Intercellular matrix in colonies of Candida.

The histochemistry and fine structure of typical colonies of six species of Candida were studied, using a total of 31 clinical isolates. The colonies consisted of viable and degenerate cells which lay in an intercellular matrix. This matrix was made up of amorphous, granular, and fibrillar components, the relative proportions and total amount of which varied from species to species. The cells of all species were surrounded by a zone of homogeneous amorphus material, which may be a highly cross-linked carbohydrate. This separated intact cells from irregularly distributed granular debris derived from the cytoplasm of degenerate cells. Focal cellular degeneration and associated granular debris were present within the colonies of all species and were most common in the surface layers of cells of colonies of C. albicans and C. tropicalis. The large amounts of intercellular matrix in this region formed a surface coat on colonies of these two species. Intercellular strands of cell wall material, and to a lesser extent other membranous elements from degenerate cells, formed a prominent fibrillar meshwork in the colonies of C. albicans and C. tropicalis, but were less common in those of C. pseudotropicalis and C. guilliermondii and seldom seen in those of C. parapsilosis and C. krusei.     

Reduction of potassium tellurite by Candidas

Summary A technique for observing the reduction of potassium tellurite byCandidas was developed. Various species of these yeasts reduce it at different concentrations, but that which is most useful for differentiation is 0.02 % added to Sabouraud dextrose agar basal medium. Of the yeasts studied,C. albicans, C. parapsilosis andC. tropicalis all reduced potassium tellurite to the concentration mentioned before, while the growth ofC. krusei, C. parakrusei andC. pseudotropicalis was inhibited. Without exception,C. pseudotropicalis reduced this salt at lower concentrations. The two strains ofC. guilliermondii tested gave contradictory results: one of them grew and reduced potassium tellurite, while the growth of the other was inhibited.Professor of Microbiology.     

Flocculation phenomenon of Candida albicans by lysozyme

Young colonies of Sabouraud's glucose agar room temperature culture ofCandida species from human isolation were suspended in distilled water. The suspension was mixed with a solution of lysozyme and incubated in a 37° C water bath. Within 3–5 hours, various species ofCandida cells showed flocculation to varying degrees which occurred at varying periods of onset. Among sevenCandida species,Candida albicans andCandida stellatoidea showed the strongest flocculation, earliest onset and most solution clarity than did any other species.Candida stellatoidea was indistinguishable fromCandida albicans in its degree of flocculation, and in the clarity of solution.Candida species may be arranged in the following order according to their decreasing positivity in flocculation:

1. Candida albicans
2. Candida stellatoidea
3. Candida tropicalis
4. Candida krusei
5. Candida pseudotropicalis
6. Candida parapsilosis
7. Candida guilliermondii
8. Saccharomyces species may be placed afterCandida guilliermondii.

It seems possible to separate theCandida species into 3 groups by the rate of flocculation, and clarity of solution. Group I.Candida albicans andCandida stellatoidea. Group II.Candida tropicalis, C. krusei andCandida pseudotropicalis. Group III.Candida parapsilosis andCandida guilliermondii. Saccharomyces specimens (S. cerevisiae and others) were placed after group III.     

Differentiation of pathogenic species of Candida by their recovery characteristics following ultraviolet irradiation

Each of seven pathogenic species of Candida exhibits a unique pattern of light and dark recovery responses to ultraviolet irradiation. C. guilliermondii, C. parapsilosis and C. pseudotropicalis photoreactivate whereas C. albicans, C. krusei, C. stellatoidea and C. tropicalis do not. Within eachof these groups, individual species are distinguishable by whether or not they express differential dark recovery during postirradiation growth at 25 C or 37 C on oxidative vs fermentative carbon sources, on inorganic vs amino acid nitrogen sources or in the presence rather than absence of ergosterol. Equivalent recovery patterns are obtained for species of Candida and the ascosporogenous species which are their corresponding perfect forms. These observations indicate strongly that the postirradation recovery is a reliable, species-specific characteristic of yeasts.These studies were added in part by a contract (AT11-1)-1772 with the U.S. Atomic Energy Commission.     

Identification of Candida isolated from the cutaneous candidiasis by the combined use of confirmatory medium and slide agglutination with monofactorial antibodies

Forty strains ofCandida and one ofTorulopsis were isolated from patients with cutaneous candidiasis. The isolates comprised 29 strains ofC. albicans, 7 strains ofC. tropicalis, 2 strains ofC. guilliermondii, and one each ofC. parakrusei, C. lipolytica, andT. famata were identified by the ordinary method. Besides the common pathogenC. albicans, a few other species ofCandida may be etiologic organisms of cutaneous candidiasis. These strains were re-examined by combined use of sucrose agar slants and slide agglutination tests with IgG monofactorial antibodies as a rapid identification method, especially for determining serotypes ofC. albicans. The new method was useful and reliable for rapid identification ofC. albicans and related species. All strains ofC. albicans isolated from skin lesions proved to be standard serotypes ofC. albicans.

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Zusammenfassung Vierzig Stämme vonCandida und eins vonTorulopsis wurden aus Kranken mit kutanen Candidamykosen isoliert. Neunundzwanzig Stämme vonC. albicans, 7 vonC. tropicalis, 2 vonC. guilliermondii, und je einer vonC. parakrusei, C. lipolytica undT. famata wurden mit dem ordinären Methode identifiziert. Außer dem gewohnlichen Erreger,C. albicans, konnten auch ein Paar andere Spezies vonCandida als den Erreger betrachtet werden. Sechsunddreißig Stämme vonC. albicans undC. tropicalis wurden mit der von uns verbesserten kombinierten serologischen und biologischen Methode untersucht, besonders um den Serotypus vonC. albicans festzusetzen. Die neue Methode war gut und zuverlässig als die rapide Identification vonC. albicans und verwandten Spezies. Alle aus der Hautläsion isoliertenC. albicans waren der in Japan allgemeine Serotypus vonC. albicans.

     

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.

     

Antifungal activity of some mediterranean algae

Summary The antifungal activity of 15 mediterranean algae species on some dermatophyte strains (Epidermophyton floccosum, Microsporum canis, M. gypseum and Trichophyton mentagrophytes) and pathogenic yeasts (Candida albicans, C. guillermondii, C. krusei, C. tropicalis and Torulopsis glabrata) has been tested following a modification of Aubert's technique.Among the algae species studied, Falkenbergia rufolanosa is the most active in front of all the fungi tested.     

The morphology of colony variants of three species of Candida.

The colonies of 12 isolates of 3 Candida spp. with variant colony forms were studied by scanning and transmission electron microscopy. Small colonies were formed by 4 isolates each of C. albicans and C. parapsilosis and by 1 of C. tropicalis. These had an abnormally high proportion of degenerate yeast cells with an associated increase in granular cytoplasmic material intercellularly. The increased matrix in these small colonies formed a thick superficial coat over the organisms. Rough colonies were formed by 1 isolate each of C. albicans, C. tropicalis and C. parapsilosis. The convoluted regions of these colonies contained many pseudohyphal cells but few degenerate cells and little granular or fibrillar material in their intercellular matrices. The shape of colonies of Candida spp. may be altered by variations in the viability or the morphology of the organisms.     

Candidaemia in cancer patients and in children in a neonatal intensive care unit

The species most frequently found in the group of neonates wasC. parapsilosis, its incidence reaching 48%. Other yeasts isolated from blood wereC. albicans (41%),C. tropicalis (7%),C. krusei andC. pseudotropicalis (2% each). Six yeast species (C. albicans 44%,C. parapsilosis 28%,C. tropicalis 11%,C. krusei 8%,C. guilliermondii 6%,C. lusitaniae 3%) were detected in cancer patients. The presence of an intravenous catheter as a possible risk in the development of candidaemia was identified in all neonates and in 69% of cancer patients.C. krusei candidaemia was associated with prophylactic fluconazole therapy.     

Adherence of Candida species to fibrin clots in vitro

The adherence of six Candida species to fibrin clots was studied using a simple, in vitro technique. Yeast suspensions were incubated with fibrin clots and the number of adherent organisms quantified as follows: after washing, the clots were subjected to vortex mixing and the number of CPU's which subsequently grew on Sabourauds medium were counted. Adhesion was directly proportional to the concentration of Candida species in the suspension (r=0.99 p<0.001). C. albicans and C. tropicalis exhibited marked adherence whereas C. krusei, C. gulliermondi and C. glabrata adhered less readily. C. parapsilosis was intermediate in its ability to adhere.     

A method for the rapid identification of pathogenic yeast-like microorganisms

Summary A new rapid diagnostic method for the identification of pathogenic yeast-like microorganisms is described. By this method in the course of one week these genera can be identified:Candida, Torulopsis, Rhodotorula, Trichosporon, Geotrichum and seven species often found in infectious material, of the genusCandida: C. albicans, C. tropicalis, C. pseudotropicalis, C. krusei, C. guilliermondii, C. pelliculosa andC. parapsilosis.     

The incidence of candidiasis amongst the asymptomatic female students of the University of Jos,Nigeria

A survey was carried out on the incidence of candidiasis amongst the asymptomatic female students of University of Jos. One hundred and three students were selected at guided random. Their first stream urine samples were collected with the aid of sterile McCarthney bottles. The deposits of the centrifuged urine samples were plated out on sabouraud's dextrose agar (SDA) fortified with antibiotics (penicillin G and streptomycin). A total number of 42 positive Candida cases were obtained. This represented 40.78% of the total samples (103) examined. The Candida species isolated included C. albicans, C. glabrata, C. guilliermondi, C. parapsilosis, C. pseudotropicalis, C. stellatoidea, C. tropicalis and C. viswanathii. C. albicans and C. tropicalis were more predominant than the other species. C. albicans had 38.10% frequency of occurrence while C. tropicalis had 21.43% occurrence. The least percentage occurrence was recorded for C. viswanathii which had 2.38%. There were significant relationships between the incidence of candidiasis and the perdisposing factors like drug administration (antibiotics and contraceptive pills), cases of pregnancy and previous cases of urinogenital tract infection. Neither the marital status nor the age groups of the test female students had significant effects on the incidence of this disease. The pH values of the infected urine samples had a significant effect on the incidence of the disease.     

In vitro activity effects of combinations of cephalothin, dicloxacillin, imipenem, vancomycin and amikacin against methicillin-resistantStaphylococcus spp. strains

Background

CHROMagar Candida (CaC) is increasingly being reported as a medium used to differentiate Candida albicans from non-albicans Candida (NAC) species. Rapid identification of NAC can assist the clinician in selecting appropriate antifungal therapy. CaC is a differential chromogenic medium designed to identify C. albicans, C. krusei, and C. tropicalis based on colony color and morphology. Some reports have proposed that CaC can also reliably identify C. dubliniensis and C. glabrata.

Methods

We evaluated the usefulness of CaC in the identification of C. dubliniensis, C. famata, C. firmetaria, C. glabrata, C. guilliermondii, C. inconspicua, C. kefyr, C. lipolytica, C. lusitaniae, C. norvegensis, C. parapsilosis, and C. rugosa.

Results

Most NAC produced colonies that were shades of pink, lavender, or ivory. Several isolates of C. firmetaria and all C. inconspicua produced colonies difficult to differentiate from C. krusei. Most C. rugosa isolates produced unique colonies with morphology like C. krusei except in a light blue-green color. C. glabrata isolates produced small dark violet colonies that could be differentiated from the pink and lavender colors produced by other species. All seventeen isolates of C. dubliniensis produced green colonies similar to those produced by C. albicans.

Conclusion

C. glabrata and C. rugosa appear distinguishable from other species using CaC. Some NAC, including C. firmetaria and C. inconspicua, could be confused with C. krusei using this medium.     

Occurrence and the sensitivity to drugs of fungi other than Candida albicans isolated from the vagina

Frequency of occurrence of fungal species distinct from C. albicans isolated from vaginal mucosa and their sensitivity to antimycotic chemotherapeutics was determined. Material consisted of 452 fungal strains isolated from vagina from patients suffering from afflictions within genital area. Fungal strains isolated belonged to 13 genera. Fungi distinct from C. albicans constituted 27.1% of all the strains. Fungi the most frequently isolated from vagina belonged to following genera: T. glabrata 35.2% C. krusei 18.4% C. pseudotropicalis 15.2% S. cerevisiae 10.4%. In the majority of cases of vaginal infections caused by fungi distinct from C. albicans, Lactobacillus sp. was present and normal pH values of vaginal content 3/4 with variable number of leucocytes were observed. Evaluation of sensitivity to antimycotic drugs of fungal strains was performed by agar dilution technique. In this study the following chemotherapeutics were assayed: nystatin, pimaricin, amphotericin B, flucytosine, clotrimazole, miconazole and ketoconazole. It is worth to underline resistance of T. glabrata and S. cerevisiae to clotrimazole and ketoconazole. Moreover, resistance of strains belonging to genera C. krusei and C. pseudotropicalis to amphotericin B and C. krusei strains to nystatin and flucytosine was noted.     

Isavuconazole and Nine Comparator Antifungal Susceptibility Profiles for Common and Uncommon Candida Species Collected in 2012: Application of New CLSI Clinical Breakpoints and Epidemiological Cutoff Values

The in vitro activity of isavuconazole and nine antifungal comparator agents was assessed using reference broth microdilution methods against 1,421 common and uncommon species of Candida from a 2012 global survey. Isolates were identified using CHROMagar, biochemical methods and sequencing of ITS and/or 28S regions. Candida spp. were classified as either susceptible or resistant and as wild type (WT) or non-WT using CLSI clinical breakpoints or epidemiological cutoff values, respectively, for the antifungal agents. Isolates included 1,421 organisms from 21 different species of Candida. Among Candida spp., resistance to all 10 tested antifungal agents was low (0.0–7.9 %). The vast majority of each species of Candida, with the exception of Candida glabrata, Candida krusei, and Candida guilliermondii (modal MICs of 0.5 µg/ml), were inhibited by ≤0.12 µg/ml of isavuconazole (99.0 %; range 94.3 % [Candida tropicalis] to 100.0 % [Candida lusitaniae and Candida dubliniensis]). C. glabrata, C. krusei, and C. guilliermondii were largely inhibited by ≤1 µg/ml of isavuconazole (89.7, 96.9 and 92.8 %, respectively). Decreased susceptibility to isavuconazole was most prominent with C. glabrata where the modal MIC for isavuconazole was 0.5 µg/ml for those strains that were SDD to fluconazole or WT to voriconazole, and was 4 µg/ml for those that were either resistant or non-WT to fluconazole or voriconazole, respectively. In conclusion, these data document the activity of isavuconazole and generally the low resistance levels to the available antifungal agents in a large, contemporary (2012), global collection of molecularly characterized species of Candida.     

The taxonomy of the anascosporous yeast-like fungi

Conclusion The species of yeast-like anascosporogenous fungi most frequently isolated from man were found to be the following: albicans, tropicalis, pseudotropicalis, Krusei, parakrusei, stellatoidea and Guilliermondi. A restudy of old cultures maintained in culture bureaus for long periods of time has allowed investigators to add other species to this list. These old cultures, representing single isolations, were thought to be partially dissociated because both rough and smooth colonies developed on blood agar plates at 37°C. when streaked from Sabouraud's glucose broth. When the smooth colony was picked for study, the culture could be identified as one of the most frequently isolated species.The rough colonies, however, showed certain differences which allowed them to be classified as distinct species. To avoid characterizing new species on the basis of dissociative changes, freshly isolated cultures should be identified immediately by some rigidly standardized technique giving constant results.A single genus, to be used internationally, has been proposed for these fungi which were obviously too closely related to be separated generically. Since Syringospora Quinquaud 1868 was the first validly published genus, it can be replaced by a more recently published genus only by establishing the latter as a nomen conservandum with appropriate emendation and the selection of the proper type species.1. Presented at the Third International Congress for Microbiology, Sept. 2–9, 1939, New-York, New-York.Aided by a grant from the John and Mary R. Markle Foundation.     

Comparative observations of ultrastructure of five species of Candida

An electron microscopic comparison was made of five species ofCandida, namely:C. guilliermondii, C. krusei, C. parapsilosis, C. stellatoidea andC. tropicalis. The cell wall, plasma membrane and the cytoplasm with its organelles were described. The cell wall ofC. tropicalis was twice as thick as the cell wall in the other species.C. krusei appeared with distinct, rather elaborate wall sculpturing, a feature not pronounced in the other four species. A single nucleus with nucleolus appeared only in micrographs ofC. guilliermondii andC. krusei. At the same time, large central electron-luscent area (vacuole) appeared in the cells ofC. guilliermondii, C. parapsilosis andC. stellatoidea. The cytoplasm ofC. tropicalis was characterized by a granular appearance. Budding cells and pseudohyphae appeared similar to single cells in their general organelles. Such organelles in species studied were similar to these reported for other yeasts. These include: mitochondria, lipid granules, endoplasmic reticulum, ribosomes and vacuoles.Southwest Foundation for Research and Education, San Antonio, Texas.In partial fulfillment of the requirement of course work for Master of Science, Incarnate Word College, San Antonio.     

Xylitol production by Candida species grown on a grass hydrolysate

Xylitol was produced by selected species of the yeast Candida after growth on a medium containing a hydrolysate of the North American perennial prairie grass big bluestem. The grass was hydrolysed by a combination of dilute acid and enzymatic treatments. After growth on the medium for 120 h at 30 °C, Candida tropicalis ATCC 750 produced a 1.4-fold higher level of xylitol than did C. tropicalis ATCC 20215 while biomass production by C. tropicalis ATCC 750 was 1.7-fold higher than Candida guilliermondii ATCC 20216. The xylitol yields observed for C. tropicalis ATCC 750, Candida mogii ATCC 18364 and C. guilliermondii ATCC 20216 were at least 1.4-fold higher than the yield observed for C. tropicalis ATCC 20215 after growth for 120 h at 30 °C.     

Evaluation of the Pro-Lab ID ring system for the identification of medically important yeasts

We evaluated 151 coded isolates of medically important yeast species belonging to the genera Candida, Cryptococcus, Geotrichum, Rhodoturula, Saccharomyces and Torulopsis using the newly developed rapid Pro-Lab Identification Ring, PL 960 system (PLID-Ring). All isolates were concurrently identified by the API 20C and conventional procedures comprising macro- and micromorphology, assimilation and fermentation of various carbon and nitrogen compounds. The PLID-Ring system identified isolates of Candida albicans, C. kefyr, C. krusei, C. lusitaniae, C. parapsilosis, Rhodotorula rubra, and Torulopsis glabrata with 100% accuracy in 24 h. This system identified C guilliermondii and S. cerevisiae isolates with an accuracy of 90% and 86%, respectively, while those belonging to Cr. neoformans, T. candida (= C. famata), C. rugosa and C. tropicalis were identified with 38.4%, 50%, 12.5% and 50% accuracy, respectively. Three isolates of Cr. laurentii were not identified by the PLID-Ring system. The overall accuracy of the PLID-Ring system was 81.45% (123 of 151 isolates). However, the system does not include species such as Cr. laurentii in its data base. When these three Cr. laurentii isolates were excluded from the evaluation, the accuracy of the PLID-Ring system increased from 81.45% to 83.1%.