Chlamydospore production in candida albicans

Summary A review of the literature correlated with laboratory studies of the influence of carbon source, temperature, and pH on chlamydospore formation, substantiate the enzymatic hypothesis of morphogenesis inCandida albicans.     

Phosphate directed Y-M variation in candida albicans

Summary The influence of pH, O-R potential, dextrose/inorganic phosphate ratio, nitrogen source, and various cations on filamentation ofCandida albicans when grown on phosphate enriched Sabouraud Dextrose Agar (Difco) at 37° C were investigated. The dextrose/phosphate ratio apparently plays a key role under these conditions. It is postulated that magnesium ion trapped within the cell by excess polyphosphate formation leads to filamentation.Supported by U.S.P.H.S. E-1700 and U.N.C. Research Council 324-ALU-1 (360).     

Lytic action of lysozyme on candida albicans

Yeast cells ofCandida albicans in lysozyme glucose solution were incubated in a 37° C water bath for 6 hours, spread on the surface of a Sabouraud's agar plate and incubated at 37° C for 18–24 hours. Scattered small colonies were seen on the agar surface compared with the thick full growth of the control culture incubated without lysozyme. Twenty-one strains of 6 standard Candida species of human isolation other thanCandida albicans; C. stellatoidea, C. tropicalis, C. pseudotropicalis, C. krusei, C. parapsillosis, C. guilliermondii, showed essentially the same results asCandida albicans. A constant quantity of lysozyme caused destruction of Candida cells to an equal degree, regardless of varied concentrations of glucose. Dilution of lysozyme greater than 100 times the original (5 mg/ml) showed the same degree of candicidal activity, however, was dependent on the presence of minute amounts of glucose. The presence of NaCl prevented the lysis of Candida by lysozyme in various solutions. Candida cells with lysozyme in glucose solution was incubated for 6 hours in a 37° C water bath. Microscopic observations revealed drastic changes in cell morphology. Most of the cells were swollen, degenerated and some completely destroyed. The gram-positive characteristics of Candida cells changed to gram-negative. The combined activity of lysozyme with complement and antibody may play an important role in the protection against Candidiasis in vivo.

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Zusammenfassung Candida albicans-Zellen sind in Lysozyme-glukose-Lösung bei 37° C in Wasserbad für 6 Stunden bebrütet worden; sie sind dann an der Oberfläche von Sabouraud's Agarplatten ausgestrichen und bei 37° C für 18–24 Std. bebrütet worden. Zerstreute, kleine Kolonien sind an der Agarfläche erschienen, im Vergleich mit dem dicken, vollen Wachstum der Kontrolkultur, die ohne Lysozyme bebrütet worden ist. Einundzwanzig Stämme von sechs Standard-Candida Arten aus menschlichen Quellen außerC. albicans: d.h.C. stellatoidea, C. tropicalis, C. pseudotropicalis, C. krusei, C. parapsillosis, C. guilliermondii, zeigten im wesentlichen dasselbe Ergebnis wieC. albicans. Eine konstante Quantität von Lysozyme bewirkte die Zerstörung der Candida-Zellen zu gleichem Grade ohne Rücksicht auf die wechselnde Konzentration der Glukose. Eine großere Verdünnung von Lysozyme als die hundertfache des Originals (5mg/ml) zeigte denselben Grad der candicidalen Aktivität, jedoch war sie von der Gegenwart einer kleinsten Menge von Glukose abhängig. Die Gegenwart von NaCl hat die Lyse von Candida durch Lysozyme in verschiedenen Lösungen verhindert. Candida-Zellen waren mit Lysozyme in Glukoselösung für 6 Std. in Wasserbad bei 37° C bebrütet. Mikroskopische Beobachtung hat einen großen Wechsel in der Zellmorphologie enthüllt. Die meisten Zellen waren geschwollen, degeneriert, und manche völlig zerstört. Die grampositive Eigenart der Candida-Zellen wechselte in die gram-negative. Die vereinigte Aktivität von Lysozyme mit Komplement und Antikörper mag eine wichtige Schutzrolle gegen Candidiasis in vivo spielen.

     

Oral ketoconazole therapy for experimental candida albicans keratitis in rabbits

Oral ketoconazole (100 mg daily for 3 weeks) markedly reduced the severity of experimental Candida albicans keratitis in a group of 10 rabbits. Clinical scores of affected eyes were statistically significantly lower in the treated group than in a control group of 10 untreated rabbits. All cultures of corneal scrapings in the treated eyes were negative on the 15th day after the inoculation, whilst three positive cultures were still obtained on the 21st day in the control animals. Histopathological examination of eyes from treated and untreated rabbits showed great differences in the intensity of inflammatory changes in the two groups.     

The in vitro interactions of candida albicans with nonspecific serum proteins

Conclusions Iron has a pivotal role in serum inhibition and filamentation. That there may be an inverse relationship between inhibition and filamentation is suggested by the observations that free serum iron abolishes inhibition and stimulates filamentation.Evidence indicates that filamentation results from the interaction of substrates, growth conditions, and temperature, rather than from a single factor. Filamentation occurs during clumping and appears to be necessary for the manifestation of this later process, but any further relationship is unknown.Opsonins seem to be a part of the complement system or their function at least is dependent upon complement activity. Their interaction with surface antigens form chemotactic stimulants but their contribution to the phagocytic destruction of C. Albicans is unclear. All of these serum-Candida interactions are in vitro observations. Although opsonization and phagocytosis probably play a vital role in the in vivo defenses against invading Candida, the contribution of these other interactions to host resistance remain unknown.To prevent the repetitious use of terms germ tube formation, germination, filamentation, and Y M conversion will be used interchangeably. All these terms have been used by various authors to describe this morphological event.     

Development and evaluation of a rapid identification test for candida albicans

Summary A new technique for the rapid identification ofC. albicans has been developed and evaluated. This yeast can be identified in one hour by the formation of germ tubes after inoculation in 1/2 ml of human or animal plasma, and commercial plasma substitutes.C. albicans also forms germ tubes within 2 to 4 hours after inoculation in human serum and incubation at 37° C.Filamentation ofC. albicans in these blood derivatives is a reliable method for the identification of this yeast. It is more rapid than the assimilation and fermentation sugar tests and chlamydospore formation.Assimilation and fermentation sugar tests are used to identify those isolates ofCandida that fail to produce filaments in plasma or serum.     

The pathological activity of metabolic products of candida albicans on newborn mice

Summary Concentrated filtrates ofCandida albicans have an inhibiting effect on the growth of newborn mice. Occasionally, this inhibition of growth is very distinct and the clinical picture corresponds to human progeria.Increased dosages of subcutaneous injections of filtrates did not increase the frequency of appearance of distinctly retarded growth in mice, but the mice showed a great area of baldness.In the number of mice, which did not show progeria, there were degenerative changes in liver and kidneys morphologically suggesting glycogenosis. The same type of changes were also observed when contents of disruptedC. albicans cells were injected into newborn mice. In the later case there was positive histochemical staining for the deposits of glycogen.The induction of pathological changes through fungus filtrates is a newly described biological phenomenon, which may play a greater role in pathology.     

A glutinous rice culture medium for demonstration of chlamydospores of candida albicans

Thirty-four recent isolates ofCandida albicans from clinical material were cultured on glutinous rice agar at 21 pH values ranging from 2.2 to 11.9. After incubation at 25°C all isolates produced chlamydospores on this medium at pH values from 6.6 to 8.0 with an optimum pH of 7.1. Nineteen stock cultures and all recent isolates ofCandida albicans were used to compare the new glutinous rice agar with 9 other culture media recommended for chlamydospore formation. The results indicated that the new medium was superior in terms of (1) economy, (2) rapid production of chlamydospores, (3) transparency and (4) ease of investigation by direct microscopic examination.

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Zusammenfassung Vierunddreißig jüngst isolierte Stämme vonCandida albicans aus klinischem Material sind auf Glutin-Reisagar innerhalb 21 pH-Werte vom 2.2 bis 11.9 gezüchtet worden. Nach Inkubation bei 25°C haben alle Stämme auf diesem Medium bei den Werten von pH 6.6 bis 8.0 Chlamydosporen produziert mit dem Optimum bei pH 7.1. Neunzehn Stammkulturen und alle jüngst isolierten Stämme vonC. llbicans sind verwendet worden um den neuen Glutin-Reisnährboden mit neun anderen, empfohlenen Nährböden fur Chlamydosporen-Produktion zu vergleichen. Die Ergebnisse zeigten, daß der neue Nährboden in folgenden Beziehungen vortrefflicher war: 1) Wirtschaftlichkeit; 2) rasche Chlamydosporen-Produktion; 3) Durchsichtigkeit; 4) Leichtigkeit bei direkter mikroskopischer Untersuchung.

     

Pathological observations in experimental candida infection of sensitized guinea pigs

Guinea pigs immunized intramuscularly with heat-killed or viable Candida albicans were infected intracutaneously with C. albicans. Animals with negative delayed hypersensitivity against C. albicans antigen showed similar lesions with non-immunized controls. Delayed hypersensitivity-positive guinea pigs, which were detected in the animals immunized with heat-killed C. albicans in CFA and IFA, demonstrated a delay of the resolution of the inflammatory tissue reaction and, in the animals immunized with C. albicans in CFA, developed a granuloma.These results suggest that both humoral and cell-mediated immunities do not play a significant role for protection against candidiasis and at a late stage of infection, cell-mediated immunity may play a secondary role of the enhancement of resistance to candida infection associated with granuloma formation.     

Differential binding of lectins IL-2 and CSL to candida albicans and cancer cells

The demonstration that interleukin 2 (IL-2) is a lectin specific for oligomannosides allows to understand a new function for this cytokine: as a bifunctional molecule when bound to its receptor ss, IL-2 associates the latter which the CD3/TCR complex, interacting with oligosaccharides of CD3 through its carbohydrate-recognition domain (Zanetta et al. , 1996, Biochem. J., 318, 49-53). This induces the tyrosine phosphorylation of the IL-2R beta by ++p56(lck) , the first step of the IL-2-dependent signaling. Since this specific association is disrupted in vitro by oligomannosides with five and six mannose residues, we made the hypothesis that pathogenic cells or microorganisms could bind IL-2, consequently disturbing the IL-2- dependent response. This study shows that the pathogenic yeast Candida albicans (in contrast with nonpathogenic yeasts) binds high amounts of IL-2 as did cancer cells. In contrast with cancer cells, yeasts do not bind the Man6GlcNAc2-specific lectin CSL, an endogenous "amplifier of activation signals" (Zanetta et al. , 1995, Biochem. J., 311, 629-636).      

Characterization of binding of human fibrinogen to the surface of germ-tubes and mycelium of candida albicans

The binding of human fibrinogen to germ-tubes and mycelium of Candida albicans, forms usually found in infected tissues, was studied in vitro by an immunofluorescence assay. Binding was quantified by using 125I-labelled fibrinogen. The degree of binding differed according to the morphological form of the fungus. Binding relative to that of the yeast form was greater for mycelium (12-fold) than for germ-tube (7.7-fold). Pretreatment of yeasts with fragments D and E (terminal degradation products of fibrinogen) before fibrinogen binding showed that fragment D possessed a higher affinity for C. albicans than fragment E. Binding of fibrinogen was diminished when C. albicans was pretreated with 2-mercaptoethanol alone or in combination with pronase, or pretreated with alpha-mannosidase or trypsin. Binding was not decreased by pretreatment with pronase alone or chitinase. Inhibition experiments using C. albicans dialysed culture filtrate, C. albicans mannan, chitin, sugars or amino sugars were done by preabsorbing the fibrinogen with each of the above mentioned compounds. C. albicans dialysed culture filtrate inhibited the binding more strongly than C. albicans mannan. However, fibrinogen binding to C. albicans was not significantly reduced by mannose, several other sugars or chitin. These studies demonstrate the existence of a fibrinogen-binding factor (FBF) strongly associated with the surface of germ-tube and filamentous forms of C. albicans, and indicate a possible role for FBF in the pathogenicity of C. albicans.