In vitro antifungal resistance in Candida albicans from HIV-infected patients with and without oral candidosis.

The main purpose of this study has been to determine the in vitro antifungal susceptibility of clinical isolates from HIV-infected or AIDS patients, depending on the presence of oral candidosis. The oral cavity of 307 HIV-infected or AIDS patients was examined and an oral swab was cultured on Sabouraud glucose agar and studied by conventional mycological methods. In vitro antifungal susceptibility to amphotericin B, nystatin, fluconazole, itraconazole and ketoconazole was tested by disk diffusion with Neo-Sensitabs tablets (Rosco Diagnostica, Dinamarca). One hundred and thirty five Candida albicans isolates (91 serotype A, 38 serotype B, three C. albicans variety stellatoidea and three untyped isolates), three Candida krusei and two Candida glabrata were obtained. All the isolates were susceptible to nystatin and amphotericin B. However, 7.9% isolates were resistant to fluconazole and 2.9% isolates were resistant to ketoconazole or itraconazole. Nearly all C. krusei and C. glabrata isolates, 31% patients with candidosis and 20% Candida-colonized patients showed decreased susceptibility to azoles. This study shows that polyenes had a great in vitro efficacy against clinical isolates from HIV-infected patients and that in vitro resistance to azoles is not as high as observed in other countries.     

Prevalence of oral lesions by Candida sp.: Their varieties and serotypes in a population of patients with AIDS under a highly active antiretroviral therapy.

The aim of this study has been to determine the prevalence of oral candidiasis and oral Candida carriers in an AIDS population under highly active antiretroviral therapy. Eighty-six AIDS patients treated with an antiretroviral combination (indinavir o ritonavir o saquinavir + zidovudine [AZT] + lamivudine [3TC]). Patients were grouped attending the predisposing factors for HIV infection in: intravenous drug users (IDU), heterosexuals, homosexuals, patients using hematological products or having unknown factors. Oral cavity was examined and an oral specimen was inoculated in a chromogenic culture medium (Albicans ID, bioMérieux, France). The prevalence of oral Candida lesions was 30.2% and Candida was isolated from 54.7% of patients. The predominant species was C. albicans serotype A in all the groups with the exception of homosexual patients, were C. albicans serotype B was the predominant. The IDU group showed the higher prevalence of Candida lesions and oral yeasts colonization, followed by the group of heterosexuals and homosexuals. An association was found between the presence of lesions and/or Candida spp. and the clinical stage or the viral concentration. The species Candida dubliniensis was isolated in the oral samples of two patients with candidosis and in two individuals without oral candidosis. The finding of this species in Spanish patients can be added to the data obtained in epidemiological studies in other countries.     

Salivary pH and culture determinations in HIV infected and non-HIV infected patients with oral candidosis

The aim of the present study was to determine the salivary pH in HIV (Human Immunodeficiency Virus) positive(+) and negative(-) patients and in a control group, for assessing if variations or changes in pH are related to the development of oral candidosis and the species isolated. The sample comprised 120 patients from the Infectology Unit of the Mexico General Hospital, and from the School of Dentistry, UNAM. Three study groups were performed: with oral candidosis HIV+, with oral candidosis HIV-, and a control group. All patients filled out a clinical data questionnaire and signed an informed consent document. A 2 ml sample of non-stimulated saliva was obtained from each patient. The pH was measured and the sample was cultured on dextrose Sabouraud agar. The Candida species determinations were performed by the API 20 C AUX system and statistically analyzed. In the HIV+ group, the pH mean was 6.17, with most prevalence of Candida albicans type I and pseudomembranous candidosis. In the HIV- group prosthesis users, the pH mean was 6.29, with most prevalence of C. albicans type I, but with erythematous candidosis. The control group showed a mean pH of 6.78. A statistically significant difference among pH values was found (F= 15.45 p<0.01). The present study revealed that in HIV+ patients, the most significant predisposing factors are: immunosuppression, antibiotic therapy, bad hygiene, anemia, leucoplakia, and diabetes. The salivary pH with acidic values (more in HIV+ patients) significantly favors candidosis development, specially for C. albicans and C. glabrata species and primarily the pseudomembranous and erythematous clinic types. The pH is not a determinant for Candida growth, but could affect the adherence and invasiveness of the yeast.     

Prevalence and Exoenzyme Secretion by Candida Albicans Isolates from Oral and Vaginal Mucosas of HIV-Infected Women

A cross-sectional study was performed to evaluate the prevalence and the aetiology of forms of mucosal fungal infections of HIV-negative and HIV-positive women. Candida albicans was the predominate specie isolated from both groups of patients, with remarkable proportion of isolation from symptomatic women. All 239 C. albicans isolates, regardless of their source, showed activity of proteinase and phospholipase. It was verified that isolates with particularly higher levels of exoenzymes production were significantly more common in HIV-positive patients. However, isolates obtained from the HIV-positive patients in use of HAART, with protease inhibitor, presented lower levels of these exoenzymes, similar to the levels observed in the isolates from HIV-negative patients.     

Candida glabrata, Candida parapsilosis and Candida tropicalis: biology, epidemiology, pathogenicity and antifungal resistance

The incidence of infections caused by Candida species (candidosis) has increased considerably over the past three decades, mainly due to the rise of the AIDS epidemic, an increasingly aged population, higher numbers of immunocompromised patients and the more widespread use of indwelling medical devices. Candida albicans is the main cause of candidosis; however, non-C. albicans Candida (NCAC) species such as Candida glabrata, Candida tropicalis and Candida parapsilosis are now frequently identified as human pathogens. The apparent increased emergence of these species as human pathogens can be attributed to improved identification methods and also associated with the degree of diseases of the patients, the interventions that they were subjected and the drugs used. Candida pathogenicity is facilitated by a number of virulence factors, most importantly adherence to host surfaces including medical devices, biofilm formation and secretion of hydrolytic enzymes (e.g. proteases, phospholipases and haemolysins). Furthermore, despite extensive research to identify pathogenic factors in fungi, particularly in C. albicans, relatively little is known about NCAC species. This review provides information on the current state of knowledge on the biology, identification, epidemiology, pathogenicity and antifungal resistance of C. glabrata, C. parapsilosis and C. tropicalis.     

Serotyping of Candida albicans isolated from clinical specimens

A specific antiserum to Candida albicans serotype A was prepared absorbing a total antiserum with Candida albicans serotype B cells. This specific antiserum was used for serotyping C. albicans strains obtained from patients in different hospitals of Havana City, Cuba. Two hundred strains (95.2%) were serotype A, the remaining 10 (4.8%) were serotype B. Results were also correlated with strains isolated from the specimen origin, sex and race of the patient. The usefulness of this specific antiserum to determine C. albicans serotypes and its therapeutic value are pointed out.     

118株口腔致病念珠菌病原学特征及药敏结果分析

目的调查分析临床致病口腔念珠菌菌种分布及对氟康唑、伊曲康唑、制霉菌素、5-氟胞嘧啶和酮康唑的药物敏感性,以提供临床用药依据。方法收集口腔真菌感染患者标本,常规涂片镜检、培养,对酵母样生长菌落用生物梅里埃公司API20AUX进行菌种鉴定。对其中的念珠菌进行药敏分析。结果共收集141例临床口腔真菌病标本,其中118株念珠菌中,白念珠菌87株（73.7%）,热带念珠菌15株（12.7%）,高里念珠菌6株（5.1%）,光滑念珠菌4株,其他念珠菌6株。口腔念珠菌对氟康唑、伊曲康唑、制霉菌素、5-氟胞嘧啶和酮康唑的耐药率分别为5.1%、1.7%、0%、3.4%、5.1%。结论解放军324医院口腔真菌感染主要为长期应用抗生素的老年患者。口腔念珠菌病仍以白念珠菌为主,对常用抗真菌药物呈不同程度的耐药,应进行真菌常规菌种鉴定及药敏试验。     

Candida proteinases and candidosis

Infections caused by the opportunistic yeast pathogen, Candida albicans, are becoming increasingly important. Superficial Candida infections, particularly those of the mouth and vagina, are very common; for example, candidal vaginitis plaques millions of women worldwide, often proving refractory to treatment. Systemic candidosis is much rarer, but it is an important hazard of modern medical procedures such as transplant surgery, i.v. hyperalimentation, and immunosuppressive therapy. One significant virulence factor of C. albicans is its ability to secrete extracellular acid proteinase. This attribute is shared by C. tropicalis and C. parapsilosis, but not by other less pathogenic Candida species. The enzymes produced by these yeasts are all carboxyl proteinases capable of degrading secretory IgA, the major immunoglobulin of mucous membranes. Some have keratino- or collagenolytic activity. Two secretory proteinases of C. albicans have been purified and characterized; their properties are reviewed. Possible applications of this work to the treatment and diagnosis of candidosis are discussed.     

Outbreak of systemic Candida albicans in intensive care unit caused by cross infection.

The first documented outbreak of systemic candidosis shown to be due to cross infection with a particular strain of Candida albicans is reported. Over nine months in an intensive care unit 13 patients developed definite and one probable systemic candidosis. Twenty five further patients had superficial candidal infections. The strain that caused the outbreak (serotype A, morphotype A1, biotype 0/(1)5 5/7) was responsible for all the cases of systemic candidosis acquired in the intensive care unit, 11 (44%) of the superficial candidal infections in the unit, and 17% of candidal infections outside the unit but in the same hospital. The strain was also isolated from oral swabs taken from four nurses working in the unit and the hands of one of these nurses. Two out of 17 nurses were shown to have acquired the strain on their hands when examined immediately after nursing systemically infected patients. No environmental source could be identified. The strain also showed enhanced survival in handwashing experiments and was relatively resistant to Hibiscrub. Management of patients with systemic candidosis might include measures to prevent cross infection and handwashing with disinfectants that are active against candida.     

Study of acute vulvovaginitis in sexually active adult women, with special reference to candidosis, in patients of the Francisco J. Muñiz Infectious Diseases Hospital

The results of microbiological vaginal secretions samples obtained from 749 women (from July 2001 to July 2002) were studied in the Bacteriology Unit of the Francisco Javier Mu?iz Hospital from Buenos Aires. All patients suffered acute vulvovaginitis were child bearing and sexually active women, 334 of them were HIV-positive. The following are the results of the microbiological studies: Lactobacillus spp 50.6%, Gardnerella vaginalis 25.6%, Candida spp 17.4%, Trichomonas vaginalis 5.3%, Neisseria gonorrhoeae 0.3% and B group Streptococcus 0.8%. Candida vaginitis was significantly more frequent in HIV-positive patients, (21.6% vs 14%; p = 0.0086); meanwhile, trichomoniasis was less common although the difference was not statistically significant (3.6 vs 6.7%, p = 0.0810). The following Candida species were isolated in this study: Candida albicans 76.8%, Candida glabrata 15.6%, Candida parapsilosis 2.9%, Candida tropicalis 1.5% and Candida krusei 0.7%. Eight cases (6.2%) of vaginitis were produced by two Candida species (C. albicans and C. glabrata), and in three cases (2.17%) Saccharomyces cerevisiae were isolated. Five women suffering acute vaginitis with Candida spp presented another etiologic agent of vaginal infection, three cases T. vaginalis and two cases G. vaginalis. The following are some of the most important findings of this study: 1) Half of the patients presented a normal microbial biota; 2) Candida spp vaginitis was significantly more frequent among HIV-positive women; 3) we observed a high incidence of Candida glabrata infections (15.9%), 4) 6.2% of vaginal candidiasis were caused by more than one Candida species and, 5) the susceptibility pattern of C. albicans and C. glabrata isolates against fluconazole was similar to the one observed in other studies. The majority of C. albicans isolates were susceptible to fluconazole (MIC90 = 0.5 microg/ml) meanwhile C. glabrata strains were much less susceptible to this drug (MIC50 and MIC90 = 32 microg/ml).     

Multicenter Brazilian study of oral Candida species isolated from AIDS patients

Oropharyngeal candidiasis continues to be considered the most common opportunistic disease in Aids patients. This study was designed to investigate species distribution, serotype and antifungal susceptibility profile among Candida spp. isolated from the oral cavity of Aids patients recruited from six Brazilian university centers. Oral swabs from 130 Aids patients were plated onto CHROMagar Candida medium and 142 isolates were recovered. Yeast isolates were identified by classical methods and serotyped using the Candida Check or target system-Iatron. Antifungal susceptibility testing was performed according to the NCCLS microbroth assay. C. albicans was the most frequently isolated species (91%), and 70% of the isolates belonged to serotype A. We detected 12 episodes of co-infection (9%), including co-infection with both serotypes of C. albicans. Non-albicans species were isolated from 12 episodes, 50% of them exhibited DDS or resistance to azoles. Otherwise, only 8 out 130 isolates of C. albicans exhibited DDS or resistance to azoles. Brazilian Aids patients are infected mainly by C. albicans serotype A, most of them susceptible to all antifungal drugs.     

Experimental candidosis and recovery of Candida albicans from the oral cavity of ovariectomized rats

The aim of this study was to analyze the development of candidosis and the recovery of C. albicans from the oral cavity of ovariectomized and sham-ovariectomized rats. One hundred and twenty-four rats originally negative for Candida spp. in the oral cavity were divided into two groups: ovariectomized and sham-ovariectomized. Fifty-eight ovariectomized and the same quantity of sham-ovariectomized rats were inoculated with C. albicans for the study of candidosis development and recovery of yeast. Four animals from each group were not inoculated with yeast suspension and were submitted to tongue dorsum morphologic analysis by optical and scanning electron microscopy. The development of candidosis in the tongue dorsum was observed by optical and scanning electron microscopy in the periods of 6 hr, 24 hr, 7 days and 15 days after the last inoculation. Recovery of C. albicans was performed by oral samples plating on Sabouraud agar after 1, 2, 5 and 7 days and progressively at each 15-day interval until negative cultures for yeasts were obtained. The results were analyzed by Mann-Whitney and Student's t tests. The tongue dorsum of sham-ovariectomized and ovariectomized rats, not infected by Candida, presented normal aspect. Among the infected rats, the ovariectomized group showed less occurrence of candidosis lesions and lower recovery of C. albicans from the oral cavity in relation to the sham-ovariectomized group. It could be concluded that candidosis was less frequent from the oral cavities of ovariectomized rats in relation to sham-ovariectomized.     

Effect of dietary carbohydrates on the in vitro epithelial adhesion of Candida albicans, Candida tropicalis, and Candida krusei

Adhesion to epithelial surfaces is considered as a critical step in the pathogenesis of oral candidosis. Therefore, the effects of the most commonly consumed dietary carbohydrates on the adhesion of Candida albicans, Candida tropicalis, and Candida krusei to monolayered HeLa cells were investigated. Adherence of C. albicans and C. tropicalis appeared significantly promoted by incubation in defined medium containing a high concentration (500 mM) of fructose, glucose, maltose, and sucrose (p < 0.001). C. albicans organisms grown in sucrose elicited maximal increase in adhesion, whereas adhesion of C. tropicalis and C. krusei was enhanced to the greatest extent when cultured in glucose. Maltose and fructose also promoted adherence of C. albicans and C. tropicalis (p < 0.001), but to a lesser extent than sucrose and glucose. On the other hand, sorbitol-grown yeasts demonstrated a marginal increase in adhesion (p > 0.01). Xylitol only significantly reduced adherence of C. albicans (p < 0.001). These results suggest that the frequent consumption of carbohydrates, such as sucrose, glucose, maltose, or fructose, might represent a risk factor for oral candidosis. The limitation of their consumption by substituting xylitol or sorbitol could be of value in the control of oral Candida colonization and infection.     

Contribution to the study of dermatomycosis in Catalonia

We report the results of a study which aim was the mycological identification of specimens coming from patients included in a clinical trial. A total of 445 specimens from patients with clinical diagnosis of dermatomicosis were processed during 8 months (138 pityriasis versicolor, 28 cutaneous candidosis and 279 dermatophytosis). A 48% of pityriasis versicolor cultures were positive for Malassezia furfur, 50% of candidosis cultures were positive for yeasts and 67% of dermatophytosis cultures were positive for dermatophytes. According to our results Candida albicans was the principal causative agent for cutaneous candidosis and Trichophyton mentagrophytes and Trichophyton rubrum were the most frequent isolated species causing dermatophytosis.     

Heterogeneity of metallo and serine extracellular proteinases in oral clinical isolates of Candida albicans in HIV-positive and healthy children from Rio de Janeiro, Brazil

Candida yeasts frequently cause life-threatening systemic infections in immunocompromised hosts. In the present study, gelatin-SDS-PAGE analysis was used to characterize extracellular proteinases in 44 oral clinical isolates of Candida albicans from HIV-positive (29/50) and healthy children (15/50). Our survey indicates that these oral clinical isolates of C. albicans have complex extracellular proteolytic activity profiles, which illustrates the heterogeneity of this species. We showed four distinct proteolytic patterns composed of distinct serine (30-58 kDa) and metalloproteinase (64-95 kDa) activities, based on the inhibition profile with phenylmethylsulfonyl fluoride and 1,10-phenanthroline, respectively. This is the first report on secreted serine and metalloproteinases present in the culture supernatant fluids of C. albicans; however, we did not observe a significant correlation between proteolytic profile expressed by the C. albicans isolates from HIV-positive children and CD4(+) T cell count and plasma viral load.     

Prevalence of Candida albican serotypes in blood isolates in Chile, and first report of Candida dubliniensis candidemia

Our main goal was to determine the prevalence of C. albicans serotypes isolates from blood cultures and identify the presence of C. dubliniensis. We studied 47 strains identified as C. albicans by conventional methods, 28 were isolated from children and 19 from adult patients. The strains were re-identified by standard methods and phenotypic screening as xylose assimilation and growth at 42 degrees C. API ID 32C (bioMérieux) was employed with the C. dubliniensis suspected strains and confirmation was made by molecular fingerprinting using random amplified polymorphic DNA (RAPD). The C. albicans serotype was determined by agglutination with antiserum anti-antigen 6 from cell wall (Candida Check, Iatron Inc., Japan) and the in vitro susceptibilities were evaluated by a microdilution method. From 47 strains, 46 were confirmed as C. albicans, 31 of them (67%) were serotype A. Adult patients presented a high prevalence of serotype A (95%) and children presented a frequency of 52% of the serotype B (p<0.05). We confirmed the identification of C. dubliniensis in one strain isolated from an infant. All serotype B strains were susceptible to fluconazole, itraconazole and amphotericin B. On the other hand, 3% and 6% of serotype A strains were "susceptible dose dependent" to fluconazole and itraconazole, respectively. C. albicans serotype A was predominant in adult candidemia and its distribution was homogenous in children patients. All strains were highly susceptible to antifungals. We report here the first case of C. dubliniensis candidemia in South America.     

The effect of azidothymidine on germ tube formation in Candida albicans

Candida albicans have a marked propensity to cause infections in AIDS patients. A virulent trait of C. albicans is the yeast-hypha transition (Y-->H) which is influenced, in vitro and in vivo, by several factors. Since azidothymidine (AZT) is used in HIV-positive patients, the effect, in vitro, of different concentrations of AZT on C. albicans Y-->H transition was evaluated. C. albicans isolated from HIV-negative and HIV-positive patients were used and strains of C. tropicalis isolated from HIV-positive patients were also tested. AZT concentrations from 0.01 microg/ml to 10 microg/ml did not have any influence on the Y-->H transition, whereas 100 microg/ml AZT significantly inhibited the germ tube formation. AZT did not influence the formation of pseudohyphae in C. tropicalis. It is suggested that C. albicans infection observed in HIV-positive patients was not influenced by AZT therapy, because at currently used dosages, the Y-->H transition was not expected to increase.     

Discrimination between<Emphasis Type="Italic">Candida albicans</Emphasis> and<Emphasis Type="Italic">Candida dubliniensis</Emphasis> isolated from HIV-positive patients by using commercial method in comparison with PCR assay

Nineteen clinical isolates of Candida albicans and C. dubliniensis were isolated from patients (majority of them HIV-positive) in Slovakia, Brazil, Thailand and Japan. Species discrimination was performed by using growth on CHROMagar Candida, commercial biochemical set API 20C AUX, germ-tube test in human serum, growth at 42 and 45 degrees C on Sabouraud-dextrose agar as well as on CHROMagar Candida, assimilation of D-xylose and methyl alpha-D-glucoside by glass-tube test, and production of chlamydospores. These tests were completed by PCR using Cd-oligo2/F and Cd-oligo2/R primer pair specific for C. dubliniensis. Six clinical isolates were confirmed to be C. dubliniensis, remaining 13 strains were determined as C. albicans. The use of conventional method showed that the determination is markedly influenced by personal evaluation suggesting the necessity of using the combination of many tests to obtain correct results comparing with accurate and rapid PCR assay. For discrimination between C. albicans and C. dubliniensis we recommend the combination of primo-cultivation on CHROMagar, followed by germ-tube test and PCR.     

Minimal inhibitory concentrations of Candida species to five antifungals by using the reference dilution micromethod and the E-test.

It is accepted that the frequency of candidosis has increased during the last decade, specially in hospitalized patients. The more frequent use of azole antifungals and the recognition of isolates of Candida sp resistant to these and other drugs such as 5-fluorocytosine constitute a great need for a reproducible and useful C. albicans in vitro susceptibility testing method for monitoring antifungal therapy in clinical mycological laboratories. The E-test is a novel agar diffussion technique for testing the susceptibility of yeasts against a defined continous gradient of drug and could be used by most clinical laboratories. In this study the E-test and the NCCLS reference microbroth method (M27-P guidelines) were used to determine the MICs of amphotericin B, 5-flucytosine, itraconazole, fluconazole and ketoconazole for 50 clinical isolates of Candida albicans, Torulopsis glabrata, C. tropicalis and Hansenula anomala and five reference ATCC strains. The main purpose of the study was to compare the results obtained by the two methods. In general good agreement (+/- 1 dilution) was otained between both methods, despite differences observed for some species-antifungal combinations in which the MICs were lower by the E-test than by the microbroth method. MICs for C. albicans and T. glabrata to amphotericin B were < 0.50 microg/mL. Two isolates of C. albicans and two others of H. anomala, showed MIC < 8 microg/mL for 5- flucytosine. All isolates of T. glabrata and 40% of C. albicans showed MICs > 16 microg/mL for fluconazole. The results of this study indicate that E-test is an alternative for susceptibility testing to the NCCLS reference method. Because its simplicity it seems to be an easier test for routine clinical laboratories.     

Proteolytic activity of clinical Candida albicans isolates in relation to genotype and strain source

Proteolytic activity is regarded as one of the most important virulence factors of Candida albicans. Several authors recently demonstrated that some karyotypes and genotypes harbouring a group I self-splicing intron (CaLSU) located in the gene encoding the large rRNA subunit showed a high level of proteinase production. The aim of this study was to investigate the correlation between the level of proteinase production and the presence of the CaLSU intron in C. albicans isolates originating from the blood and respiratory tracts (sputum/pharyngeal swabs) of patients with and without oropharyngeal candidosis. The results revealed statistically significant differences in genotype distribution and the level of proteinase production between the C. albicans isolates obtained from blood and from the respiratory tract. Genotype A, without the intron, was prevalent in all groups of strains and its prevalence was higher among isolates from blood (75%) and from patients with candidosis (80%) compared with strains from colonisation (as opposed to infection) (57.8%). Isolates from blood produced significantly less proteinase than isolates from the respiratory tract (p<0.02), and this difference should be attributed to lower proteinase production of genotypes B and C from blood compared with genotypes B and C from the respiratory tract (p<0.01). The higher proteinase production of genotype B than of genotype A was found among respiratory tract isolates only. The presented data indicate that the association between proteinase production and the CaLSU intron depends on the strains' population. Further study is needed on well-defined groups of clinical isolates to elucidate whether the observed diversity in proteinase production plays a role in the selection of strains inducing bloodstream infections.