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At least 919 records · Page 51Linked to original sources
PubMed2001

Comparison of the BACTEC MYCO/F Lytic bottle to the isolator tube, BACTEC Plus Aerobic F/bottle, and BACTEC Anaerobic Lytic/10 bottle and comparison of the BACTEC Plus Aerobic F/bottle to the Isolator tube for recovery of bacteria, mycobacteria, and fungi from blood.

The BACTEC MYCO/F Lytic blood culture bottle (Becton Dickinson Diagnostic Instrument Systems, Sparks, Md.) is designed to optimize the recovery of fungi and mycobacteria; however, this bottle also supports the growth of most aerobic bacteria. We compared the MYCO/F Lytic bottle with two other BACTEC bottles and the Isolator system for the recovery of bacteria as well as fungi and mycobacteria from blood. A total of 6,108 blood culture sets were inoculated with blood obtained from adult patients. Twenty-five to 28 ml of blood collected by a phlebotomy team for each blood culture set was randomly distributed into each of four blood culture receptacles: the Isolator tube (Wampole Laboratories, Cranbury, N.J.) and three BACTEC bottles: the MYCO/F Lytic bottle, the BACTEC Plus Aerobic/F bottle, and the BACTEC Anaerobic Lytic/10 bottle. The sediment from the Isolator tube was inoculated onto chocolate agar (CA), brain heart infusion agar (BHI), and Sabouraud dextrose agar (SDA) and into a BACTEC 13A bottle. Incubation durations were as follows: MYCO/F Lytic bottle, 42 days; Plus Aerobic/F bottle, 5 days; Anaerobic Lytic/10 bottle, 5 days; sediment from Isolator tube on CA, 3 days; sediment from Isolator tube on BHI, 30 days; sediment from Isolator tube on SDA, 30 days; and sediment from Isolator tube in a BACTEC 13A bottle, 42 days. Two isolates of Histoplasma capsulatum were recovered from the Isolator tube only. Three isolates of Mycobacterium tuberculosis complex were recovered: two isolates from the MYCO/F Lytic bottle only and one isolate from the Isolator tube (whose sediment was inoculated into the BACTEC 13A bottle) only. Two isolates of Cryptococcus neoformans were recovered: one from the MYCO/F Lytic bottle only and the other from the MYCO/F Lytic bottle and the Isolator tube (whose sediment was inoculated into the BACTEC 13A bottle). For potential pathogens overall, there was a statistical difference in recovery that favored the Isolator system over the MYCO/F Lytic bottle (P = 0.0015), including statistically significant differences for Staphylococcus aureus (P = 0.0001) and Streptococcus pneumoniae (P = 0.0313). However, there was no statistically significant difference between the two blood culture systems when detection of bloodstream infection was considered. The time to detection for all potential pathogens combined was less for the MYCO/F Lytic bottle than for the Isolator system (P = 0.0004). Overall, the potential pathogen recovery was greater for the BACTEC Plus Aerobic/F bottle than for either the Isolator system (P = 0.0003) or the MYCO/F Lytic bottle (P = 0.0001). However, the BACTEC Plus Aerobic/F bottle did not recover M. tuberculosis, H. capsulatum, or C. neoformans isolates. The combination of the Isolator system and MYCO/F Lytic bottle may be useful as a selective blood culture method to optimize the recovery of fungi and mycobacteria from blood. Compared with the manual Isolator system, the MYCO/F Lytic system has the advantage of less preanalytic processing and continuous automated monitoring of bottles for growth by the BACTEC 9240 instrument.

Adult↗
PubMed2001

In vitro fungicidal activities of voriconazole, itraconazole, and amphotericin B against opportunistic moniliaceous and dematiaceous fungi.

The NCCLS proposed standard M38-P describes standard parameters for testing the fungistatic antifungal activities (MICs) of established agents against filamentous fungi (molds); however, standard conditions are not available for testing their fungicidal activities (minimum fungicidal or lethal concentrations [MFCs]). This study evaluated the in vitro fungistatic and fungicidal activities of voriconazole, itraconazole, and amphotericin B against 260 common and emerging molds (174 Aspergillus sp. isolates [five species], 23 Fusarium sp. isolates [three species], 6 Paecilomyces lilacinus isolates, 6 Rhizopus arrhizus isolates, 23 Scedosporium sp. isolates, 23 dematiaceous fungi, and 5 Trichoderma longibrachiatum isolates). MICs were determined by following the NCCLS M38-P broth microdilution method. MFCs were the lowest drug dilutions that resulted in fewer than three colonies. Voriconazole showed similar or better fungicidal activity (MFC at which 90% of isolates tested are killed [MFC(90)], 1 to 2 microg/ml) than the reference agents for Aspergillus spp. with the exception of Aspergillus terreus (MFC(90) of voriconazole and amphotericin B, >8 microg/ml). The voriconazole geometric mean (G mean) MFC for Scedosporium apiospermum was lower (2.52 microg/ml) than those of the other two agents (5.75 to 7.5 microg/ml). In contrast, amphotericin B and itraconazole G mean MFCs for R. arrhizus were 2.1 to 2.2 microg/ml, but that for voriconazole was >8 microg/ml. Little or no fungicidal activity was shown for Fusarium spp. (2 to >8 microg/ml) and Scedosporium prolificans (>8 microg/ml) by the three agents, but voriconazole had some activity against P. lilacinus and T. longibrachiatum (G mean MFCs, 1.8 and 4 microg/ml, respectively). The fungicidal activity of the three agents was similar (G mean MFC, 1.83 to 2.36 microg/ml) for the dematiaceous fungi with the exception of the azole MFCs (>8 microg/ml) for some Bipolaris spicifera and Dactylaria constricta var. gallopava. These data extend and corroborate the available fungicidal results for the three agents. The role of the MFC as a predictor of clinical outcome needs to be established in clinical trials by following standardized testing conditions for determination of these in vitro values.

Amphotericin B↗
PubMed2002

Automated extraction of genomic DNA from medically important yeast species and filamentous fungi by using the MagNA Pure LC system.

A fully automated assay was established for the extraction of DNA from clinically important fungi by using the MagNA Pure LC instrument. The test was evaluated by DNA isolation from 23 species of yeast and filamentous fungi and by extractions (n = 28) of serially diluted Aspergillus fumigatus conidia (10(5) to 0 CFU/ml). Additionally, DNA from 67 clinical specimens was extracted and compared to the manual protocol. The detection limit of the MagNA Pure LC assay of 10 CFU corresponded to the sensitivity when DNA was extracted manually; in 9 of 28 runs, we could achieve a higher sensitivity of 1 CFU/ml blood, which was found to be significant (p <or= 0.004). DNA from all fungal species analyzed could be extracted and amplified by real-time PCR. Negative controls from all MagNA Pure isolations remained negative. Sixty-three clinical samples showed identical results by both methods, whereas in 4 of 67 samples, discordant results were obtained. Thus, the MagNA Pure LC technique offers a fast protocol for automated DNA isolation from numerous fungi, revealing high sensitivity and purity.

DNA, Fungal↗
PubMed1998

Molecular regulation of beta-lactam biosynthesis in filamentous fungi.

The most commonly used beta-lactam antibiotics for the therapy of infectious diseases are penicillin and cephalosporin. Penicillin is produced as an end product by some fungi, most notably by Aspergillus (Emericella) nidulans and Penicillium chrysogenum. Cephalosporins are synthesized by both bacteria and fungi, e.g., by the fungus Acremonium chrysogenum (Cephalosporium acremonium). The biosynthetic pathways leading to both secondary metabolites start from the same three amino acid precursors and have the first two enzymatic reactions in common. Penicillin biosynthesis is catalyzed by three enzymes encoded by acvA (pcbAB), ipnA (pcbC), and aatA (penDE). The genes are organized into a cluster. In A. chrysogenum, in addition to acvA and ipnA, a second cluster contains the genes encoding enzymes that catalyze the reactions of the later steps of the cephalosporin pathway (cefEF and cefG). Within the last few years, several studies have indicated that the fungal beta-lactam biosynthesis genes are controlled by a complex regulatory network, e. g., by the ambient pH, carbon source, and amino acids. A comparison with the regulatory mechanisms (regulatory proteins and DNA elements) involved in the regulation of genes of primary metabolism in lower eukaryotes is thus of great interest. This has already led to the elucidation of new regulatory mechanisms. Furthermore, such investigations have contributed to the elucidation of signals leading to the production of beta-lactams and their physiological meaning for the producing fungi, and they can be expected to have a major impact on rational strain improvement programs. The knowledge of biosynthesis genes has already been used to produce new compounds.

Anti-Bacterial Agents↗
PubMed1995

Chromosome-length polymorphism in fungi.

The examination of fungal chromosomes by pulsed-field gel electrophoresis has revealed that length polymorphism is widespread in both sexual and asexual species. This review summarizes characteristics of fungal chromosome-length polymorphism and possible mitotic and meiotic mechanisms of chromosome length change. Most fungal chromosome-length polymorphisms are currently uncharacterized with respect to content and origin. However, it is clear that long tandem repeats, such as tracts of rRNA genes, are frequently variable in length and that other chromosomal rearrangements are suppressed during normal mitotic growth. Dispensable chromosomes and dispensable chromosome regions, which have been well documented for some fungi, also contribute to the variability of the fungal karyotype. For sexual species, meiotic recombination increases the overall karyotypic variability in a population while suppressing genetic translocations. The range of karyotypes observed in fungi indicates that many karyotypic changes may be genetically neutral, at least under some conditions. In addition, new linkage combinations of genes may also be advantageous in allowing adaptation of fungi to new environments.

Chromosomes, Fungal↗
PubMed1998

Correlation between the prevalence of certain fungi and sick building syndrome.

OBJECTIVE: To examine the role of fungi in the production of sick building syndrome. METHODS: A 22 month study in the United States of 48 schools (in which there had been concerns about health and indoor air quality (IAQ). Building indoor air and surface samples, as well as outdoor air samples were taken at all sites to look for the presence of fungi or their viable propagules. RESULTS: Five fungal genera were consistently found in the outdoor air and comprised over 95% of the outdoor fungi. These genera were Cladosporium (81.5%), Penicillium (5.2%), Chrysosporium (4.9%), Alternaria (2.8%), and Aspergillus (1.1%). At 20 schools, there were significantly more colony forming units per cubic metre (CFU/m3) (p < 0.0001) of propagules of Penicillium species in the air samples from complaint areas when compared with the outdoor air samples and the indoor air samples from noncomplaint areas. At five schools, there were more, although not significant (p = 0.10), Penicillium propagules in the air samples from complaint areas when compared with the outdoor air samples and the indoor air samples from noncomplaint areas. In 11 schools, the indoor air (complaint areas) fungal ratios were similar to that in the outdoor air. In these 11 schools Stachybotrys atra was isolated from swab samples of visible growth under wetted carpets, on wetted walls, or behind vinyl wall coverings. In the remaining 11 schools, the fungal ratios and CFU/m3 of air were not significantly different in different areas. Many of the schools took remedial action that resulted in an indoor air fungal profile that was similar to that outdoors. CONCLUSIONS: Propagules of Penicillium and Stachybotrys species may be associated with sick building syndrome.

Air Microbiology↗
PubMed1990

Involvement of fungi and bacteria in enhanced and nonenhanced biodegradation of carbendazim and other benzimidazole compounds in soil.

The relationship between chemical structure and the enhancement of microbial degradation of three benzimidazole compounds in soil was determined. Preapplication of methyl benzimidazole-2-ylcarbamate (carbendazim or MBC), 2-aminobenzimidazole (2AB), and benzimidazole enhanced their degradation upon repeated application (self-enhanced degradation). MBC and 2AB cross-enhanced the degradation of each of these two compounds, whereas benzimidazole did not enhance the degradation of MBC. Thiabendazole (TBZ) did not enhance its own degradation or cross-enhance the degradation of MBC. No increase in the number of MBC-degrading fungi or in the capacity of soilborne fungi to degrade MBC was detected in soil exhibiting enhanced MBC degradation (MBC-history). A sharp increase in esterolytic activity in the microsomal fraction of Alternaria alternata capable of degrading MBC in culture was induced by the presence of MBC in the growth medium. 2AB was the main metabolite of MBC that accumulated in A. alternata cultures and in cell-free preparations. MBC was degraded much faster by mixed bacterial cultures that originated from MBC-history soil than in cultures from MBC-nonhistory soil. Fluctuations in the MBC degrading capacity of mixed bacterial cultures occurred during repeated subculturing of the mixed culture. Inoculation of nonhistory soil with mixed bacterial cultures resulted in enhanced MBC degradation, whereas inoculation with A. alternata did not enhance MBC degradation. It is suggested that while fungi contribute to MBC dissipation in soil, bacteria have a greater role in enhanced biodegradation of MBC in soil.

Acremonium↗
PubMed1990

Isolation and characterization of cellulolytic anaerobic fungi and associated mycoplasmas from the rumen of a steer fed a roughage diet.

The isolation of 12 strains of cellulolytic fungi from the rumen of a roughage-fed steer is described. These represented three different genera, including one new genus and species (Orpinomyces bovis). The organisms were indistinguishable on the basis of fermentation products from cellulose, and their fermentation patterns were very similar to those of rumen fungi isolated in other countries. Mycoplasmas were found to be associated with 7 of the 12 isolates. The ecological role of the association of the mycoplasmas with rumen fungi is still unknown.

Anaerobiosis↗
PubMed2001

Endophytic fungi from Amomum siamense.

Endophytic fungi were isolated from apparently healthy organs of the wild ginger Amomum siamense Criab.. including leaves, pseudostems, and rhizomes, collected from two sites in Doi Suthep-Pui National Park, Thailand. Endophytes were relatively common with an isolate prevalence of 70%-83% at the two sites sampled in the wet and dry seasons. The endophyte assemblages from the two sites were diverse and comprised 7 Ascomycetes and 26 mitosporic fungi. Colletotrichum "gloeosporioides" (Penz.) Penz. & Sacc. in Penz., Glomerella spp., xylariaceous fungi, and Phomopsis spp. were consistently dominant as endophytes on Amomum siamense, but many rare species and mycelia sterilia were also recorded. There was no significant difference between the number of isolates recovered from leaves containing vein tissues and those containing intervein tissues, independent of leaf age. Most taxa showed a preference for either leaf tissue or pseudostems. Two new Ascomycetes species. Gaeumannomyces amomi and Leiosphaerella amomi, were discovered from leaves and rhizomes, respectively, and four species of Pyricularia, including three new species, were isolated from leaves.

Fungi↗
PubMed1987

Specific and rapid identification of medically important fungi by exoantigen detection.

Within a decade of its introduction, the exoantigen technique has won general acceptance for accurate and rapid identification of fungal pathogens. This acceptance is emphasized by the fact that positive exoantigen results obtained with the dimorphic pathogenic fungi B. dermatitidis, C. immitis, H. capsulatum varieties capsulatum, duboisii, and farciminosum, and P. brasiliensis are no longer considered presumptive evidence but are considered definitive data for species identification. Technical problems associated with poor sensitivity and false-positives in some of the early tests have been resolved. The test expands the diagnostic capabilities of the laboratory. We encourage the establishment of libraries of antisera for species identification and, where appropriate, for serotyping. Since the test is simple and reagents for many of the pathogens are commercially available, the test can be performed in most laboratories. As highly defined antigens are produced, more standardized and specific tests will be developed. Hybridoma technology may provide the means for producing specific antibodies without the need for highly purified antigens, which have been difficult to produce. The identification of numerous fungi could be facilitated by application of exoantigen techniques. Specific antisera should be developed to achieve this goal and to obtain antigenic data useful for elucidating taxonomic relationships. Some fungi cannot be classified on the basis of morphologic and biochemical qualities alone. Supplementary data obtained with exoantigen analyses could undoubtedly aid in resolving such problems.

Antigens, Fungal↗
PubMed2001

Homology-dependent gene silencing mechanisms in fungi.

Homology-dependent gene silencing (HDGS) is a ubiquitous phenomenon among fungi, plants, and animals. Gene silencing can be triggered and can affect artificially introduced nucleic acid molecules, both DNA and RNA, and/or can act on endogenous duplicated sequences. Although the various HDGS phenomena may be related each other, probably deriving from an ancestral defense mechanism, relevant differences do exist between different HDGS mechanisms. Especially in fungi, a variety of HDGS phenomena have been uncovered during the past 10 years: Gene inactivation of duplicated sequences can be achieved either through DNA-methylation and block of transcription or through sequence-specific degradation of mRNA. Moreover, duplicated sequences can also be specifically mutagenized. Studying HDGS in fungi gives us the opportunity to study such complex mechanisms in relatively simple organisms in which both genetic and biochemical approaches can be easily used.

Fungi↗
PubMed2000

Role of Mitochondrial DNA in the Senescence and Hypovirulence of Fungi and Potential for Plant Disease Control.

The unique coenocytic anatomy of the mycelia of the filamentous fungi and the formation of anastomoses between hyphae from different mycelia enable the intracellular accumulation and infectious transmission of plasmids and mutant mitochondrial DNAs (mtDNAs) that cause senescence. For reasons that are not fully apparent, mitochondria that are rendered dysfunctional by so-called "suppressive" mtDNA mutations proliferate rapidly in growing cells and gradually displace organelles that contain wild-type mtDNA molecules and are functional. The consequence of this process is senescence and death if the suppressive mtDNA contains a lethal mutation. Suppressive mtDNA mutations and mitochondrial plasmids can elicit cytoplasmically transmissible "mitochondrial hypovirulence" syndromes in at least some of the phytopathogenic fungi. In the chestnut-blight fungus Cryphonectria parasitica, the pattern of asexual transmission of mutant mtDNAs and mitochondrial plasmids resembles the pattern of "infectious" transmission displayed by the attenuating virus that is most commonly used for the biological control of this fungus. At least some of the attenuating mitochondrial hypovirulence factors are inherited maternally in crosses, whereas the viruses are not transmitted sexually. The natural control of blight in an isolated stand of chestnut trees has resulted from the invasion of the local population of C. parasitica by a senescence-inducing mutant mtDNA. Moreover, a mitochondrial plasmid, pCRY1, attenuates at least some virulent strains of C. parasitica, suggesting that such factors could be applied to control plant diseases caused by fungi.

fungi↗
PubMed2003

Of smuts, blasts, mildews, and blights: cAMP signaling in phytopathogenic fungi.

cAMP regulates morphogenesis and virulence in a wide variety of fungi including the plant pathogens. In saprophytic yeasts such as Saccharomyces cerevisiae, cAMP signaling plays an important role in nutrient sensing. In filamentous saprophytes, the cAMP pathway appears to play an integral role in vegetative growth and sporulation, with possible connections to mating. Infection-related morphogenesis includes sporulation (conidia and teliospores), formation of appressoria, infection hyphae, and sclerotia. Here, we review studies of cAMP signaling in a variety of plant fungal pathogens. The primary fungi to be considered include Ustilago maydis, Magnaporthe grisea, Cryphonectria parasitica, Colletotrichum and Fusarium species, and Erisyphe graminis. We also include related information on Trichoderma species that act as mycoparasites and biocontrol agents of phytopathogenic fungi. We point out similarities in infection mechanisms, conservation of signaling components, as well as instances of cross-talk with other signaling pathways.

Cyclic AMP↗
PubMed2003

Establishment of biotrophy by parasitic fungi and reprogramming of host cells for disease resistance.

Parasitic biotrophs such as mildews and rusts evolved specific mechanisms that keep host cells alive during infection. These fungi appear to absorb nutrients mainly by proton-symport-driven transporter proteins that reside in specialized feeding structures. Accumulating evidence suggests that biotrophic fungi both suppress induction of plant defense responses in physical proximity to infection sites and induce specific host genes for the establishment of biotrophy. The peculiarities of biotrophic pathogenesis likely reflect diverse types of plant disease-resistance responses. The cloning of race-specific resistance genes to powdery mildew infection and of genes required for their function provides first insights into molecular mechanisms enabling the host to recognize mildew effector components and suggests candidate mechanisms of resistance signaling. Resistance to powdery mildew fungi that result from mutations in host genes promises to shed light on mechanisms that are required for the establishment of disease susceptibility.

Alleles↗
PubMed2006

Biology of flower-infecting fungi.

The ability to infect host flowers offers important ecological benefits to plant-parasitic fungi; not surprisingly, therefore, numerous fungal species from a wide range of taxonomic groups have adopted a life style that involves flower infection. Although flower-infecting fungi are very diverse, they can be classified readily into three major groups: opportunistic, unspecialized pathogens causing necrotic symptoms such as blossom blights (group 1), and specialist flower pathogens which infect inflorescences either through the gynoecium (group 2) or systemically through the apical meristem (group 3). This three-tier system is supported by life history attributes such as host range, mode of spore transmission, degree of host sterilization as a result of infection, and whether or not the fungus undergoes an obligate sexual cycle, produces resting spores in affected inflorescences, and is r- or K-selected. Across the three groups, the flower as an infection court poses important challenges for disease management. Ecologically and evolutionarily, terms and concepts borrowed from the study of venereal (sexually transmitted) diseases of animals do not adequately capture the range of strategies employed by fungi that infect flowers.

Flowers↗
PubMed2005

Domestic exposure to fungi and total serum IgE levels in asthmatic children.

We measured the number of airborne, viable fungi and house dust mite (HDM) allergen levels in the homes of a group of asthmatic children. Blood samples were drawn and the amounts of total and specific serum IgE were determined. The association between the number of fungal colonies, dust mite allergen exposure, and specific and total IgE was evaluated. The number of viable airborne fungi was high (20,543 CFU/m(3)) in those investigated houses. Der p1 concentrations on child's mattress exceeding 2 microg/g were found in 78.6% of the houses. A quantitative dose-response relationship was demonstrated between the exposure to viable, airborne molds and the amount of total IgE (r = 0.4399 and P = .0249) and the level was further increased in children with coexposure to viable fungi and HDM.

Allergens↗
PubMed2001

Identification of thermophilic and mesophilic bacteria and fungi in Esfahan (Iran) municipal solid waste compost.

The thermophilic and mesophilic microbiota in compost produced from Esfahan municipal solid waste were examined at different stages of composting process from day zero to 28 days and was conducted in four different seasons. Some of the mesophilic bacteria observed in initial stages of composting process were gram negative Escherichia, Klebsiella, Aeromonas and Alcaligenes, and gram positive Enterococcus and Bacillus species. After 20 days of the composting process lower species diversity of mesophiles (only Bacillus species) were isolated, which was most likely due to the high temperature (60-68 degrees C) condition. Some of the observed thermophilic bacteria at later stages of the process are: Bacillus subtilis, B. polymyxa, B. pumilus, B. sphaericus, and B. licheniformis from thermotolerants, and B. stearothermophilus, B. acidocaldarius, and B. schleglii from thermophiles. Among the mesophilic fungi, at the initial stages of composting process some types of yeasts and molds were isolated, but after day 20 due to high temperature condition (60-68 degrees C), no mesophilic fungi were obtained. On the 15th day of composting the highest diversity of thermotolerant fungi such as Cladosporium, Aspergillus, Mucor, Rhizopus, and Absidiae spp. were observed. The results indicated that, in order to obtain a sanitary product in cold seasons, the composting process needs a longer duration and fewer turnings.

Conservation of Natural Resources↗
PubMed2001

Bioaerosol lung damage in a worker with repeated exposure to fungi in a water-damaged building.

There has been increased concern over health effects related to potential exposure of building occupants to bioaerosols. We report the case of a worker with a respiratory illness related to bioaerosol exposure in a water-damaged building with extensive fungal contamination. We performed environmental tests to evaluate potential exposure to fungi, and we used mycotoxin-specific IgG antibody in serologic studies in the attempt to evaluate exposure to mycotoxins. Extensive fungal contamination was documented in many areas of the building. Penicillium, Aspergillus, and Stachybotrys species were the most predominant fungi found in air sampling. Our serologic test was not useful in differentiating workers who were probably occupationally exposed to mycotoxins from those who were not; however, it did yield evidence that individuals may make specific IgG antibodies to macrocyclic tricothecene mycotoxins. Further research is needed concerning health effects related to bioaerosol exposures, particularly regarding markers of exposure to specific fungi that may produce mycotoxins. In the absence of clinical tools specific for evaluation of mycotoxin-related illness, a systematic clinical approach for evaluating persons with suspected building-related respiratory illness is warranted.

Aerosols↗