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Histoplasmosis is caused by Histoplasma capsulatum, a dimorphic fungus. Because histoplasmosis is usually a self-limited disease in the majority of cases, treatment often is not needed in the normal host. However, severe cases of acute pulmonary histoplasmosis require therapy. Amphotericin B is considered the treatment of choice.
Penicillium marneffei is a rare human pathogen that may infect either healthy or immunocompromised hosts. In methenamine silver-stained preparations of bronchoalveolar lavage fluid from a patient with dermatomyositis on steroid treatment, round-to-oval intracellular and extracellular microorganisms were found. The finding of occasional septate and elongated forms established the microorganism as probably P marneffei, which was confirmed on culture. Distinguishing this rare fungus from Pneumocystis carinii is important because these two diseases require different forms of treatment.
3-(3-Bromo-4-methoxyphenyl)-4-amino-5-mercapto-1,2,4-triazole was prepared starting from p-anisic acid. This new triazole was employed in the synthesis of some N-bridged heterocycles. All the newly synthesized compounds were characterized by analytical, IR, 1H-NMR and Mass Spectral studies. Some of the newly synthesized compounds were screened for their antifungal property against Thielaviopsis paradoxa, a fungus which is reported to cause stem-bleeding disease in coconut plants.
In the present paper we will present a general view of the main mycoses affecting domestic animals. In the dog, we show the importance of the dermatophytoses, increased by its zoonosic character and the problem of the false negatives in the traditional microbiological culture. Under the general term of systemic mycoses we include a series of conditions considered usually as aspergillosis, bat with more and more fungal species implicated as possible etiological agents. In addition, fungi, especially yeasts, are being implicated in canine otitis; in our laboratory 86 % of canine chronic otitis involve a yeast etiology, alone or in collaboration with bacteria. In the cat, dermatophytes are more common than in the dog, and are the main source of infection in man, with the description of a high percentage of healthy carrier animals. Cryptococcosis is a severe disease, usually secondary to other process, especially feline immunodeficiency. In cows we refer to fungal abortion, with three main fungi implicated: Aspergillus, Candida and Zygomycetes. In some areas of our country the percentage of fungal abortion is around 10 %. A consequence of the multiple use of antibiotics in mastitis is selection of yeasts, especially those included in the genera Candida and Cryptococcus. Bovine dermatophytoses is an extensively disseminated disease in our country, with a commercial specific vaccine available. In small ruminants, Cryptococcus causes severe pneumonic processes that could be confused clinically with other conditions. An additional important question is the description of isolation of this fungus from tree leaves. In poultry, aspergillosis is a known and controlled disease, but with more importance in captive wild birds with an ecological value. In horses, we emphasize the lung infections by different fungi, specially Pneumocystis carinii, and arthritis by yeasts as consequence of wound contamination or surgery.
Activation of virulence in pathogenic fungi often involves differentiation processes that need the reset of the cell cycle and induction of a new morphogenetic program. Therefore, the fungal capability to modify its cell cycle constitutes an important determinant in carrying out a successful infection. The dimorphic fungus Ustilago maydis is the causative agent of corn smut disease and has lately become a highly attractive model in addressing fundamental questions about development in pathogenic fungi. The different morphological and genetic changes of U. maydis cells during the pathogenic process advocate an accurate control of the cell cycle in these transitions. This is why this model pathogen deserves attention as a powerful tool in analyzing the relationships between cell cycle, morphogenesis, and pathogenicity. The aim of this review is to summarize recent advances in the unveiling of cell cycle regulation in U. maydis. We also discuss the connection between cell cycle and virulence and how cell cycle control is an important downstream target in the fungus-plant interaction.
A case of phycomycosis (Mucor) complicating urologic surgery is presented. It is a rare disease that is rapidly fatal, though caused by a usually benign saphophytic fungus. No previous urologic surgical cases have been found in the literature where Mucor has been a postoperative complication.
Sociality can be associated with significant costs due to the increased risk of disease transmission. However, in some organisms the costs may be offset by benefits due to improvements in defences against parasites. To examine this possible trade-off between infection risk and disease resistance, we used Acromyrmex leaf-cutting ants and the entomopathogenic fungus Metarhizium anisopliae as the model system. Ants exposed to the parasite were found to have substantially improved survival when they were kept with nest-mates, while the cost of being in a group in terms of increased disease transmission was very low. The efficiency of transmission is described by the transmission parameter, which decreased with increasing host density showing that transmission rates are inversely density dependent. Both grooming and antibiotic secretions appeared to be important in resistance against the parasite, with the defences of small workers being particularly effective. The results indicate that leaf-cutting ant colonies may have much greater resistance to disease than would be predicted from the high densities of host individuals within them. Unlike most organisms, group living in these ants may actually be associated with a net benefit in terms of disease dynamics.
A new fungal pathogen of Tipula paludosa (Tipulidae: Diptera) larvae, Conidiobolus osmodes (Ancylistaceae: Entomophthorales), was found during a survey of tipulid larval pathogens in Northumbria and Cumbria in England in 1997-1999. The fungus caused an epizootic in a population at Close House during autumn 1999 and spring 2000 with prevalence rising fourfold reaching about 40% in April 2000. The disease development was presented and the fungus was described from naturally infected larvae and artificial cultures.
We describe a neonate with congenital heart disease in whom a sternal wound infection caused by the filamentous fungus Curvularia lunata developed following cardiac surgery. Despite their widespread distribution in the environment, Curvularia species rarely cause human infection. We also review the 43 cases of curvularia infection previously reported in the English-language literature; only four of these cases occurred in children. A wide spectrum of infections--including keratitis, cutaneous infections, sinusitis, allergic bronchopulmonary disease, pneumonia, chronic ambulatory peritoneal dialysis-related infections, endocarditis and disseminated infections--have been described. Curvularia is a pathogen that can cause disease in both immunocompetent and immunocompromised hosts, although more severe and disseminated disease occurs in patients with defective immune function. Surgery alone usually is successful for treating locally invasive disease, although a combination of medical and surgical therapy is necessary for treating disseminated infections.
CASE HISTORY: This report describes an outbreak of high mortality of heifers after they consumed harvested maize fields parasitised with the fungus Diplodia maydis. CLINICAL FINDINGS: Clinical signs observed were generalised muscle tremors, incoordination, ataxic hindquarters, paralysis and death. The morbidity of the outbreak was 27/500 (5.4 %) and mortality 10/27 (37%). No gross lesions were observed, however histopathological examination revealed moderate to severe degeneration of myelin shafts in the white matter of the cerebellum. Diplodia maydis infection of maize was identified from visual characteristics of mycelia and pycnidia. DIAGNOSIS: Diplodia toxicity (diplodiosis). CLINICAL RELEVANCE: This is the first description of the poisoning of cattle by maize contaminated with D. maydis in Argentina, where feeding cattle on harvested maize fields is common practice. It is possible this disease could occur in other countries, like New Zealand, where this fungus is known to be present.
Many fungal pathogens undergo morphological transformations during host invasion. However, the significance of this for fungal pathogenesis is not clear. Both yeast and hyphal cells have properties well suited to tissue invasion and evasion of the immune system. However, molecular control circuits that regulate morphogenesis also regulate the expression of other virulence traits. To establish the extent to which morphogenesis impacts on pathogenesis, it is necessary to characterise the morphology of the fungus at different stages and locations during the natural history of a disease and to untangle how gene expression is modulated at these stages. This review considers the role of morphogenesis in fungal infection and argues that no simple, universal relationship can be drawn between morphology and the invasive potential of a fungus.
Eighty-five cases of tinea capitis due to T. tonsurans were observed in the San Francisco Bay area during the five years 1950-54. This disease, unlike the common microsporum infections, sometimes affects adults and adolescents. Hairs infected with T. tonsurans do not fluoresce under the Wood's light. Diagnosis is a laboratory procedure in which the fungus is isolated from the hair. There are three clinical varieties of the disease. The course is prolonged and treatment is unsatisfactory. The disease apparently has spread from Mexico, through the Southwest and Southern California. Control is difficult.
We describe a murine model of acute blastomycosis pneumonia induced by Blastomyces dermatitidis conidia. Anesthetized mice were infected by placing a droplet containing conidia suspended in sterile saline on the nares and allowing the suspension to be aspirated into the lungs. Conidia were obtained from mycelia derived from the yeast forms of two well characterized strains of B. dermatitidis, ATCC 26199 and 26197. ATCC 26199 yeast and conidia were highly virulent in BALB/cByJ mice whereas both forms of ATCC 26197 were incapable of causing disease in 60 days. Conidia and yeasts of the virulent strain caused pathologic changes primarily in the lungs, whereas no abnormalities were seen in the lungs, or elsewhere, in mice infected with the a virulent strain. Small numbers of ATCC 26199 yeast forms were found in scattered foci in liver and kidneys, but no inflammatory reaction surrounded the fungus. This murine model of acute blastomycosis pneumonia mimics the acute disease in humans and is initiated with the naturally infectious particle.
Paracoccidioides brasiliensis is the causative agent of paracoccidioidomycosis, a disease that affects 10 million individuals in Latin America. This report depicts the results of the analysis of 6,022 assembled groups from mycelium and yeast phase expressed sequence tags, covering about 80% of the estimated genome of this dimorphic, thermo-regulated fungus. The data provide a comprehensive view of the fungal metabolism, including overexpressed transcripts, stage-specific genes, and also those that are up- or down-regulated as assessed by in silico electronic subtraction and cDNA microarrays. Also, a significant differential expression pattern in mycelium and yeast cells was detected, which was confirmed by Northern blot analysis, providing insights into differential metabolic adaptations. The overall transcriptome analysis provided information about sequences related to the cell cycle, stress response, drug resistance, and signal transduction pathways of the pathogen. Novel P. brasiliensis genes have been identified, probably corresponding to proteins that should be addressed as virulence factor candidates and potential new drug targets.
Thirty six cases of acute disseminated paracoccidioidomycosis in 3 to 12 year-old children, natives of the state of Rio de Janeiro, were seen in the period 1981-1996. All patients were residents in the rural region of 15 counties, scattered on the Southwestern part of this state. The rural region of two neighboring counties, where 16 cases (44.4%) occurred, was visited. It exhibited the environmental conditions that are considered favorable to the survival of P. brasiliensis. The most important of these conditions, abundant watercourses and autochthonous forest, are distributed on well defined and limited areas, in which the dwellings are also localized. Probably, a careful epidemiological study of forthcoming cases of the disease in children may facilitate the search for the micro-niche of the fungus.
The production of acetylenic phenol metabolites in vitro by three strains of the ascomycete Eutypa lata, the causative agent of dying-arm disease in grapevines, has been investigated. Metabolite composition and yields differed significantly between strains and with growth medium but usually reached a maximum after 24-30 days of fungal growth. A general method for the analysis and identification of metabolites by gas chromatography/mass spectrometry of their trimethylsilyl ether derivatives was developed and individual compounds were quantitated by analytical high-performance liquid chromatography (HPLC) and separated by preparative HPLC. The phenolic aldehyde, eutypine (1), reported to be the grape phytotoxin, occurred in only one of the strains examined whereas the primary metabolite was the corresponding alcohol, eutypinol (2), the presumptive detoxification product. A novel metabolite was isolated as a major constituent, together with a minor component, and their structures were established by spectroscopic methods as a methoxyquinol, named eulatinol (4), and a chromene analog (9) of 2, respectively. The evidence suggests that 1 is not solely responsible for phytotoxicity in grapevines but that dying-arm disease may result from a suite of compounds elaborated by the fungus, with the composition dependent on fungal strain and nutritional source.
Fluconazole, a triazole antifungal agent newly developed by Pfizer Inc.. was given orally to 4 patients with deep mycosis. Fluconazole was markedly effective against septicemia due to Candida and oral candidiasis accompanied with lingual ulcer in spite of seriousness of these underlying disease. In 2 patients with aspergilloma, eradication or contraction of fungus ball was observed and the drug was judged to be effective. In vitro MICs of fluconazole against clinically isolated Aspergillus spp. were much higher than its serum levels leaving a large discrepancy between in vitro activity and clinical efficacy. Although the dosage was 100-300 mg daily for 8 days to 6 months, neither adverse reactions nor laboratory parameter abnormalities were observed. The above results suggest that fluconazole is a useful agent in the treatment of fungal infections.
The susceptibility of the domestic pig to intoxication by the causative mycotoxin of lupinosis was established experimentally. The symptomatology and pathology of the disease produced by the administration of toxic cultures of the fungus, Phomopsis leptostromiformis (Kühn) Bubák ex Lind to pigs are described. The toxin induced severe loss of weight and, in many cases, posterior paresis or paralysis. The principal gross lesions were generalised icterus, orange-red discoloration of the liver, nephrosis and, in some, enterorrhagia. Microscopically there was severe necrosis of hepatocytes and kidney tubular epithelium as well as myocardial degeneration. In the more chronic cases hepatocytes became anaplastic and arranged in acini. The production of toxin by P. leptostromiformis on yellow maize is reported and a method for production of toxic material is described.