Showing papers in "Mycopathologia in 1984"

A characterization of pH-regulated dimorphism in Candida albicans

Abstract: When cells of the dimorphic yeast Candida albicans are grown to stationary phase in defined liquid medium at 25°C, they accumulate as singlets in Gl of the cell cycle. When these pluripotent, stationary phase singlets are released into fresh medium at 37°C, they synchronously evaginate after an average period of 135 to 140 minutes and form either buds or mycelia, depending upon the pH of the medium into which they are released. This method of dimorphic regulation offers the distinct advantage of comparability and serves as a very precise method for temporal comparisons of molecular and cytological events related to the establishment of the alternate growth phenotypes. In the present report, we have carefully examined the effects of individually varying pH or temperature on the length of the pre-evagination period, the population synchrony for evagination, and the phenotype of daughter cells. Exact phenotypic transition points, optima, and upper limits are defined for both temperature and pH. In addition, a method of pH-regulated dimorphism is developed in which the original temperature shift is removed from the inductive process. Finally, a common transition phenotype is described for cells reverting from the initial mycelial to budding phenotype when either pH or temperature traverse their respective transition points. The advantages as well as limitations of pH-regulated dimorphism are discussed in detail.

The relationship of Aspergillus flavus and Aspergillus parasiticus with reference to production of aflatoxins and cyclopiazonic acid

Abstract: Forty-seven isolates of Aspergillus parasiticus were analyzed for production of aflatoxins B1, B2, G1, G2, and cyclopiazonic acid. None produced cyclopiazonic acid, whereas 46 of 47 produced aflatoxins B1 and G1. These data are related to previous studies pertaining to A. flavus and illustrate species validity from a biochemical standpoint.

A survey of dermatophytes isolated from human patients in the United States from 1979 to 1981 with chronological listings of worldwide incidence of five dermatophytes often isolated in the United States.

Abstract: A survey of dermatophytes isolated from patients seeking medical advice was made from 1979 to 1981 in the United States. The survey included 54 locations with data from 40 cities and 2 states. Correlations of these data with that of the other localities of the world were made to illustrate the dynamic epidemiology of several common dermatophytes. The most often isolated dermatophyte in this survey was Trichophyton rubrum having 53.66% of the total for these three calendar years. In a chronological listing of ringworm infections caused by this organism, many areas of the world have reported similar increased incidence of this pathogen. Trichophyton tonsurans was isolated 27.85% of the total. A dramatic increase of this pathogen as a cause of tinea capitis has been observed in most cities of the United States. It has been isolated in 25 different countries of the world. The percentage of isolation of Trichophyton mentagrophytes was 8.56%. This percentage may not be near the true incidence of infection by this dermatophyte because the infections are mild and respond to treatment without the individual seeking medical advice. Since the 1950s the percentage of isolations of the total has dropped for T. mentagrophytes in the United States. Epidermophyton floccosum accounted for 4.36% of the total. In a few areas of the world it causes over 30% of the total of dermatophytoses. Microsporum canis was isolated 3.72% of the total in the United States. It has recently been reported to be the dominant agent of tinea capitis in several South American countries, Tucson, Arizona and Kuwait. Once the dominant pathogen of tinea capitis in children in the United States, it was replaced by Microsporum audouinii before 1960. Today in the United States, M. audouinii only accounts for 0.30% of the total. It is considered eliminated as a pathogen in England. In this survey, isolated less than 1.0% of the total were Microsporum gypseum, Microsporum ferrugineum, Microsporum nanum, Microsporum fulvum and Trichophyton schoenleinii. Trichophyton meginii and Trichophyton terrestre were reported isolated but no numerical data were available.

Strain differentiation of pathogenic yeasts by the killer system

Abstract: High sensitivity rates to the activity of killer toxins produced by 25 species of yeasts belonging to the genera Candida, Hansenula, Pichia, Rhodotorula, Saccharomyces and Trichosporon have been observed among 112 yeast isolates (25 Cryptococcus neoformans, 29 C. glabrata, 16 C. parapsilosis, 20 C. pseudotropicalis and 22 C. tropicalis). The highest sensitivity has been observed among the C. parapsilosis isolates, the lowest in C. glabrata strains. Genera Pichia and Hansenula proved to have the greatest killer activity. A killer system, formerly used for differentiating C. albicans isolates within the species, proved to be valid as epidemiological marker when applied to 112 strains of pathogenic yeasts.

Effect of geocarposphere temperature on pre-harvest colonization of drought-stressed peanuts by Aspergillus flavus and subsequent aflatoxin contamination

Abstract: Florunner peanuts grown in research plots were subjected to 5 soil temperature and moisture treatment regimes resulting in A. flavus infestation and subsequent aflatoxin contamination in drought-stressed peanuts. Treatments imposed beginning 85 days after planting were drought, drought with heated soil and 3 drought treatments with cooled soil. The incidence of A. flavus in drought-stressed, unshelled, sound mature kernels (SMK) decreased with decreases in the mean 5 cm deep soil temperature. The incidence of A. flavus was greater in inedible categories and in damaged kernels than in SMK. The mean, threshold, geocarposphere temperature required for aflatoxin development during the latter part of the peanut growth cycle was found to be between 25.7° C and 27° C.

Recent studies on aspergillosis in turkey poults

Abstract: A review of the studies on aspergillosis in turkey poults at the National Animal Disease Center include limited field studies, pathogenicity studies, and vaccine development. Natural ventilation in turkey rearing houses was effective in reducing airborne propagules of four major fungal genera, but the effectiveness of ventilation appeared to be limited by the width of the building. Aspergillus fumigatus was more effective than A. flavus in producing mortalities in aerosol exposed poults. Toxigenicity of A. flavus did not enhance its pathogenicity, and no apparent aflatoxin production occurred during pathogenesis in infected turkey poults. Spores of A. fumigatus were disseminated quite rapidly in poults exposed to aerosols, and alveolar macrophages from respiratory lavages taken immediately after exposure contained spores of A. fumigatus. Vaccines produced from germlings of A. fumigatus and administered to turkey poults were the most efficacious of five vaccines tested against challenge exposure to aerosols of A. fumigatus spores.

Enzyme-linked immunosorbent assay (ELISA) in the paracoccidioidomycosis

Abstract: An enzyme-linked immunosorbent assay (ELISA) for detection and quantification of antibodies antiParacoccidioides brasiliensis is described. Polystyrene plates have been used as solid phase to absorb P. brasiliensis metabolic yeast phase antigen. Twenty sera of proven paracoccidioidomycosis, 11 of histoplasmosis due Histoplasma capsulatum, 20 of aspergillosis and 20 human normal sera were tested. Ninety-five percent of the paracoccidioidomycosis sera had O.D. superior to 0.150 (from 0.163 to 2.650) at 1/400 serum dilution. ELISA assay was compared with counterimmunoelectrophoresis and erythro-immunoassay tests; a correlation was observed only with erythro-immunoassay. ELISA test should give new perspectives for the serodiagnosis of paracoccidioidomycosis.

Effect of soil temperature and drought on peanut pod and stem temperatures relative to Aspergillus flavus invasion and aflatoxin contamination

Abstract: Peanut stem and pod temperatures of plants growing in irrigated, drought, drought-heated soil, and drought-cooled soil treatments were determined near the end of the growing season. Mean soil temperatures of the treatments during this period were 21.5°, 25.5°, 30° and 20 °C, respectively. Peanut stem temperatures in all drought treatments reached a maximum of ca. 40 °C and for 6–7 h each day were as much as 10 °C warmer than irrigated peanut stems. Pod temperatures in drought-heated soil and drought treatments were ca. 34 °C and 30 °C, respectively, for several hours each day. As pod temperatures approached the optimum for A. flavus growth (ca. 35 °C), the proportion of kernels colonized and aflatoxin concentrations increased. Increased plant temperature without accompanying pod temperature increases (drought-cooled soil) resulted in colonization percentages and aflatoxin concentrations only slightly higher than those of the irrigated peanuts.

The distribution of nematophagous fungi in the maritime Antarctic

Abstract: Endoparasitic and predatory nematophagous fungi are widely distributed throughout the maritime Antarctic, being recorded along the Antarctic Peninsula as far south as 68° S. Fungi were recorded from 71% of the sites examined with Cephalosporium balanoides and Dactylaria gracilis being the commonest recorded endoparasite and predator, respectively. Endoparasites with adhesive and nematode-attracting conidia were shown to be more abundant and to have a competitive advantage in the Antarctic ecosystem over those parasites requiring their conidia to be ingested before infection could occur. Predators able to form traps spontaneously on germination were shown to be far more abundant than those species with a more saprophytic mode of existence, with constricting rings being the most commonly isolated trapping mechanism. Species capturing nematodes by three-dimensional networks were restricted to bird-associated sites indicating that they are able to grow saprophytically in such organically enriched material. Nematophagous basidiomycetes and phycomycetes were absent except for a single Myzocytium sp. isolated from heated soil.

Application of immunoprecipitation techniques to the diagnosis of cutaneous and extracutaneous forms of sporotrichosis.

Abstract: Sporotrichosis is a mycosis which in our country has been described as only producing cutaneous and subcutaneous infections; in other countries it has been reported as causing pulmonary, bone, joint and meningeal infections. Possibly the systemic form also occurs in Venezuela since, along with the causative agent, all other factors considered as predisposing to systemic infection exist here. Through immunodiffusion (ID) and immunoelectrophoresis (IEP) and using a filamentous form metabolic antigen from Sporothrix schenckii, we were able to demonstrate precipitating antibodies against this fungus both in patients with cutaneous sporotrichosis, diagnosed by culture of the infecting agent, and in patients with pulmonary lesions. The IEP test showed the presence of an anodic arc which we have called the 'S' arc, which could be one of the specific antigens of S. schenckii.

Survey of airborne fungus spores at Taif, Saudi Arabia.

Abstract: Fifty-eight species and one variety belonging to 25 genera were collected from the atmosphere of Taif from August 1981 to July 1982 (12 exposures for each type of media) on glucose- and cellulose-Czapek's agar plates at 28 °C.

Fungi from otitis media of agricultural field workers.

Abstract: Twenty four fungi were isolated from ear wax or otitis media of agricultural field workers, of which 18 are being reported for the first time from India. Direct observation, revealed the presence of hyphal fragments, spores of Alternaria, Bipolaris, conidial head of Aspergillus, smut teliospores and pollen. Spores of only four fungi, Alternaria humicola, Aspergillus niveus, Bipolaris spicifera and Fusarium moniliforme germinated in otitis media at 37 ° C, and their germination was affected by relative humidity. Alternaria humicola and Aspergillus niveus appeared to be the causative agents of otomycosis, and otitis media is fungistatic in nature.

Kerantinophilic fungi isolated from a small pool

Abstract: The keratinophilic fungi occurring in the water of a small pool were examined by membrane filtration with monthly sampling throughout a year. Chrysosporium evolceanui, C. keratinophilum, C. tropicum, Trichophyton terrestre and Microsporum gypseum were the most frequently found species. The results of this survey are discussed.

Propriétés antibactériennes et génotoxiques de 33 mycotoxines

Abstract: Most of the 33 fungal metabolites tested provoke: Bacterial growth inhibition of Bacillus thuringiensis similar to lethal effect of antibiotics. Positive response in the 'Rec' assay using strains of Bacillus subtilis; this fact shows that these toxins are DNA modifying agents. Enlargement of cell volume in the first bacteria species; this cell-abnormality induction resembles those obtained with mitomycin C. Correlation between elongation of cells (filamentation) and in vivo carcinogenicity of mycotoxins is discussed. The filamentation should be an expression of a perturbated DNA replication (S.O.S.-error prone repair) as the consequence of DNA damages induced by genotoxic agents (i.e. carcinogens).

Fate of aflatoxin B-1 in fermented dairy products.

Abstract: Polyacrylamide gel electropheresis and thin layer chromatography (TLC) were applied to detect the fate of aflatoxin B-1 in milk fermented with an active culture of Streptococcus lactis (ATCC-11454). TLC analysis revealed the formation of two fluorescent metabolites (B2a and R0) in fermented milk. Electropheretic analysis of both casein and whey protein showed fluorescent bands in the region of Kappa-casien and immunoglobulin which are glycoproteins in nature. The transformation of B-1 to the nontoxic metabolite B2a and the less toxic compound aflatoxicol (R0) reflects the preference for fermented dairy products in consumption in order to reduce chances of toxicity.

Keratinophilic fungi from urban soils of Barcelona, Spain

Abstract: Fifty soil samples of urban soils of Barcelona (Spain) were analyzed. We isolated the following keratinophilic fungi: Trichophyton ajelloi, Microsporum gypseum, Chrysosporium keratinophilum, C. evolceanui, C. tropicum, C. indicum and C. asperatum.

Non-specific immunosuppression by Cryptococcus neoformans infection

Abstract: Cryptococcus neoformans-infected animals were found to be immunosuppressed when tested by a variety of assays for immune competence. Primary humoral immune responses and delayed-type hypersensitivity reactions to sheep erythrocytes were suppressed in animals which had been infected for two weeks. Lymphocyte proliferation (LP) assays to sRBC stroma were also significantly diminished at two weeks of infection. Spleen cells of infected mice suppressed the LP response of sRBC immunized, normal mice in vitro. At least a part of the suppression could be attributed to a nylon wool non-adherent cell. Suppressor cells continued to be present in spleen cell suspensions following treatment with anti-T cell serum or anti-immunoglobulin and complement. When infected spleen cells were separated by adherence to plastic, both the adherent and non-adherent fractions exhibited suppressive activity. Incubation of infected spleen cells in tissue culture for 48 hr resulted in the elaboration of soluble immunosuppreessive factors into the tissue culture medium. These data indicated that immune suppression in cryptococcosis can occur as a result of infection with Cryptococcus neoformans, and that at least one mechanism involved is the induction of adherent and non-adherent suppressor cells in the spleens of infected mice.

Mycoflora of bean, broad bean, lentil, lupine and pea seeds in Saudi Arabia

Abstract: Using the seed-plate method on glucose-Czapek's agar at 28 °C (±2 °C), 24 genera and 60 species in addition to two varieties were collected from bean, broad bean, lentil, lupine and pea seeds. The most frequent genera were Aspergillus (16 species + two varieties), Penicillium (14 species), Rhizopus (1 species) and Yeasts, followed by Fusarium (3 species), Mucor (4 species) and Drechslera (3 species). From the preceding genera, Aspergillus niger, A.flavus, Penicillium citrinum, Rhizopus stolonifer, Fusarium moniliforme or F. oxysporum, Mucor hiemalis or M. racemosus and Drechslera spicifera were the most prevalent species.

A reliable fluorescent stain for fungi in tissue sections and clinical specimens

Abstract: A simple and reliable staining technique is described using the fluorescent brightener Blankophor BA which binds specifically to fungal cell wall components. Potential diagnostic applications are shown.

Dermatophytes isolated from laboratory animals.

Abstract: In order to determine the presence of dermatophytes in healthy skin, 200 animals from the animal house of Faculty of Medicine, U.N.A.M., were studied; these were 50 rats, 50 rabbits, 50 mice, and 50 guinea pigs. Out of these 200 animals, 29.5% had positive isolation of Trichophyton mentagrophytes, var. lacticolor. The frequency variation was: rats, 68%; rabbits, 36%; mice, 8%; and guinea pigs, 6%. Male rats and male rabbits, had the higher incidence of positives. The epidemiologic repercussion of these and the significance to use these animals in biomedical investigation is discussed.

Production of oxalic acid by Penicillium oxalicum in culture and in infected yam tissue and interaction with macerating enzyme

Abstract: Penicillium oxalicum produced the greatest amount of oxalic acid in liquid culture and in infected yam tissue within 2 days of inoculation, whereas production of cell wall-degrading enzymes reached a peak eight days after inoculation. Coupled with the production of oxalic acid was the lowering of the culture pH and of infected yam tissue. Oxalic acid was not produced simultaneously with endo-polygalacturonase (the macerating enzyme), but it acted synergistically with the enzyme by sequestering calcium present in the middle lamella of yam cells and conditioning the cell wall for hydrolysis.

Dermatophytes in Portugal (1972–1981)

Abstract: For the years 1972–1981, 7 333 isolates of dermatophytes belonging to 14 species were obtained from glabrous skin (32%), feet (28%), groin (19%), scalp (8%), toenails (7%), fingernails (3%) and beard (1%)., T. rubrum represented 50% of all the isolates and was the most frequent species on glabrous skin, groin and nails. T. mentagrophytes (24%) was mainly obtained from the feet, E. floccosum (9%) from the groin and T. megninii (4%) from uncovered areas of the skin, fingernail and beard. These 4 species predominated in men. M. canis was the commonest agent on the scalp and in children up to 11 years.

Survey on the mycoflora of Egyptian wheat grains and their lemmae and paleae.

Abstract: The plating technique has been used to study the fungus floras of covered and uncovered wheat grains and their lemmae and paleae on glucose-cellulose and 40% sucrose-Czapek's agar at 28° C. Seventy-two species and 28 genera were collected from the three microhabitats on the three types of media. On glucose-Czapek's agar the most frequent species were Aspergillus niger, A. flavus, A. terreus, A. nidulans, Alternaria alternata, Cladosporium herbarum and Fusarium Oxysporum. On cellulose and 40% sucrose-Czapek's agar, the composition of fungal floras of the three substrates and the frequency of prevalence of the individual fungi were basically similar to those obtained on glucose agar, but the frequency of some species was promoted or decreased.

Lack of carcinogenicity of agaritine by subcutaneous administration in mice

Abstract: Agaritine (A), an ingredient of the cultivated mushroom of commerce Agaricus bisporus, was administered by subcutaneous injection to two groups of randomly bred Swiss mice. In the first group the animals of both sexes were treated at a 100 μg/g body weight basis five times at weekly intervals, while in the second group the mice received a single A treatment of 100 μg/g body weight for females and 50 μg/g body weight for males. The administration of the compound resulted in no detectable carcinogenic effect in the animals. Since some of the breakdown products of A were shown to be carcinogenic in mice and the mushroom itself was found to be mutagenic, the field is discussed in the light of the obtained results.

Antifungal drug susceptibility testing. A critical review.

Abstract: The advent of new antifungal drugs provides clinicians with therapeutic options, and it is anticipated requests for fungal susceptibility testing in vitro will increase. Our own laboratory's experience indicates that results can be provided promptly even to distant medical centers. The need in this setting is standardization of procedures, so correlations with in vivo outcome can be made with in vitro results. The variables affecting current testing methods are reviewed. Newer methods of testing are summarized, including our experiences using a spectrophotometer as a tool to assay inhibition. Our understanding of the mechanisms underlying the results with this and classical methods are presented. Several methods were applied to a population survey of Candida albicans isolates, using the drug flucytosine as an example. The results were correlated with in vivo outcome in a mouse model of systemic candidosis. The in vitro results, in general, predicted survival, but exceptions occurred, and it appears the in vitro results provide a relative but not absolute indication of outcome.

Ecology of nematophagous fungi: Methods of collection, isolation and maintenance of predatory and endoparasitic fungi

Abstract: The methods employed in a recent investigation into the ecology of nematophagous fungi are examined in detail. The best sources from which fungi can be isolated are examined, and the main field collection and recovery techniques are compared and discussed. Other practical problems considered are the examination of plates, microscopy, identification, isolation and culture methods, maintenance of fungi, the production of nematodes as bait. A summary of the experimental techniques used is given.

Pathogenicity of Phomopsis ganjae on Cannabis sativa and the fungistatic effect of cannabinoids produced by the host

Abstract: The chronology of Phomopsis ganjae conidia germination and infection of Cannabis sativa leaves was observed with the scanning electron microscope. A-conidia germination approached 100% after 24 h, appresoria initiation began after 36 h; B-conidia germinated by 52 h but were not infective. Four-week-old C. sativa seedlings were more susceptible than 16-week-old plants, males more than females. THC and CBD, extracted and separated via TLC, inhibited P. ganjae conidia germination and hyphal growth.

Composition of the fungal flora of four cereal grains in Saudi Arabia.

Abstract: Using the grain-plate method and on glucose-Czapek's agar at 28°C, fifty-eight species belonging to 26 genera were collected from barley (42 species and 19 genera), maize (29 species and 16 genera), sorghum (32 species and 17 genera) and wheat grains (42 species and 18 genera).

Three new filamentous, fermenting Candida isolated from decayed wood in the evergreen rainy Valdivian forest of southern Chile

Abstract: Five novel representatives of the yeast genus Candida isolated from advanced stages of wood degradation from fallen trunks of Eucryphia cordifolia Cav., Laurelia sempervirens Weim., Laurelia philippiana Weim., Nothofagus dombeyii (Mirb.) Blume, and Nothofagus obliqua (Mirb.) Blume, in the evergreen rainy Valdivian forest of southern Chile, are described and illustrated. They clearly differ from all accepted Candida species to warrant their establishment as five new species of yeasts: Candida coipomensis sp. nov., Candida ralunensis sp. nov., Candida laureliae sp. nov., Candida osornensis sp. nov., and Candida llanquihuensis sp. nov.

Pathogenicity of the basidiospores of Filobasidiella neoformans.

Abstract: The pathogenicity of the purified basidiospores of Filosbasidiella neoformans was determined. The basidiospores were purified by successive filtration and inoculated into white Swiss female mice via the intracranial and intravenous route. At autopsy, infection was seen with as few as fifty inoculated cells. The brain, liver and spleen were examined culturally and histologically to prove the pathogenicity of the purified basidiospores.