The Chlamydospore of Candida albicans.

Summary:  The chlamydospore of Candida albicans is a disputable growth from the point of view of its development and function. On the basis of light microscopic as well as scanning electron microscopic (SEM) investigations difficulties of distinguishing chlamydospores and their holding structure are discussed by the authors. Attempts are made to draw conclusions from some morphological properties on the ancient, reproductive organ function of the chlamydospores.
Zusammenfassung:  Die Chlamydospore von Candida albicans ist ein Formelement, dessen Entwicklung und Funktion umstritten ist. Auf der Grundlage von licht- und rasterelektronenmikroskopischen Untersuchungen werden die Schwierigkeiten der Unterscheidung der Chlamydosporen und ihrer Trägerapparate von den Autoren diskutiert. Es wird versucht, aus einigen morphologischen und physiologischen Eigenschaften auf die ursprüngliche, reproduktive Organfunktion der Chlamydosporen zu schließen.     

Comparison of phospholipase and proteinase activity in Candida albicans and C. dubliniensis

Although the production of virulence enzymes by Candida albicans has been extensively explored, little attention has been given to the virulence factors of C. dubliniensis. In the present study, an attempt was made to investigate phospholipase activity (Pz value) and secretory aspartyl proteinase production of C. dubliniensis and compare it with C. albicans. None of the 87 C. dubliniensis isolates tested, produced phosholipases whereas, in contrast all the 52 (100%) C. albicans isolates tested demonstrated varying degree of phospholipase activity (Pz value: 0.37-0.74), with 35 (67.3%) of them eliciting a higher phospholipase activity (Pz values between 0.37 and 0.50). Only 32% of the C. dubliniensis isolates exhibited moderate activity (score of 1+) of secretory aspartyl proteinase whereas a vast majority (68%) of them were non-proteolytic. On the contrary, a strong proteinase activity (score of 2+) was observed for 79% of C. albicans while the remaining 21% isolates showed moderate proteinase activity (score of 1+). As phospholipases and aspartyl proteinases of C. albicans are considered important virulence factors, the absence or lowered expression of these enzymes in C. dubliniensis may indicate the less virulent nature of this novel yeast species when compared with C. albicans.     

Diagnostische Bedeutung des Candida albicans abtotenden Faktors*

Zusammenfassung: In der vorliegenden Arbeit wird die Methodik des Nachweises des Candida albicans abtötenden Faktors und dessen Bewertung beschrieben. Die Untersuchung wurde an Seren von Patienten, die durch eine invasive Kandidose gefährdet sind und von gesunden Menschen durchgeführt. Der candidocide Faktor wurde bei gesunden Menschen, aber auch bei Asthmatikern, die mit Kortikosteroiden behandelt wurden, weiter bei Kranken mit Niereninsuffizienz und bei Leukämikera festgestellt Zur wesentlichen Reduktion dieses Faktors kam es bei Kranken mit Tumoren, Leberzirrhose und besonders bei Diabetikern. Diese Patienten sind deshalb gegen die invasive Form der Kandidose anfällig, denn Candida-Zellen können sich in ihrem Blut ungestört vermehren. Bei den untersuchten Kranken wurden auch komplementfixierende und präzipitierende Anti-körper vorgefunden, die nut dem erhöhten Vorkonunen von Candida im Infektionsmaterial korrelierten. Diese immunologische Reaktion spricht auch für die parasitische Wirkung der Candida-Pilze. Summary: Proof and evaluation of the candidacidal factor ist described in the sera of patients compromised of invasive candidiasis as well as in the sera of healthy persons. The candidacidal factor was found in the sera of healthy persons, of patients treated with corticosteroids, of patients with leukaemia and kidney insufficiency. The factor was substantially reduced in the sera of patients with cancer, cirrhosis and especially with diabetes mellitus. These patients are therefore sensitive to invasive candidiasis as the Candida cells can multiply uninhibited in the serum. Complement fixing antibodies as well as precipitins were found in the investigated patients. The antibodies were in correlation with the high Candida colonisation of these persons. This immunological reaction agrees with the parasitic effect of Candida in these cases.     

Scanning Electron Microscopy of Candida albicans Chlamydospores

Summary:  Candida albicans chlamydospores were studied using scanning electron microscopy method. The various relationships of chlamydospore and pseudohyphae were documented as follow: terminal chlamydospore with or without suspensor cell; lateral chlamydospore with or without suspensor cell; terminal chlamydospore pairs with or without suspensor cell; lateral chlamydospore pairs without suspensor cell.
Zusammenfassung:  Die Chlamydosporen von Candida albicans wurden rasterelektronenmikroskopisch untersucht. Die unterschiedlichen Beziehungen zwischen Chlamydosporen und Pseudohyphen werden wie folgt beschrieben: Terminate Chlamydospore mit oder ohne Suspensorzelle; laterale Chlamydospore mit oder ohne Suspensorzelle; terminale Chlamydosporen-Paare mit oder ohne Suspensorzelle; laterale Chlamydosporen-Paare ohne Suspensorzelle.     

Virulence of Candida albicans mutants

Mutant strains of the fungal pathogen Candida albicans blocked in pyrimidine transport and salvage metabolism were tested for virulence in various animal models. The growth rate, germination and proteolytic enzyme production did not correlate with the virulence of the strains. However, a defect in the uridine transport system significantly decreased virulence in murine candidosis, although it had no effect in vaginal candidosis or in a Candida cyst model. It remains unclear whether this is due to the differing host defence mechanisms involved in systemic and superficial mycoses, or to the different requirements of the fungal systems for adherence and tissue invasion in the two types of infection.     

Four cases of Candida albicans infections with isolates developing pink colonies on CHROMagar Candida plates

Candida albicans, the most commonly isolated yeast species, is typically identified by its green colony-colour on CHROMagar Candida plates. We here report four cases of Candida albicans infections, in which the initial identification was non-albicans isolates due to a clear pink colour of the colonies on CHROMagar Candida plates. However, classical phenotypic criteria, biochemical assimilation pattern and molecular characterisation identified all four isolates as C. albicans isolates.     

The Effect of Antimycotics on Secretory Acid Proteinase of Candida albicans

Summary

The effect of antimycotics on secretory aspartate (acid) proteinase, a virulence enzyme of Candida albicans, was investigated.

The conditions of the study were such as to induce proteinase production in the stationary phase of growth (25-40 hours), when no antifungal tested, except the polyene derivative methyl partricin, significantly reduced the viability of the culture.

Among azole derivatives, fenticonazole (FZ) but not miconazole, fluconazole or ketoconazole, exerted strong inhibition on proteinase, in typical dose-diphasic pattern, (0.01 μg/ml; 1-10 μg/ml). 5-fluorocytosine (5-FC) was also inhibitory at a dose interval 1-10 μg/ml. In all cases, the inhibition concerned the synthesis of the enzyme rather that its activity as suggested by the results of comparative ELISA, SDS-PAGE and spectrophotometric methods of proteinase detection.

Finally, the inhibition of proteinase production by FZ and 5-FC mainly reflected the effect of these antimycotics on general protein synthesis.     

Stimulierung der Filamentbildung von Candida albicans durch Kammerwasser

Zusammenfassung:  Kammerwasser von Kaninchen stimuliert das filamentöse Wachstum von Candida albicans in stammabhängiger Weise. Die Zugabe von Kammerwasser zu Blastosporen des Stammes DSM 70010 in Nährbouillon und Inkubation bei 37°C für 18–24 h führt ebenso zur Filamentbildung wie die Inkubation der Blastosporen mit Blutse-rum. Bei Stamm CBS 2730 ergibt nur Serum Filamentwachstum, nicht aber Kammerwasser. Falls im Verlauf einer Candida -Keratitis die Descement'sche Membran durchwachsen wird, könnte die Filamentstimulation durch Kammerwasser klinische Relevanz erlangen.
Summary:  Aqueous humor of rabbit eyes stimulates the filamentous growth of Candida albicans in a strain-dependent manner. Addition of aqueous humor to blastospores of strain DSM 70010 in nutrient broth and incubation at 37°C for 18–24 h yields filaments which are comparable to filaments after incubation of blastospores with blood serum. In strain CBS 2730 serum promotes the formation of filaments but not aqueous humor. If in the course of Candida keratitis the fungus penetrates Descement's membrane, the filamentation in aqueous humor may influence the outcome of the mycosis.     

Differences in patient risk factors and source of candidaemia caused by Candida albicans and Candida glabrata

There is an increasing frequency of candidaemia caused by Candida glabrata which has decreased in vitro susceptibility to fluconazole. Differences in risk factors for candidaemia caused by C. glabrata and C. albicans have not been formally evaluated in a diverse patient group. We performed a retrospective study of adult inpatients from January 1, 2003 to April 30, 2008 with C. glabrata and C. albicans candidaemia at a single tertiary care centre in Detroit, Michigan to evaluate for differences in risk factors and presumed source of infection in these groups. Patients’ underlying conditions, risk factors and source of infection (probable or definite) were compared. Among 119 patients, 80 (67.2%) were C. albicans and 39 (32.8%) C. glabrata. Using logistic regression analysis, patients with C. glabrata infection were more likely to have diabetes mellitus (OR 2.43; 95% CI, 1.06–5.54) and abdominal source of infection (OR 4.53, 95% CI, 1.72–11.92). Mortality rates in the two groups were similar. Patients with C. glabrata candidaemia are more likely to be diabetic and have an abdominal source of infection compared with patients with C. albicans.     

The involvement of physico-chemical interactions in the adhesion of Candida albicans and Candida dubliniensis to epithelial cells

Candida albicans and Candida dubliniensis are two pathogenic yeasts particularly hazardous to immunocompromised patients. Adhesion of yeast cells to epithelium is considered one of the virulence factors and its study is of major importance. The main aim of this study was the comparison of the influence of physico-chemical properties on the adhesion of C. albicans and C. dubliniensis to epithelium. Two strains of each Candida species were used in the adhesion assays to HeLa cells. Adhered cells were enumerated by direct microscopic images observation. Yeast cell surface tension parameters and degree of hydrophobicity were determined by contact angle measurement. Pseudohyphae and hyphae formation was analysed by scanning electron microscopy. Yeast cells presented no statistical differences concerning their physico-chemical surface properties. However, the extent of adhesion to epithelium was different among the four strains. As general conclusion, yeast adhesion to epithelium seems to be strain-dependent and not directly correlated with pseudohyphae formation.     

Action of the Ketoconazole-Alkylaminoethylglycine Combination on Candida albicans

Summary

High concentrations of ketoconazole (Ktc) exhibit poor antimicrobial activity in microbicidal test.

Alkylaminoethylglycine (AAEG), an amphoteric surfaceactive agent, employed in subinhibitory concentrations, can enhance the action of ketoconazole. The Ktc-AAEG combination causes a higher rate of potassium ion release compared to both drugs separately.

The increased ketoconazole activity may be ascribed to the membrane damage indicated by increased permeability to potassium ions.     

Growth of Candida albicans on the stratum corneum of diabetic and non-diabetic patients

We have used a novel approach to in vitro culture of Candida albicans on cyanoacrylate skin surface strippings. It appears that with this model yeasts and hyphae grew on large surfaces of stratum corneum. The area of extension of the fungal growth was larger on stratum corneum taken from diabetic than from non-diabetic volunteers.     

Isolierung von Antigenfraktionen aus Candida albicans

In der Literatur existieren eine Vielzahl von Methoden zur Extraktion von Antigenen aus dem Zellinhalt und der Zellwand von Candida albicans, von denen jedoch nur wenige befriedigende Ergebnisse liefern, da die Qualität der extrahierten immunologischen Bestandteile bei einigen Verfahren durch Strukturveränderungen beeinträchtigt und in der Regel nur ein Teil der Antigene dargestellt wird.—Neben der sachgerechten Extraktion stellen die weitere Reinigung und Fraktionierung Möglichkeiten zur Gewinnung von chemisch exakt definierten C. albicans-Antigen mit Mannan-, Protein- oder Mannan-Proteincharakter dar.
Mannane gewinnen wir durch eine milde Hydrolyse mit β-Naphthol und anschließender Fällung mit FEHLINGscher Lösung. Neutrale und saure Mannane lassen sich durch eine Cetavlonbehandlung voneinander trennen. Proteinantigene werden nach mechanischer Zerstörung der Hefezellen und Fällung mit Ammoniumsulfat dargestellt.

Summary

Numerous methods for the extraction of somatic and cell wall antigens from Candida albicans are described in the literature, but only a few of these produce satisfactory results, since the quality of the extracted immunological components is impaired by structural modification in the case of some methods and, as a rule, only a part of the antigens are obtained. Apart from correct extraction, further purification and fractionation represent other opportunities for obtaining chemically precisely defined. C. albicans antigens of a mannan, protein or mannan-protein character. Mannans are obtained by mild hydrolysis with ß-naphthol and subsequent precipitation by F ehling's solution. Neutral and acidic mannans can be seperated by treatment with Cetavlon. Protein antigens are obtained by the mechanical destruction of the yeast cells and precipitation by ammonium sulphate.     

Standardized molecular typing of Candida albicans strains

Summary. A method is presented for the standardization of Candida albicans DNA fingerprinting, which is based on Southern hybridization of Eco RI-digested chromosomal DNA with the moderately repetitive DNA element CARE-2 and the subsequent rehybridization of the blots with a molecular size marker also included in each DNA sample. This method resulted in extremely precise alignment of all strain-specific CARE-2 hybridization patterns, even when analysed on different gels, and will enhance the accuracy of genetic relationship determinations in epidemiological studies including large numbers of strains.
Zusammenfassung. Zur Standardisierung des DNA-Fingerprinting von Candida albicans wurde eine Methode entwickelt, die auf der Southern Hybridisierung Eco RI-gespaltener chromosomaler DNA mit dem mittelrepetitiven DNA-Element CARE-2 und der darauffolgenden Rehybridisierung der Blots mit einem auch in den Proben enthaltenen molekularen Größenmarker beruht. Dies resultierte in einer äußerst präzisen Größen-bestimmung der hybridisierenden Fragmente, so daß alle stammspezifischen CARE-2-Hybridisierungsmuster exakt verglichen werden konnten, auch wenn die Isolate auf verschiedenen Gelen analysiert wurden. Die Methode erhöht die Genauigkeit der Bestimmung genetischer Verwandtschaftsbeziehungen in epidemiologischen Untersuchungen, in denen eine große Anzahl von Stämmen analysiert wird.     

Mode of action of ciclopiroxolamine on Candida albicans

Candida albicans is a common pathogen causing both superficial and invasive mycoses. The hydroxypyridone ciclopiroxolamine belongs to antimycotic drugs used for treatment of superficial mycoses. Whereas the mode of action of other antimycotics, for example the azoles, is well known, the specific action of ciclopiroxolamine is poorly understood. There are hints, that ciclopiroxolamine acts as a potential chelating agent and influences some cellular processes by chelating metal ions. Consequently, the antimycotic effectiveness of ciclopiroxolamine could be due to a general reduced viability of the fungus, or due to a higher sensitivity of a fungus against the human immune system as well as due to a reduced capability to produce some specific virulence factors that are indispensable for infection. Nevertheless, iron metabolism seems to play a major role in its effect.     

Zur Korrelation von Biotyp und Antimykotika-sensibilität bei Candida albicans. On the Correlation of Biotype and Antimicrobial Susceptibility in Candida albicans

Zusammenfassung: 54 rezente Candida albicans-isolate von Haut und angrenzenden Schleimhäuten wurden zunächst auf Grand der von Odds und Abbott 1983 (23) angegebenen Eigenschaften biotypisiert. Anschließend wurde ihre Antimykotikaempfindlichkeit nüt Hilfe von Agardilutions- und Mikrodilutionstest untersucht. Insgesamt fanden sich 42 verschiedene Biotypen, die im häufigsten Falle viermal vertreten waren. Die minimalen Hemmkonzentrationen (MHK) von 5-Fluorcytosin (5FC) schwankten zwischen 0,016 und mehr als 128 mg/l. Die IC₃₀-Werte nach Johnson et al. 1984 (17) reichten von 0,25 bis mehr als 64 mg/l. Bei Ketoconazol lagen die MHK-Werte zwischen 32 und 128 mg/l. Wie angesichts dieser geringen Bandbreite nicht anders zu erwarten, fand sich bei diesem Antimykotikum keine klare Korrelation zwischen Biotyp und minimalen Hemmkonzentrationen. Bei 5FC ließ sich demgegenüber eine derartige Korrelation innerhalb der Biotypengruppen 1 und 3 nachweisen: Innerhalb der Gruppe 1 erwiesen sich die mit den Kodenummern 4 und 5 als besonders resistent. Innerhalb der Gruppe 3 bestand ein entsprechender Zusammenhang mit der Kodenummer 7. Summary: 54 recent clinical mucocutaneous isolates of Candida albicans were differentiated using several different characteristics as described 1983 by Odds and Abbott (23). In addition antimicrobial susceptibility testing was performed using both the agardilution and microdilution method. 42 different biotypes were found, the most frequent one turning up four times. The minimum inhibitory concentrations (MIC) of 5-fluorocytosine (5FC) ranged from 0.016 to more than 128 mg/l. The IC₃₀ values according to Johnson et al. 1984 (17) lay between 0.25 and more than 64 mg/l. With ketoconazole the MICs ranged from 32 to 128 mg/l. As could be exspected from this small range no clear correlation could be demonstrated between biotype and MIC with this antimycotic. With 5FC, however, there was a correlation within the biotype groups 1 and 3: within group 1 the strains carrying the code numbers 4 and 5 were especially resistent to 5FC. Within group 3 this especially was the case with code number 7.     

Interest of biotyping Candida albicans in chronic vulvovaginitis

Chronic vulvovaginitis due to Candida albicans is a major clinical problem for the physician. Although new antifungal drugs are now available, the therapeutic approach of this disease remains disappointing. The aims of this study were two-fold. First, we wanted to evaluate the reliability of a single sampling performed by most clinicians in verifying if the yeast infects the entire genital mucosa or a preferential site and, second, to biotype the strains recovered in order to see if more than one strain are responsible for the infection. We found, in 18 patients suffering from vaginal candidosis, that the entire genital mucosa was infected by the yeast and the strain recovered from the different genital sites in a single patient was the same in 100% of the cases. Only 1.4% of the samples were negative. In addition, we biotyped the strains obtained from the gastrointestinal tract of these patients to evaluate this site as a potential source of infection. We obtained gastrointestinal tract samples for 15 of the 18 patients and we could identify C. albicans in 100% of the cases. Furthermore, 73.3% of the patients harboured the same strains of C. albicans in the gastrointestinal tract as in the vagina.     

Regulation of the Direct Fungicidal Action of Miconazole against Candida albicans ATCC 26790/Die Regulation der direkten fungiziden Wirkung von Miconazol auf Candida albicans ATCC 26790

Summary: The direct lethal action of ł 10⁻⁵ M miconazole against Candida albicans ATCC 11651 depends upon, and is therefore regulated by, growth phase, pH, and whether any miconazole is present during lag phase when susceptibility develops. Certain of these studies were recently extended to C. albicans ATCC 26790 with nearly identical results, suggesting that such regulation is a general phenomenon.
Zusammenfassung: Die direkte letale Wirkung von ≥ 10⁻⁵ M Miconazol gegen Candida albicans ATCC 11651 hängt ab und wird daher reguliert von der Wachstumsphase, dem pH-Wert und davon, ob überhaupt Miconazol während der lag-Phase anwesend ist, in der sich die Suszeptibilität entwickelt Einige dieser Untersuchungen wurden jüngst auf Candida albicans ATCC 26790 erweitert mit fast identischen Resultaten, was zu der Vorstellung führt, daß diese Regulation ein allgemeines Phänomen ist.     

Adherence ability of Candida africana: a comparative study with Candida albicans and Candida dubliniensis

In this study, we compared the adherence ability to human Hela cells and biofilm formation of three closely related Candida yeast. In our experiments, Candida africana showed poor adhesion ability to human Hela cells and the absence of biofilm formation on polyvinyl chloride strips. Conversely, Candida albicans and Candida dubliniensis formed mature biofilms and stable attachment to Hela cells. To our knowledge, this is the first comparative study reporting data on biofilm formation and adherence to human Hela cells by C. africana.