[Identification, cloning and characterization of the gene for the secretory aspartate protease of Candida albicans].
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Amino Acid Sequence↗
Biomedical subjects
F C Odds
Publications and source records attributed to F C Odds.
Sequence of the Candida albicans gene encoding the secretory aspartate proteinase.
The gene encoding the Candida albicans aspartate proteinase that is secreted by cells grown in protein-containing media was cloned from a C. albicans genomic bank. The base sequence of the insert shows a 1173 bp open-reading frame and indicates an amino acid sequence typical of aspartate proteinases, with amino acid sequence homology to other enzymes of this class and a putative signal peptide consisting of 50 amino acids upstream of the active enzyme.
Amino Acid Sequence↗
Expression of an epitope by surface glycoproteins of Candida albicans. Variability among species, strains and yeast cells of the genus Candida.
Expression of an antigenic epitope reactive with an IgM monoclonal antibody was studied in 253 Candida isolates by direct agglutination. Isolates of Candida albicans reacted significantly more often with the antibody than did isolates of other species. The agglutination scores for C. albicans isolates from sources associated with possible deep-seated Candida infection were significantly higher than for those from other sources. However, there was considerable overlap of scores between these two groups so that the functional significance of the association is uncertain. There were no associations between agglutination score and C. albicans biotype: multiple isolates from individual patients gave similar agglutination scores. Expression of the epitope within colonies of cloned strains was studied by autoradiography of colony blots on nitrocellulose and by immunoperoxidase staining of colonies in situ. It was found that the epitope was expressed variably by portions of colonies of both agglutination-positive and agglutination-negative strains. Indirect immunofluorescence revealed that expression of the epitope at the surface of C. albicans germ tubes and their associated buds was variable from cell to cell. It was not directly related to morphology or stage of growth of the cells.
Agglutination Tests↗
Numerical taxonomic analysis of imperfect yeast species in Candida and Torulopsis shows no basis for generic separation.
A numerical taxonomic analysis was performed on 79 phenotypic characters of 147 imperfect yeast species currently assigned to the genus Candida. The characters used were drawn from two monographs on yeast taxonomy. The analysis revealed 10 clusters of three or more species that were similar at the level of 75% or more, and seven clusters containing only one or two species. None of the 10 major clusters contained exclusively species that were traditionally assigned to the genus Torulopsis, while the 12 Candida species of basidiomycetous affinity fell into three clusters with only one species of ascomycetous affinity included. Statistical determination of the five most important differential characters for each cluster failed to show the property of pseudomycelium/mycelium formation as significant for any cluster. The study provides no evidence to support a distinction between taxa that were formerly divided between the genera Candida and Torulopsis and supports previous proposals that these genera should be fused.
Candida↗
Academic selection criteria and subsequent performance.
In this paper we have attempted to determine if there are any aspects of the academic history of a student, prior to admission to the University of Leicester medical course, that correlate with his or her subsequent performance in that course. The analyses presented suggest that a student's overall performance in GCE O- and A-level examinations correlates with subsequent performance at various stages of the medical course. In addition, there is a correlation between performance in the medical course and performance in A-level chemistry and biology but not mathematics, physics or general studies. Students who resat two or more A-level subjects performed at a lower level throughout the course than those with only one or no resits. These results emphasize the importance of academic criteria in the medical student selection process.
Achievement↗
Collaborative investigation of variables in susceptibility testing of yeasts.
A multicenter study was performed to evaluate the effect of medium, incubation time (24 and 48 h), and temperature (30 and 35 degrees C) on intra- and interlaboratory variations in MICs of flucytosine, amphotericin B, and ketoconazole for yeasts. Testing was performed on coded isolates of Candida species (11 strains) and Cryptococcus neoformans (2 strains) by using a standard macrodilution protocol 11 laboratories. Four chemically defined media buffered to pH 7.0 with morpholinepropanesulfonic acid were evaluated, including buffered yeast nitrogen base, synthetic amino acid medium-fungal, RPMI 1640 medium, and high-resolution antifungal assay medium. Intralaboratory variability was less than or equal to fourfold for 97% of the replicate sets of data. The highest level of interlaboratory agreement, irrespective of antifungal agent or incubation conditions, was observed with RPMI 1640 medium. Intralaboratory variability was less than or equal to fourfold for 93% of the determinations with ketoconazole and 100% with flucytosine tested in RPMI 1640 medium at 35 degrees C for 24 h. Variability in amphotericin B results was less than or equal to fourfold for 81% of the determinations in RPMI 1640 medium at 35 degrees C for 48 h. The rank order of MICs within each antifungal test group was similar among the various laboratories and was generally in agreement with the reference rank order regardless of the test medium that we used.
Amphotericin B↗
Antifungal activity of saperconazole (R 66 905) in vitro.
Saperconazole, a novel orally active triazole antifungal, inhibited Candida spp., Aspergillus spp. and dermatophyte fungi in vitro. Its minimal inhibitory concentrations for Candida spp. and dermatophytes were relatively high, like those of comparable triazole antifungals, but all of the Aspergillus isolates tested were inhibited by less than 0.1 mg/l. Relative inhibition factors of saperconazole were in the range 31-76% for Candida isolates, 6-18% for Aspergillus isolates and 5-10% for dermatophytes. These figures predict a good inhibitory activity of saperconazole for all the fungi tested, with particularly strong activity against Aspergillus spp. and dermatophytes. Saperconazole inhibited hyphal branch formation in C. albicans at concentrations as low as 10(8) M.
Antifungal Agents↗
Abrogation by glucose of the ATP suppression induced by miconazole in Candida albicans.
Miconazole at 10 mg/l effected rapid (less than 1 min) and substantial (greater than 99%) reductions of intracellular ATP concentrations in buffered suspensions of Candida albicans. This ATP-suppressive effect was mirrored by a rapid reduction in the viable counts of the suspensions. However, the presence of exogenous glucose or fructose (but not several other carbon sources) greatly retarded the ATP-suppressive effect of miconazole. Glucose and fructose could even reverse the suppression when they were added to miconazole-pretreated suspensions. These data indicated that the non-viable cells remained metabolically active. The abrogatory effect of glucose on ATP reduction was optimal between pH 6.5 and 7: it was prevented by fluoride, a known inhibitor of glycolysis, and 2-deoxy-D-glucose could not substitute for glucose, demonstrating that metabolism of glucose was essential for the effect. Two detergents and orthovanadate were much less potent ATP suppressors than miconazole, but the proton pump uncoupler, carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP) was 10 times more active. The results suggest that miconazole may reduce ATP either by uncoupling substrate uptake mechanisms dependent on the fungal membrane proton pump or by inhibition of plasma membrane ATPase.
Adenosine Triphosphatases↗
A morphology index for characterization of cell shape in Candida albicans.
The morphology of Candida albicans cells was determined from their maximum length, maximum diameter and septal diameter in a mathematical ratio, the morphology index (Mi), which usually ranged from approximately 1 for spherical yeast cells to approximately 4 for true hyphae, with elongated yeast cells and pseudohyphae giving intermediate values. Mi could be determined with high reproducibility for C. albicans grown in a variety of environments. The highest mean Mi was seen with cells grown in serum and Eagle's medium at 37 degrees C, the lowest with cells grown in Sabouraud glucose broth at 26 degrees C. Variant strains of C. albicans gave Mi values that remained constant in a variety of growth environments. The Mi facilitated detection of two variants that grew exclusively in the yeast form, one that grew as elongated yeasts but could be induced to form pseudohyphae in serum, and one consistently pseudohyphal variant. Cells with a mean Mi up to 2.5 could be easily separated at septal junctions by mild ultrasonication, whereas cells with a mean Mi greater than 3.5 tended not to separate under these conditions. The chitin content of C. albicans cells was almost twice as great in cells with a Mi approaching 4 as in cells with a Mi close to 1. The wide range of Mi distributions for a single C. albicans isolate in different environments demonstrates that the fungus does not undergo abrupt changes of morphological phase: rather there are continual changes in morphology between spherical yeasts and true hyphae at the extremes. The study shows that Mi can be used reliably in place of subjective descriptions of morphology to indicate the shape of a C. albicans cell. It should facilitate the detection of molecular and cellular markers specific for morphogenesis in the fungus.
Candida albicans↗
Candida species and C. albicans biotypes in women attending clinics in genitourinary medicine.
Yeasts were isolated from two or more anatomical sites in 198 women attending genitourinary clinics on at least two occasions. The yeast biotypes isolated concurrently from the vagina and urethra were the same in 138 (99%) of 140 instances, and 94% of 124 concurrent genital and anal isolates were of matching types, whereas only 75% of concurrent genital and oral isolates were of the same type. Mixtures of Candida spp. or C. albicans biotypes were encountered only five times among 545 yeast-positive samples. In instances where Candida spp. were isolated at successive times from the same site in a patient, the same yeast type was encountered on 97 (87%) of 112 occasions when the interval between samples was less than 15 weeks, and on 19 (66%) of 29 occasions when the interval was 15 weeks or more. These data indicate a tendency to carriage of phenotypically consistent types of Candida among most women attending genitourinary clinics.
Anal Canal↗
Colony variations in Candida species.
One hundred isolates of seven Candida species and three isolates of Saccharomyces cerevisiae were plated on phloxine B agar and examined for variations in the morphology or colour of colonies that developed. Colony variations were found in 9 of 12 C. parapsilosis isolates, 8 of 13 C. tropicalis isolates, 4 of 9 C. krusei isolates and 12 of 30 C. albicans isolates. None of 23 C. glabrata isolates grew on the test medium. Variant colonies often generated further different colony forms on secondary subculture. The rate of production of fimbriate and rhizoid colonies by two C. albicans isolates varied with agar thickness and the nutrient content of the medium. These results suggest that colony variation is a common property among isolates of many Candida species and that strict control of agar medium thickness and composition is essential for reproducible screening of isolates for colony variations.
Candida↗
Biotyping of Candida albicans: results of an international collaborative survey.
An agar plate system for biotyping isolates of Candida albicans was evaluated in four laboratories for 18 coded yeast isolates, each tested in triplicate on duplicate series of agar plates. The results showed that the biotyping system gave excellent intralaboratory reproducibility. However, because the concordance of data among laboratories was poor, the method must be regarded as suitable only for research applications and not for routine use.
Candida albicans↗
Carriage of Candida species and C albicans biotypes in patients undergoing chemotherapy or bone marrow transplantation for haematological disease.
Six hundred and seventy four yeast isolates obtained from routine microbiological screening of 153 patients with haematological disease were identified and Candida albicans isolates biotyped over nine months to determine longitudinal and cross sectional patterns of yeast colonisation. A yeast microflora persisted in many patients despite the routine prophylactic use of oral antifungal agents. Analysis of the yeast species isolated on a cross sectional basis showed that C albicans accounted for 65% of yeasts isolated from the oral cavity but only 45% of the faecal yeast flora. Longitudinal changes in yeast flora occurred significantly more often in faecal samples than in oral samples and significantly less often in sites colonised with C albicans than in sites colonised with other species. No associations were found between the yeasts isolated and the nature of antifungal prophylaxis used, or the extent of a patient's stay in hospital.
Antifungal Agents↗
[Relative inhibition factors: a new approach to the evaluation of antifungal antibiotics in vitro].
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Antifungal Agents↗
Candida concentrations in the vagina and their association with signs and symptoms of vaginal candidosis.
Among 106 women harbouring yeasts in the vagina and with other causes of genital pathology excluded, there was a statistically significant association between numbers of yeasts recovered semi-quantitatively from vaginal swabs and symptoms of pruritus and signs of abnormal vaginal discharge but no association between yeast numbers and other individual symptoms or signs of vaginal candidosis, including patients' own subjective assessment of abnormal vaginal discharge. The presence of yeasts detectable by direct microscopic examination was statistically associated with pruritus, discharge and vaginitis. There was no relationship between numbers of vaginal yeasts and histories of antibiotic or oral contraceptive usage or the stage of the menstrual cycle. Distributions of Candida species and Candida albicans biotypes were not statistically related to any symptoms, signs or other factors. The results of this study suggest that vaginal pathology caused by Candida species may be related to the quantity of the fungus in the vagina and that only pruritus and objectively assessed vaginal discharge are firm clinical indicators of Candida infection.
Candida↗
Effects of azole antifungals in vitro on host/parasite interactions relevant to Candida infections.
Clotrimazole, fluconazole, itraconazole and ketoconazole were tested for their influence on three aspects of host/parasite interactions in the context of Candida infections. None of clotrimazole, itraconazole or ketoconazole had any effect on the adherence of C. albicans to vaginal epithelial cells, in vitro, regardless of whether the drugs were used to pretreat the fungi or the vaginal cells or were added to the fungus/vaginal cell mixture. Clotrimazole pretreatment of polymorphonuclear leucocytes led to a marked suppression of their ability to phagocytose and kill C. albicans, but fluconazole and ketoconazole had no similar effect. None of these three antifungals affected phagocytosis or killing when they were added to the leucocyte candida mixture or when used to pretreat the fungi. Clotrimazole and ketoconazole both reduced proliferative responses of lymphocyte suspensions to mitogens but fluconazole showed no anti-lymphocyte effect. This difference in action against lymphocytes may help to explain the known disparity between the antifungal effects of fluconazole and ketoconazole against C. albicans in vivo and against experimental candida infections in vitro. Clotrimazole effected a suppression of ATP concentrations in lymphocytes but fluconazole and ketoconazole had no similar effects.
Antifungal Agents↗
Activity of cilofungin (LY121019) against Candida species in vitro.
Cilofungin (LY121019) was compared with amphotericin B in vitro for its inhibitory and fungicidal activity against Candida species. In minimal inhibitory concentration (MIC) tests the two compounds showed comparable inhibitory activity against 31 isolates of C. albicans and C. tropicalis. However, cilofungin was by comparison only weakly active against 19 isolates representing the species C. glabrata, C. kefyr and C. krusei, and essentially inactive against 11 isolates representing C. guilliermondii and C. parapsilosis. The inhibitory activity of cilofungin, unlike that of amphotericin B, was reduced in medium containing serum. Relative inhibition factors (RIFs) for the two compounds confirmed the MIC data: RIFs of 85% and more were obtained in tests with species other than C. albicans and C. tropicalis: for the latter two species, RIFs were in the range 41-66%, indicating drug activity comparable to that of systematically active azole compounds. (RIFs for amphotericin B were less than 40% for all isolates.) Cilofungin was generally less fungicidal than amphotericin B, and it was only rarely fungicidal in tests done in medium containing serum. Because of its inhibitory action and its low toxicity, the compound may prove to be therapeutically useful in infections caused by the two most commonly encountered pathogenic Candida species.
Amphotericin B↗
Binding of plasma proteins to Candida species in vitro.
The ability of purified human albumin, fibrinogen and transferrin to bind to Candida species was measured by immunofluorescence. The proteins all bound with high avidity to germ-tubes formed by Candida albicans, but did not bind to blastospores of C. albicans or other pathogenic Candida species, not even to parent blastospores bearing germ-tubes. The extent of binding of the proteins to C. albicans germ-tubes varied between growth media and from germ-tube to germ-tube. Strains of C. albicans that did not form germ-tubes were incapable of binding any of the proteins. There was evidence that purified fibrinogen bound to germ-tubes with higher avidity than albumin and transferrin. When germ-tubes were treated with whole human plasma or serum, indirect immunofluorescence revealed that proteins were bound all over the surface of C. albicans blastospore-germ-tube units, indicating behaviour different from that seen with the purified proteins tested alone or in mixtures. C. albicans cells grown in the presence of azole antifungal agents bound purified plasma proteins in the same way as cells untreated with the drugs. The results of this study suggest that binding of host proteins to the surface of C. albicans may not be a property related directly to virulence of the fungus in vivo.
Antifungal Agents↗