AND METHODS

A total of 142 healthy individuals and 73 diabetic patients participated in this study. Study populations were classified into 4 groups as follows: Group I - Healthy, without caries; Group II - Healthy, with caries; Group III - DM, with caries; Group IV - DM, without caries. Diabetic patients' blood glucose and hemoglobin A1c concentrations were determined. Identification of Candida species was performed with conventional methods. Biofilm production, proteinase, phospholipase, and esterase were analyzed. The genetic diversity of Candida species was established using rep-PCR.

RESULTS

The most isolated species was Candida albicans. There were statistical differences in terms of isolated Candida frequency between healthy subjects and diabetic patients. There was no statistical difference between the virulence factors of groups. Twelve genotypes were determined. While there were statistical differences in aerobe biofilm production, proteinase, and phospholipase activity between genotypes, there were no statistical differences in anaerobe biofilm production and esterase activity between genotypes.

CONCLUSION

Diabetes has no effect on the activities of virulence factors of Candida species. Different genotypes of Candida albicans exhibited different virulence activities.

Guideline: vulvovaginal candidosis (AWMF 015/072), S2k (excluding chronic mucocutaneous candidosis)

The oestrogenised vagina is colonised by Candida species in at least 20% of women; in late pregnancy and in immunosuppressed patients, this increases to at least 30%. In most cases, Candida albicans is involved. Host factors, particularly local defence mechanisms, gene polymorphisms, allergies, serum glucose levels, antibiotics, psycho-social stress and oestrogens influence the risk of candidal vulvovaginitis. Non-albicans species, particularly Candida glabrata, and in rare cases also Saccharomyces cerevisiae, cause less than 10% of all cases of vulvovaginitis with some regional variation; these are generally associated with milder signs and symptoms than normally seen with a C. albicans-associated vaginitis. Typical symptoms include premenstrual itching, burning, redness and odourless discharge. Although itching and redness of the introitus and vagina are typical symptoms, only 35-40% of women reporting genital itching in fact suffer from vulvovaginal candidosis. Medical history, clinical examination and microscopic examination of vaginal content using 400× optical magnification, or preferably phase contrast microscopy, are essential for diagnosis. In clinically and microscopically unclear cases and in chronically recurring cases, a fungal culture for pathogen determination should be performed. In the event of non-C. albicans species, the minimum inhibitory concentration (MIC) should also be determined. Chronic mucocutaneous candidosis, a rarer disorder which can occur in both sexes, has other causes and requires different diagnostic and treatment measures. Treatment with all antimycotic agents on the market (polyenes such as nystatin; imidazoles such as clotrimazole; and many others including ciclopirox olamine) is easy to administer in acute cases and is successful in more than 80% of cases. All vaginal preparations of polyenes, imidazoles and ciclopirox olamine and oral triazoles (fluconazole, itraconazole) are equally effective (Table ); however, oral triazoles should not be administered during pregnancy according to the manufacturers. C. glabrata is not sufficiently sensitive to the usual dosages of antimycotic agents approved for gynaecological use. In other countries, vaginal suppositories of boric acid (600 mg, 1-2 times daily for 14 days) or flucytosine are recommended. Boric acid treatment is not allowed in Germany and flucytosine is not available. Eight hundred-milligram oral fluconazole per day for 2-3 weeks is therefore recommended in Germany. Due to the clinical persistence of C. glabrata despite treatment with high-dose fluconazole, oral posaconazole and, more recently, echinocandins such as micafungin are under discussion; echinocandins are very expensive, are not approved for this indication and are not supported by clinical evidence of their efficacy. In cases of vulvovaginal candidosis, resistance to C. albicans does not play a significant role in the use of polyenes or azoles. Candida krusei is resistant to the triazoles, fluconazole and itraconazole. For this reason, local imidazole, ciclopirox olamine or nystatin should be used. There are no studies to support this recommendation, however. Side effects, toxicity, embryotoxicity and allergies are not clinically significant. Vaginal treatment with clotrimazole in the first trimester of a pregnancy reduces the rate of premature births. Although it is not necessary to treat a vaginal colonisation of Candida in healthy women, vaginal administration of antimycotics is often recommended in the third trimester of pregnancy in Germany to reduce the rate of oral thrush and napkin dermatitis in healthy full-term newborns. Chronic recurrent vulvovaginal candidosis continues to be treated in intervals using suppressive therapy as long as immunological treatments are not available. The relapse rate associated with weekly or monthly oral fluconazole treatment over 6 months is approximately 50% after the conclusion of suppressive therapy according to current studies. Good results have been achieved with a fluconazole regimen using an initial 200 mg fluconazole per day on 3 days in the first week and a dosage-reduced maintenance therapy with 200 mg once a month for 1 year when the patient is free of symptoms and fungal infection (Table ). Future studies should include Candida autovaccination, antibodies to Candida virulence factors and other immunological experiments. Probiotics with appropriate lactobacillus strains should also be examined in future studies on the basis of encouraging initial results. Because of the high rate of false indications, OTC treatment (self-treatment by the patient) should be discouraged.

Epidemiology, Diagnosis, and Therapy of Fungal Infections in Surgery

Over the past decade, the incidence of hospital-acquired bloodstream infections caused byCandidastrains has risen, while the implicated species have changed.Candida tropicalis, Candida parapsilosis, andCandida glabrataall have increased in incidence. Data from the Centers for Disease Control and Prevention reveal that, between 1980 and 1990,Candidaemerged as the sixth most common nosocomial pathogen (7.2.%) and was the fourth most common pathogen in nosocomial bloodstream infections, surpassed only by coagulase-negative staphylococci,Staphylococcus aureus, and enterococci. The incidence of candidemia is dramatically higher in high-risk critical-care units: 25% of cases occur in surgical intensive-care units (ICUs) versus 25% in bone marrow transplantation units, 20% in medical ICUs, 20% in general medical wards, and 10% in oncology-hematology units. Burns and gastrointestinal surgery predispose to nosocomial candidemia. Independent risk factors include prior therapy with multiple antibiotics, isolation ofCandidafrom sites other than blood, and prior hemodialysis. Crude mortality exceeds 55% and is associated with older age and concomitant renal failure, hepatic failure, acute respiratory diseases, or postoperative shock. In addition to extreme vigilance for early recognition ofCandidasepsis in critically ill surgical patients, the high risk for candidemia probably necessitates fungal surveillance cultures and initiation of preemptive antifungal therapy in high-risk surgical patients.

Effect of daily use of an enzymatic denture cleanser on Candida albicans biofilms formed on polyamide and poly(methyl methacrylate) resins: an in vitro study

STATEMENT OF PROBLEM

Candida biofilms on denture surfaces are substantially reduced after a single immersion in denture cleanser. However, whether this effect is maintained when dentures are immersed in cleanser daily is unclear.

PURPOSE

The purpose of this study was to evaluate the effect of the daily use of enzymatic cleanser on Candida albicans biofilms on denture base materials.

MATERIAL AND METHODS

The surfaces of polyamide and poly(methyl methacrylate) resin specimens (n=54) were standardized and divided into 12 groups (n=9 per group), according to study factors (material type, treatment type, and periods of treatment). Candida albicans biofilms were allowed to form over 72 hours, after which the specimens were treated with enzymatic cleanser once daily for 1, 4, or 7 days. Thereafter, residual biofilm was ultrasonically removed and analyzed for viable cells (colony forming units/mm(2)) and enzymatic activity (phospholipase, aspartyl-protease, and hemolysin). Factors that interfered with the response variables were analyzed by 3-way ANOVA with the Holm-Sidak multiple comparison method (α=.05).

RESULTS

Polyamide resin presented more viable cells of Candida albicans (P<.001) for both the evaluated treatment types and periods. Although enzymatic cleansing significantly (P<.001) reduced viable cells, daily use did not maintain this reduction (P<.001). Phospholipase activity significantly increased with time (P<.001) for both materials and treatments. However, poly(methyl methacrylate) based resin (P<.001) and enzymatic cleansing treatment (P<.001) contributed to lower phospholipase activity. Aspartyl-protease and hemolysin activities were not influenced by study factors (P>.05).

CONCLUSIONS

Although daily use of an enzymatic cleanser reduced the number of viable cells and phospholipase activity, this treatment was not effective against residual biofilm over time.

Oral mycobiome analysis of HIV-infected patients: identification of Pichia as an antagonist of opportunistic fungi

Oral microbiota contribute to health and disease, and their disruption may influence the course of oral diseases. Here, we used pyrosequencing to characterize the oral bacteriome and mycobiome of 12 HIV-infected patients and matched 12 uninfected controls. The number of bacterial and fungal genera in individuals ranged between 8-14 and 1-9, among uninfected and HIV-infected participants, respectively. The core oral bacteriome (COB) comprised 14 genera, of which 13 were common between the two groups. In contrast, the core oral mycobiome (COM) differed between HIV-infected and uninfected individuals, with Candida being the predominant fungus in both groups. Among Candida species, C. albicans was the most common (58% in uninfected and 83% in HIV-infected participants). Furthermore, 15 and 12 bacteria-fungi pairs were correlated significantly within uninfected and HIV-infected groups, respectively. Increase in Candida colonization was associated with a concomitant decrease in the abundance of Pichia, suggesting antagonism. We found that Pichia spent medium (PSM) inhibited growth of Candida, Aspergillus and Fusarium. Moreover, Pichia cells and PSM inhibited Candida biofilms (P = .002 and .02, respectively, compared to untreated controls). The mechanism by which Pichia inhibited Candida involved nutrient limitation, and modulation of growth and virulence factors. Finally, in an experimental murine model of oral candidiasis, we demonstrated that mice treated with PSM exhibited significantly lower infection score (P = .011) and fungal burden (P = .04) compared to untreated mice. Moreover, tongues of PSM-treated mice had few hyphae and intact epithelium, while vehicle- and nystatin-treated mice exhibited extensive fungal invasion of tissue with epithelial disruption. These results showed that PSM was efficacious against oral candidiasis in vitro and in vivo. The inhibitory activity of PSM was associated with secretory protein/s. Our findings provide the first evidence of interaction among members of the oral mycobiota, and identifies a potential novel antifungal.

Guideline vulvovaginal candidosis (2010) of the German Society for Gynecology and Obstetrics, the Working Group for Infections and Infectimmunology in Gynecology and Obstetrics, the German Society of Dermatology, the Board of German Dermatologists and the German Speaking Mycological Society

Candida (C.) species colonize the estrogenized vagina in at least 20% of all women. This statistic rises to 30% in late pregnancy and in immunosuppressed patients. The most often occurring species is Candida albicans. Host factors, especially local defense deficiencies, gene polymorphisms, allergic factors, serum glucose levels, antibiotics, psychosocial stress and estrogens influence the risk for a Candida vulvovaginitis. In less than 10% of all cases, non-albicans species, especially C. glabrata, but in rare cases also Saccharomyces cerevisiae, cause a vulvovaginitis, often with fewer clinical signs and symptoms. Typical symptoms include premenstrual itching, burning, redness and non-odorous discharge. Although pruritus and inflammation of the vaginal introitus are typical symptoms, only less than 50% of women with genital pruritus suffer from a Candida vulvovaginitis. Diagnostic tools are anamnesis, evaluation of clinical signs, the microscopic investigation of the vaginal fluid by phase contrast (400 x), vaginal pH-value and, in clinically and microscopically uncertain or in recurrent cases, yeast culture with species determination. The success rate for treatment of acute vaginal candidosis is approximately 80%. Vaginal preparations containing polyenes, imidazoles and ciclopiroxolamine or oral triazoles, which are not allowed during pregnancy, are all equally effective. C. glabrata is resistant to the usual dosages of all local antimycotics. Therefore, vaginal boric acid suppositories or vaginal flucytosine are recommended, but not allowed or available in all countries. Therefore, high doses of 800 mg fluconazole/day for 2-3 weeks are recommended in Germany. Due to increasing resistence, oral posaconazole 2 × 400 mg/day plus local ciclopiroxolamine or nystatin for 15 days was discussed. C. krusei is resistant to triazoles. Side effects, toxicity, embryotoxicity and allergy are not clinically important. A vaginal clotrimazole treatment in the first trimester of pregnancy has shown to reduce the rate of preterm births in two studies. Resistance of C. albicans does not play a clinically important role in vulvovaginal candidosis. Although it is not necessary to treat vaginal candida colonization in healthy women, it is recommended in the third trimester of pregnancy in Germany, because the rate of oral thrush and diaper dermatitis in mature healthy newborns, induced by the colonization during vaginal delivery, is significantly reduced through prophylaxis. Chronic recurrent vulvovaginal candidosis requires a "chronic recurrent" suppression therapy, until immunological treatment becomes available. Weekly to monthly oral fluconazole regimes suppress relapses well, but cessation of therapy after 6 or 12 months leads to relapses in 50% of cases. Decreasing-dose maintenance regime of 200 mg fluconazole from an initial 3 times a week to once monthly (Donders 2008) leads to more acceptable results. Future studies should include candida autovaccination, antibodies against candida virulence factors and other immunological trials. Probiotics should also be considered in further studies. Over the counter (OTC) treatment must be reduced.

Correlation between phospholipase of Candida albicans and resistance to fluconazole

The objective of this study was to compare phospholipase production between fluconazole-resistant and fluconazole-susceptible strains of Candida albicans in order to explore the relationship between resistance to antifungal drugs and virulence of C. albicans. Fifteen each of fluconazole-resistant (MIC ≥ 64 μg ml(-1)) and fluconazole-susceptible (MIC ≤ 8 μg ml(-1)) strains of C. albicans were incubated on egg yolk agar to detect phospholipase activity. Virulence of C. albicans was assessed by the average survival time of infected mice. Expression of phospholipase B1 mRNA and protein were detected by RT-PCR and Western blot method. Significant differences between the two groups of Candida strains were observed in phospholipase activity and average survival time of infected mice. The expression of phospholipase B1 mRNA and protein (both of secreted and intracellular forms) were higher in resistant strains than in susceptible strains. The results indicate that the phospholipase activity of C. albicans may be related to its resistance to antifungal drugs.

Investigations by cell-mediated immunologic tests and therapeutic trials with thymopentin in vaginal mycoses

Objective: According to unsatisfactory therapeutic results in patients with chronically recurrent vaginal candidosis, we investigated if immunologic patient factors could be found and treated.

Methods: In 42 women with chronically recurrent and 20 women with acute Candida albicans vulvovaginitis, as well as 14 women with C. glabrata vaginitis, the following investigations were carried out: identification of yeast species; quantification of T lymphocytes and their subpopulations in sera; proliferation tests of T lymphocytes in vitro; treatment of 18 patients with chronically recurrent vaginal candidosis with the synthetic T-lymphocyte- stimulator thymopentin; and, finally, control of the above-mentioned parameters in the clinical course.

Results: Women with C. albicans vulvovaginitis showed fewer T lymphocytes and subpopulations in the peripheral blood than healthy women. Only the number of non-specific killer (NK) cells, however, was significantly lower in cases of acute C. albicans vulvovaginitis. In women with C. glabrata vaginitis, the number of T lymphocytes in the blood was within the normal range. In vitro proliferation tests using mitogens, bacterial antigens, and commercially available candida antigens with and without addition of thymopentin were carried out on the T lymphocytes of women with chronically recurrent C. albicans vulvovaginitis. These tests revealed no significant differences compared with the other patients with C. albicans infections. The patients were treated with thymopentin. Those women who revealed an increase of initially low numbers of T-helper cells recovered from vaginal candidosis after thymopentin treatment.

Conclusions: The peripheral T lymphocytes may be diminished in patients with chronically recurrent C. albicans vaginitis, and immunologic treatment can reduce the relapse rate.

The role of candidal histolytic enzymes on denture-induced stomatitis in patients living in retirement homes

MATERIAL AND METHODS

Fifty nine elders wearing complete dentures and living in retirement homes in Curitiba (southern Brazil), were divided into two groups: group #1, 26 patients with denture-induced stomatitis and group #2, 33 patients without denture-induced stomatitis. The two groups were evaluated in relation to the degree of denture-induced stomatitis, salivary fungal loads, and secretion of some histolytic enzymes.

RESULTS

Patients from group #1 showed higher degrees of colonisation by Candida albicans (p = 0.031). Candida krusei, Candida tropicalis, and Candida parapsilosis were also isolated, but there were no differences between the groups (p > 0.05). Secretory aspartyl protease (Sap) and chondroitinase did not show significant differences among the isolated Candida spp. in the two groups. Phospholipase secretion rates were higher among the strains of C. albicans from group #2 (p = 0.036). The same behaviour was not detected for non-albicans Candida species.

CONCLUSIONS

The results could infer that differences in the secretion rates of candidal histolytic enzymes should not be imputed as imperative for the progress of denture-induced stomatitis.

Comparison of pathogenicity of various Candida albicans and C. stellatoidea strains

In order to clarify the pathogenicity and the pathogenic factors of various Candida species strains, three strains, NIH A-207 and J-1012 (serotype A), and NIH B-792 (serotype B) of Candida albicans and two strains, ATCC 20408 (karyotype II) and ATCC 36232 (karyotype I) of C. stellatoidea, a synonym for C. albicans, were tested for their lethality to mice, adherence to Hela cells, hydrophobicity, and cell growth under acidic conditions, pH 2.0-5.9. The pathogenicity for mice of all the strains was observed in the order NIH B-792, ATCC 36232, J-1012, NIH A-207, and ATCC 20408. The pathogenicity for mice by all the strains used was well correlated with adherence to the Hela cells, the hydrophobicity, and the cell growth under the acidic condition, pH 2.0. These results emphasize that these specific properties of the C. albicans and C. stellatoidea strains play an important role in the pathogenesis of candidosis.

Genetic relatedness of commensal strains of Candida albicans carried in the oral cavity of patients' dental prosthesis users in Brazil

The aim of this study is to describe the degree of yeast-colonization in diabetic and hemodialysed-users of dental prostheses. Individuals (306) were examined using an oral rinse technique in order to evaluate the incidence of yeast-carriage, and genotype of C. albicans. Yeasts were isolated from 68.4% (91/133) individual's dental prostheses users. Dental prostheses were found to be a significant factor for the yeast colonization (P < 0.05). Overall, the intensity of carriage was higher in diabetic patients as compared with health and hemodialysed individuals (P < 0.05). The isolation rates were: C. albicans (51.7%), C. parapsilosis (20.9%), C. tropicalis (14.3%), C. glabrata (6.6%), C. krusei (3.3%), C. rugosa (1.1%), and Pichia (Pichia ohmeri, 2.2%). Ready-To-Go RAPD Analysis Beads were used and primer OPJ 6 distinguished the C. albicans isolates found in prostheses users. All the isolates were grouped into 11 RAPD profiles in four main clusters and, the average S (AB) for the entire collection of 47 C. albicans isolates were 0.779 +/- 0.178. Over 85% of isolates had a similarity level higher than or equal to 0.8 reinforcing the idea that the use of dental prostheses, independently of the host's clinical condition, probably provides the necessary conditions for these strains to gain a growth-specific advantage over others.

Distribution and phospholipase activity of Candida species in different denture stomatitis types

The aim of this study was to evaluate the correlation between frequency and phospholipase activity of Candida species and denture stomatitis according to Newton's classification. Seventy-five complete denture wearers were evaluated for the presence of yeasts on the palatal mucosa by culture method. In addition, the number of yeast isolates producing phospholipase and amount of this enzyme were determined using egg yolk agar plate method. According to Newton's classification, 25 denture wearers were with healthy palatal mucosa while 50 were with any types of denture stomatitis. The frequency of yeasts was linked to whether subjects had Type II or Type III, but not Type I denture stomatitis. Candida albicans was the most frequently isolated species in denture wearers with and without clinical signs of denture stomatitis and it was the only species produced phospholipase. Although the amount of phospholipase produced by the C. albicans isolates from denture wearers in control and Type II and III DS groups was not significantly different, there was statistically significant difference in the number of C. albicans isolates producing phospholipase between patients with and without clinical signs of DS.

Phenotypic aspects of oral strains of Candida albicans in children with down's syndrome

The aim of this article is to characterize the biological aspects of oral strains of C. albicans in children with Down's syndrome. These yeasts were analyzed as to their macromorphological and enzymatic aspects and were tested as to their in vitro susceptibility to antifungal drugs using broth microdilution to determine the minimum inhibitory concentration (MIC). The morphotyping revealed that all oral C. albicans isolates from children with Down's syndrome promoted the formation of fringes regardless of size, while the control group presented smaller fringes. All oral C. albicans strains produced proteinase, but those with phospholipolytic activity showed greater enzyme capacity in the test group. In vitro susceptibility showed that all oral C. albicans isolates were sensitive to the drugs used.

Malassezia pachydermatis: enzymes production in isolates from external ear canal of dogs with and without otitis

The relationship between production of enzymes and pathogenicity of Malassezia pachydermatis strains was studied. Thirty strains of M. pachydermatis isolated from dogs were used: 15 originating from animals with external otitis and 15 obtained from ears of asymptomatic dogs. The samples, obtained by introduction of a sterile swab into the auditory canal after cleaning the auricle with alcohol-ether solution, were seeded onto Sabouraud dextrose agar with chloramphenicol (100mg/l) and were incubated at 37°C for up to two weeks. The colonies were identified according to their macro-and-micromorphology. All strains were investigated for the production of chondroitin-sulphatase, hyaluronidase, phospholipase and proteinase. Most of the strains showed a high production of the four enzymes. Statistical analysis did not show any differences in the enzymatic activity among the strains. M. pachydermatis originating in normal microbiota as well as in otic secretion from dogs with otitis could produce the four researched enzymes. Probably M. pachydermatis has other virulence factors that are involved in the parasitism.

Similarity of acid proteinases secreted by Candida albicans NIH A-207 and NIH B-792 strains cultured in BSA-supplemented medium

Candida albicans NIH A-207 (serotype A) and NIH B-792 (serotype B) strains secreted one acid proteinases (AP) each in a yeast carbon-based medium supplemented with bovine serum albumin (BSA) as the sole nitrogen source. Isolation of AP from the culture filtrates was achieved by dialysis, followed by DEAE-Sepharose and Biogel P-100 column chromatographies. It was found that both enzymes from the two strains had very similar properties when examined. The molecular weights and isoelectric points were found to be 43 kDa and pH 4.0, respectively. The amino acid components and first 12 N-terminal amino acid sequences were virtually identical in both enzymes. The optimum pH of the enzymes was 3.5-4.0. The enzymes were heat-labile, and decreases in their activities were found above 37 degrees C. The AP activities were completely inhibited by the addition of pepstatin. No other inhibitor among those tested had any effect. The enzymes degraded all proteins examined, especially host defense factors such as immunoglobulin G and the granulocyte colony stimulating factor. The enzymes also caused similar degrees of enhancement of vascular permeability when they were injected into the dorsal skin of guinea pigs.

Activity of hydrolytic enzymes in fungi isolated from diabetic pregnant women: is there any relationship between fungal alkaline and acid phosphatase activity and glycemic control?

Ability to respond to environmental changes and secretion of hydrolases are considered to be important for Candida virulence. In this study we determined and compared the activities of 19 different hydrolases of the fungal strains isolated from diabetic and non-diabetic pregnant women. We also looked for the presence of a relationship between hydrolase activities and glycemic control, and, furthermore, evaluated the influence of gestational age on the activity of hydrolases. Mycological examinations were performed for 119 diabetic pregnant women: 47 with diabetes mellitus type I (DM), 72 with gestational diabetes (GDM), and for 132 healthy women (CON). Samples were collected from the vagina, rectum and oral cavity and cultured on Sabouraud media. The fungal hydrolase activities were evaluated using the API ZYM test (bioMerieux). For the 19 different fungal hydrolases tested, 13 activities were present in the isolated fungal strains. The activity of alkaline phosphatase (ALP) in vaginal strains (p=0.028) and acid phosphatase (ACP) in strains from the vagina (p=0.006) and rectum (p=0.049) was significantly lower in DM than in GDM and CON women. In conclusion, we describe for the first time that fungi isolated from pregnant diabetic women have lower activity of both phosphatases compared to fungi isolated from healthy women. Furthermore, similar differences of mean ALP and ACP activities were observed in the course of pregnancy in strains from the vagina and rectum of DM and CON women. However, strains from DM had lower activity at each stage of pregnancy. The highest activity of ALP and ACP was detected at the beginning, then declined, and had the lowest values between the 24(th) and 33(rd) week of gestation. After that period the activity of both phosphatases increased.

Prevalence of fungi in the vagina, rectum and oral cavity in pregnant diabetic women: relation to gestational age and symptoms

OBJECTIVES

To estimate the prevalence of fungi in the vagina, rectum and oral cavity in pregnant women with diabetes mellitus (DM) type I or gestational diabetes mellitus (GDM) and in healthy controls; to assess the influence of gestational age on the prevalence of fungi; to compare the vaginal symptoms within the groups; and to analyze the multifocality of fungal invasions.

METHODS

A total of 251 women were examined: 47 with DM, 72 with GDM and 132 controls. Samples were collected from the vagina, rectum and oral cavity of all women and cultured on Sabouraud media.

RESULTS

Fungi were found in 59.8% in at least one of the three locations in all women. Vaginal mycosis was diagnosed more often (p < 0.001) in pregnancies with DM [40.4%, odds ratio (OR) 4.3, confidence interval (CI) 2.41-4.85] than with GDM (22.2%, OR 1.84, CI 0.99-2.12) and nondiabetics (13.6%, OR 1.0). The risk of trifocal mycosis was higher in DM women (OR 2.7, CI 1.72-4.45), than in the controls. Only in 27.6% of symptomatic women were fungi detected in vagina. However, 60.4% of women with vaginal mycosis had symptoms. Among women without mycosis, 42.4% were symptomatic, and discharge was more common in the DM group (50%) than in the GDM group (21.4%) and the controls (28.1%; p < 0.002). The prevalence of fungi in the groups was not influenced by gestational age.

CONCLUSIONS

The risk of vaginal mycoses in DM women is more that four times higher and in pregnancies with GDM nearly two times higher than in controls. The risk of trifocal mycosis in DM women is nearly three times higher than in nondiabetics. There is a poor correlation between symptoms of vaginitis and fungal infection. We did not confirm the influence of the gestational age on the prevalence of fungi.

In vitro antifungal susceptibility of Candida spp. isolates from patients with chronic periodontitis and from control patients

Superinfection by Candida can be refractory to conventional periodontal treatments in specific situations, such as in immunocompromised patients. In these cases, the systemic therapy with antifungal drugs could be indicated. The aim of this study was to analyse antifungal susceptibility of Candida spp. strains isolated from chronic periodontitis patients and from control individuals. A total of 39 C. albicans isolates, 9 C. tropicalis, 2 C. glabrata and 5 Candida spp. from control individuals and 30 C. albicans, 3 C. tropicalis and 2 C. glabrata from periodontitis patients were tested. In the control group, 1 isolate of C. glabrata was resistant to ketoconazole and 1 Candida spp. was resistant to amphotericin B, ketoconazole and miconazole. Among the isolates of periodontitis group, 1 (3.33%) C. albicans isolate was resistant to flucytosine and ketoconazole. According to the obtained results, it could be concluded that fluconazole was the most effective drug against the several Candida species studied. There were not expressive differences in the susceptibility of isolates from periodontitis patients or from control individuals.

Pathogenesis, microbiological and clinical aspects of oral candidiasis (candidosis)

The clinical significance of the oral candidiasis (either as independent disorder, or as a part of another disease) is increasing with time. The diagnosis and local treatment of the oral candidiasis may not be satisfactory, this disorder cannot be eliminated without the correct diagnosis and management of the underlying disease. At the same time, some disorders, such as Candida induced leukoplakia, may significantly enhance tumor development. Fungal infection of the mouth is often the initial sign of several immunodeficiency diseases. It is, therefore, very important to clarify the background of a fungal infection, since this may be critical regarding the prognosis.

Inhibitory effect of terbinafine on reactive oxygen species (ROS) generation by Candida albicans

Candida albicans, the most important opportunistic fungal pathogen, is able to generate remarkable amounts of reactive oxygen species (ROS). Since ROS are highly cytotoxic, this mechanism may contribute to the pathogenicity of this yeast, including its invasiveness and the inflammatory response of the host. Terbinafine, a synthetic antifungal agent of the allylamine class, inhibits ergosterol biosynthesis at the level of squalene epoxidase. Furthermore, there is evidence that terbinafine at therapeutic concentrations can be considered a free radical scavenger in vitro and could exert an anti-inflammatory activity in vivo. In this study we investigated whether terbinafine affects the generation of ROS by C. albicans. Blastoconidia of the C. albicans strain 3153A were cultured in YEPG-medium and, subsequently, incubated with different doses of terbinafine (1, 10 and 100 microg ml(-1)) for 10 and 60 min, respectively. ROS generation was measured by lucigenin-enhanced chemiluminescence. Formation of ROS was considerably dependent on cell number. Chemiluminescence signals were measured at a concentration > or = 1 x 10(6) cells ml(-1), with a maximum of 1 x 10(8) cells ml(-)1. Already after 10 min of incubation with terbinafine, a dose-dependent significant inhibition of ROS generation was found (P < 0.05), whereas after 60 min this effect was amplified. In conclusion, terbinafine reduced the ability of C. albicans to generate ROS. Besides the known effect on ergosterol biosynthesis, this mechanism may contribute to its antifungal action.

Phospholipase and protease activities in clinical Candida isolates with reference to the sources of strains

The present study was aimed at determining in vitro phospholipase and protease activities in 95 clinical isolates of various Candida species (C. albicans, C. glabrata, C. guilliermondii,C.kefyr, C. krusei, C. lipolytica, C. lusitaniae, C. parapsilosis, C.rugosa and C. tropicalis). 59 (62.1%) of isolates examined were phospholipase positive and 75 (78.9.9%) were protease positive. 56 (93.3%) of C.albicans isolates tested were phospholipase producers - however only a few strains of C. glabrata and C. kefyr behaved in the same way. Protease activity was detected in 57 (95%) of C. albicans strains tested and in a few strains of C. kefyr, C.lipolytica, C. parapsilosis and C. tropicalis- the remaining isolates were negative. 56 strains of C.albicans and 2 strains of C. kefyr tested produced both phospholipase and protease.

Therapeutic dilemma of fluconazole prophylaxis in intensive care

OBJECTIVE

To review the data concerning the use of prophylactic fluconazole in intensive care patients who are not immunocompromised.

DATA SOURCE

Literature identified through MEDLINE (1966-March 2001) and recent abstracts of data presented at scientific meetings.

DATA SYNTHESIS

The use of fluconazole as a prophylactic antifungal agent is well documented in patients who are immunocompromised or undergoing bone marrow or solid organ transplantation, with supportive results. Recently published data suggest that the use of fluconazole in high-risk surgical patients can be safe and effective for preventing certain candida infections. However, there is growing evidence that the use of fluconazole may be contributing to the higher prevalence of fluconazole-resistant fungal infections.

CONCLUSIONS

The use of prophylactic fluconazole in nonneutropenic patients is controversial. Retrospective and surveillance studies of nosocomial fungal infections suggest that the use of fluconazole may be contributing to the shift in fungal flora causing these infections and that the isolates are more fluconazole resistant. Fluconazole prophylaxis in surgical patients may be justified in patients who are at the greatest risk of developing fungal infections, those requiring multiple intraabdominal surgeries, or those with recurrent gastrointestinal perforations or anastomotic leakages, but there is a lack of randomized controlled trials to recommend its widespread use at this time.

Phospholipases of Candida albicans

Infections due to Candida albicans are frequent and of clinical importance. Especially at a time of increasing organ transplantations, HIV infections, and resistance to antimicrobial agents a profound knowledge of the interaction between C. albicans and host tissue is mandatory. In addition to secreted aspartyl proteinase, dimorphism, cell surface composition, and toxin production phospholipases are a main factor in pathogenicity. Up to the present, many different groups and subgroups of phospholipases have been detected. These different enzymes are related to various types of aggressive and defensive actions. These range from active invasion of host cell tissue to growth control and remodelling of the yeast cell membrane. It is clear that a multiplicity of factors must co-operate to overcome the host's defences. Yet it can be supposed today that phospholipases are one important factor in this complex interaction. Therefore the known phospholipases of C. albicans are described in detail under clinical aspects.

[Enzyme typing of species of the genus Candida isolated from the oral cavity]

The production of phospholipase and proteinase exoenzymes was evaluated in seventy nine samples of Candida isolated from the oral cavity of patients with oral lesions characteristic of candidosis and from individuals presenting a clinically normal mouth, attended at the University of Dentistry of Ribeirão Preto USP. Among the strains of C. albicans isolated from oral lesions, the phospholipase and proteinase were detected in 83.3% and 66.7%, respectively. C. tropicalis and C. parapsilosis produced only proteinase. Regarding the isolated strains from niches without lesions, out of a total of 32 C. albicans, 71.9% presented phospholipase and 68.7% proteinase. C. tropicalis only presented the enzyme proteinase, C. glabrata, C. krusei, C. guilliermondii and Candida spp did not present any of the exoenzymes. Among the samples of C. albicans from both groups, the enzymotype 22 (positive phospholipase and proteinase weakly positive), was prevalent. Different enzymotypes of the same species were detected in samples collected from the same patient.

Identification of sialic acids on the cell surface of Candida albicans

The cell-surface expression of sialic acids in two isolates of Candida albicans was analyzed by thin-layer and gas chromatography, binding of lectins, colorimetry, sialidase treatment and flow cytofluorimetry with fluorescein-labeled lectins. N-acetylneuraminic acid (NANA) was the only derivative found in both strains of C. albicans grown in a chemically defined medium. Its identification was confirmed by mass spectrometry in comparison with an authentic standard. The density of sialic acid residues per cell ranged from 1. 6x10(6) to 2.8x10(6). The surface distribution of sialic acids over the entire C. albicans was inferred from labeling with fluorescein-Limulus polyphemus and Limax flavus agglutinins and directly observed by optical microscopy with (FITC)-Sambucus nigra agglutinin (SNA), abrogated by previous treatment of yeasts with bacterial sialidase. Sialidase-treated yeasts generated beta-galactopyranosyl terminal residues that reacted with peanut agglutinin. In C. albicans N-acetyl-neuraminic acids are alpha2,6- and alpha2,3-linked as indicated by yeast binding to SNA and Maackia amurensis agglutinin. The alpha2,6-linkage clearly predominated in both strains. We also investigated the contribution of sialic acids to the electronegativity of C. albicans, an important factor determining fungal interactions in vivo. Adhesion of yeast cells to a cationic solid phase substrate (poly-L-lysine) was mediated in part by sialic acids, since the number of adherent cells was significantly reduced after treatment with bacterial sialidase. The present evidence adds C. albicans to the list of pathogenic fungi that synthesize sialic acids, which contribute to the negative charge of fungal cells and have a role in their specific interaction with the host tissue.

Non-albicans Candida species isolated from plastic devices

In this work we point out an occurrence of non-albicans Candida species isolated from catheters, cannulas and drains. We detected eight non-albicans Candida species in 49 examined samples: C. parapsilosis (n = 26), C. tropicalis (n = 12), C. krusei (n = 4), C. claussenii, C. mesenterica (n = 2 for each), C. guilliermondii, C. kefyr and C. lusitaniae (n = 1 for each). Material examined from children hospitalized in intensive care units was the most frequent. Eight samples were from the oncology department, seven from the surgery department, six from the anaesthesiology department, four from the dialysis unit, two from the hematology department, one from the internal medicine department and one from the stomatology department. We examined cannula scraping 26 times (53%), catheter scraping 14 times (28.6%) and drain scraping nine times (18.4%).

Phospholipid molecular species distribution of some medically important Candida species analysed by fast atom bombardment mass spectroscopy

The aim of this study was to obtain detailed information on phospholipids (PL) of the medically important Candida species and to determine their possible chemotaxonomic significance. Lipids were extracted from 22 strains representing 8 Candida species and their PL molecular species distributions were determined by Fast Atom Bombardment Mass Spectroscopy (FAB MS) in negative ion mode. Fifteen major lower mass peaks (m/z 221 to 289) were attributable to the expected presence of carboxylate anions and 24 major higher mass peaks (m/z 557 to 837) were attributable to phospholipid anions. Major carboxylate peaks were of the following m/z and identities : 253, C16:1; 255, C16:0; 277, C18:3; 279, C18:2; 281, C18:1; and 283, C18:0. The most abundant peaks consistent with the presence of phospholipid molecular species anions include those of m/z 673, 743, 833, 834 and 836 tentatively identified as phosphatidic acid (PA) (34:1), phosphatidylglycerol (PG) (34:3), phosphtidylinositol (PI) (34:2) and two unknown molecular species. This profile is diagnostic for the genus Candida. Quantitative differences were observed between different Candida species. Thus, polar lipid molecular species distribution in Candida spp. has chemotaxonomic significance, especially so in the case of carboxylate anions.

The plasma membrane H(+)-ATPase of fungi. A candidate drug target?

The fungal plasma membrane H(+)-ATPase possesses important attributes that make it desirable as a target for antifungal drug discovery. First, the enzyme is essential to fungal cell physiology, being required for the formation of a large electrochemical proton gradient and the maintenance of intracellular pH. While complete inhibition of the proton pump will certainly be lethal, partial inhibition can also be lethal depending on the environment of the cell (gastrointestinal tract, etc.). Thus, an effective antagonist of the proton pump will be fungicidal, which is an important attribute for a drug being developed to treat opportunistic infections in the severely immunocompromised. Secondly, the well-characterized biochemistry and genetics of the H(+)-ATPase (encoded by the PMA1 gene) facilitate detailed analysis of interaction of lead or model compounds with the enzyme. Studies with omeprazole, which is not suitable as an antifungal but can be used under selective conditions to target H(+)-ATPase, indicate that the enzyme can be inhibited from its extramembrane surface. Detailed genetic analysis suggests that modification of amino acids in transmembrane segments 1 and 2 can either enhance or diminish the omeprazole sensitivity of the H(+)-ATPase, depending on the nature and location of the amino acid substitution. This region in mammalian P-type enzymes has been implicated in the interaction of cardiac glycosides and reversible gastric pump inhibitors. Our results suggest that this region in the H(+)-ATPase may be valuable as a potential interaction domain for antifungal agents. Finally, a number of primary and secondary screens are available to identify compounds that are targeted to the H(+)-ATPase and affect one or more functional properties. These screens assess enzyme functionality in the cell as well as in vitro and can be used in 96-well microplate format to facilitate high through-put screening. These screens have already yielded promising H(+)-ATPase-directed antagonists. In conclusion, the plasma membrane H(+)-ATPase is a highly desirable target for the development of novel antifungal therapeutics.

Molecular cloning of a gene encoding translation initiation factor (TIF) from Candida albicans

The differential display technique was applied to compare mRNAs from two clinical isolates of Candida albicans with different virulence; high (potent strain, 16240) and low (weak strain, 18084) extracellular phospholipase activities. Complementary DNA fragments corresponding to several apparently differentially expressed mRNAs were recovered and sequenced. A complementary DNA fragment seen distinctly in the potent phospholipase producing strain was highly homologous to the yeast translation initiation factor (TIF). The selected DNA fragment was then used as a probe to isolate its corresponding complementary DNA clone from a library of C. albicans genomic DNA. The sequence of isolated gene revealed an open reading frame of 1194 nucleotides with the potential to encode a protein of 397 amino acids with a predicted molecular weight of 43 kDa. Over its entire length, the amino acid sequence showed strong homology (78-89%) to Saccharomyces cerevisiae TIF and (63-80%) to mouse eIF-4A proteins. Therefore, our C. albicans gene was identified to be TIF (Ca TIF). Northern blot analysis in the two strains of C. albicans revealed that Ca TIF expression is 1.5-fold higher in the potent phospholipase producing strain. The restriction endonuclease digestion of genomic DNA from this potent strain revealed at least two hybridized bands in Southern blot analysis, suggesting two or more closely related sequences in the C. albicans genome.