SEARCH · PubMed Health

Results for “microbial detection”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,009 records · Page 56Linked to original sources

PubMed1981

[Streptococcus pneumoniae interaction with continuous human cell lines].

The in vitro model of pneumococcal infection, using continuous mammalian cell lines, is proposed. Two different types of interaction between bacteria and eucaryotic cells are described: the intracellular ingestion of bacteria or their proliferation on the surface of the cellular monolayer, these different types of interaction being characteristic of different cell lines. In case of the proliferation of bacteria on the surface of the monolayer the forms, morphologically similar to the stages of microbial L-transformation, have been detected.

Adsorption↗

PubMed1994

[Health risks of mycotoxins for humans].

Fungi cause diseases in humans in different ways. Due to production of secondary metabolites by molds, dematiaceous hyphomycetes, and primary plant pathogenic fungus species intoxications are included in their pathogenic potency. Mycotoxins mostly enter the body by ingestion of food because they are contaminants of plant products and in case of carry over also of animal products. Recent investigations have shown that mycotoxins detected in feed and food during microbial deterioration can also be produced inside warm-blooded organism, e. g. with aspergillosis in animals (mammals and birds). This means an enhanced risk for humans to suffer from mycotoxicosis, in which the toxic agent has an exogenic or endogenic source. Therefore, attention should be paid to the fact that mycotoxins are not only damaging cells; they very often possess a genotoxic potential.

Animals↗

PubMed1997

[Molecular mimicry and mechanisms of autoantibody production].

Molecular mimicry is defined as similar structures shared by products of dissimilar genes. This review article discusses a possible role of molecular mimicry in the production of autoantibodies. Antibodies reactive with products of bacterial and viral genes sometime cross-react with normal cellular proteins. Sera from patients with systemic autoimmune diseases show crossreactivity with some bacterial and/or viral gene products at a significant frequency. Identification of the structures of antigenic epitopes recognized by disease-associated autoantibodies by expression cloning of autoantigen molecules and gene fragment expression revealed the amino acid residues that are shared by autoantibody-defined epitopes and microbial proteins. The presence of amino acid sequences shared between microbial proteins and autoantigens and the detection of antibodies in patients' sera that bind to the crossreactive epitopes suggest that immune responses to bacterial and viral infections may initiate the production of autoantibodies. Receptor-mediated phagocytosis of autoantigen molecules by crossreactive B cells and subsequent antigen presentation to helper T cells may facilitate the production of autoantibodies reactive with separate epitopes, if the autoantigen complex contains multiple B-cell epitopes and a shared T helper cell epitope. Analyses of the fine specificity of T helper cell epitopes on Friend murine leukemia virus env gene products revealed unexpected heterogeneity and redundancy of T cell responses even to a single epitope. This heterogeneity in T cell responses might play a role in the activation of self-reactive T helper cells through molecular mimicry.

Animals↗

PubMed2004

DNA vaccines to attack cancer.

Delivery of antigens by injection of the encoding DNA allows access to multiple antigen-presenting pathways. Knowledge of immunological processes can therefore be used to modify construct design to induce selected effector functions. Expression can be directed to specific intracellular sites, and additional genes can be fused or codelivered to amplify responses. Therapeutic vaccination against cancer adds a requirement to overcome tolerance and to activate a weakened immune repertoire. Induction of CD4(+) T helper cells is critical for both antibody and T cell effector responses. To activate immunity against tumor antigens, we fused the tumor-derived sequences to genes encoding microbial proteins. This strategy engages T helper cells from the large antimicrobial repertoire for linked help for inducing antibody against cell-surface tumor antigens. The principle of linked T cell help also holds for induction of epitope-specific antitumor CD8(+) T cells, but the microbial sequence has to be minimized to avoid competition with tumor antigens. Epitope-specific DNA vaccination leads to powerful antitumor attack and can activate immunity from a profoundly tolerized repertoire. Vaccine designs validated in preclinical models are now in clinical trial with immune responses detected against both tumor antigens and fused microbial antigens. DNA priming is highly efficient, but boosting may benefit from increased antigen expression. Physical methods including electroporation provide increased expression without introducing additional competing antigens. A wide range of cancers can be targeted, and objective assays of response will determine efficacy.

Animals↗

PubMed1980

Variation in microbial activity in histosols and its relationship to soil moisture.

Microbial biomass, dehydrogenase activity, carbon metabolism, and aerobic bacterial populations were examined in cropped and fallow Pahokee muck (a lithic medisaprist) of the Florida Everglades. Dehydrogenase activity was two- to sevenfold greater in soil cropped to St. Augustinegrass (Stenotaphrum secundatum (Walt) Kuntz) compared with uncropped soil, whereas biomass ranged from equivalence in the two soils to a threefold stimulation in the cropped soil. Biomass in soil cropped to sugarcane (Saccharum spp. L) approximated that from the grass field, whereas dehydrogenase activities of the cane soil were nearly equivalent to those of the fallow soil. Microbial biomass, dehydrogenase activity, aerobic bacterial populations, and salicylate oxidation rates all correlated with soil moisture levels. These data indicate that within the moisture ranges detected in the surface soils, increased moisture stimulated microbial activity, whereas within the soil profile where moisture ranges reached saturation, increased moisture inhibited aerobic activities and stimulated anaerobic processes.

Journal Article↗

PubMed2001

Microbial activity in aquatic environments measured by dimethyl sulfoxide reduction and intercomparison with commonly used methods.

A new method to determine microbial (bacterial and fungal) activity in various freshwater habitats is described. Based on microbial reduction of dimethyl sulfoxide (DMSO) to dimethyl sulfide (DMS), our DMSO reduction method allows measurement of the respiratory activity in interstitial water, as well as in the water column. DMSO is added to water samples at a concentration (0.75% [vol/vol] or 106 mM) high enough to compete with other naturally occurring electron acceptors, as determined with oxygen and nitrate, without stimulating or inhibiting microbial activity. Addition of NaN(3), KCN, and formaldehyde, as well as autoclaving, inhibited the production of DMS, which proves that the reduction of DMSO is a biotic process. DMSO reduction is readily detectable via the formation of DMS even at low microbial activities. All water samples showed significant DMSO reduction over several hours. Microbially reduced DMSO is recovered in the form of DMS from water samples by a purge and trap system and is quantified by gas chromatography and detection with a flame photometric detector. The DMSO reduction method was compared with other methods commonly used for assessment of microbial activity. DMSO reduction activity correlated well with bacterial production in predator-free batch cultures. Cell-production-specific DMSO reduction rates did not differ significantly in batch cultures with different nutrient regimes but were different in different growth phases. Overall, a cell-production-specific DMSO reduction rate of 1.26 x 10(-17) +/- 0. 12 x 10(-17) mol of DMS per produced cell (mean +/- standard error; R(2) = 0.78) was calculated. We suggest that the relationship of DMSO reduction rates to thymidine and leucine incorporation is linear (the R(2) values ranged from 0.783 to 0.944), whereas there is an exponential relationship between DMSO reduction rates and glucose uptake, as well as incorporation (the R(2) values ranged from 0.821 to 0.931). Based on our results, we conclude that the DMSO reduction method is a nonradioactive alternative to other methods commonly used to assess microbial activity.

Bacteria↗

PubMed1999

A new direct microscopy based method for evaluating in-situ bioremediation.

A new epifluorescent microscopy based method using 5-cyano-2, 3-ditolyl tetrazolium chloride (CTC) and 5-(4,6-dichlorotriazinyl) aminofluoroscein (DTAF) was developed for quantifying total microbial biomass and evaluating levels of microbial activity. CTC is a tetrazolium dye that forms fluorescent intracellular formazan when biologically reduced by components of the electron transport system and/or dehydrogenases of metabolically active bacteria. DTAF is a fluorescein-based fluorochrome that selectively stains bacterial cell walls thereby enabling quantification of total bacterial biomass. CTC can be used in conjunction with DTAF to provide the optical resolution necessary to differentiate metabolically active cells from inactive cells in microbial populations associated with subsurface soils. The CTC/DTAF staining method has been shown to be effective for quantifying the metabolic activity of not only aerobic bacteria, but also diverse groups of anaerobic bacteria. This method allows for the rapid quantification of total and active bacterial numbers in complex soil samples without enrichment or cell elution. In this study, CTC/DTAF staining was applied to evaluate in-situ microbial activity in petroleum hydrocarbon contaminated subsurface soils from Sites 3 and 13 at Alameda Point, CA. At each site, subsurface microbial activity at two locations within contaminated plumes were examined and compared to activity at two geologically similar but uncontaminated background locations. Significant bacterial populations were detected in all soils examined, and the biomass estimates were several orders of magnitude higher than those obtained by conventional culture-based techniques. Both the total bacterial concentrations and the numbers of active bacteria in soils from contaminated areas were substantially higher than those observed in soils from background locations. Additionally, the percentages of metabolically active bacteria in the contaminated areas were consistently higher than those detected in background areas, suggesting that the enhanced microbial activity was due to microbial contaminant degradation. Although conventional heterotrophic plate counts failed to show significant microbial activity at either of the sites, soil gas carbon dioxide and methane measurements confirmed that hydrocarbon contaminant degradation was occurring in both areas. The CTC/DTAF staining protocol proved to be a rapid, reliable, and inexpensive method to evaluate the progress of in-situ bioremediation.

Bacteria↗

PubMed2001

Gene expression monitoring in soils by mRNA analysis and gene lux fusions.

Two methods recently developed to monitor the gene expression of microbial communities in soil are the extraction and detection of messenger RNA from soil microorganisms and the construction and use of lux-based bioreporter strains. The goal of these approaches is to assess microbial activity in natural and impacted soil environments.

Artificial Gene Fusion↗

PubMed2002

Protein microarrays: from serodiagnosis to whole proteome scale analysis of the immune response against pathogenic microorganisms.

Microbial diseases remain the most common cause of global mortality and morbidity. Scientific and technical achievements have dramatically improved the possibilities of investigating the humoral immune response against the whole proteome of microbial organisms. A number of genomes of microbial organisms responsible for diseases of worldwide medical importance such as Plasmodium, Toxoplasma, Mycobacterium, Streptococcus, Neisseria, Salmonella, Borrelia, and Rickettsia species have already been sequenced or will be available in the very near future. High-throughput assays such as protein microarrays have been clinically validated in serum for detecting the presence of antibodies directed against microbial antigens. Computational technologies for processing large sets of data are rapidly being developed. Such a powerful combination of genomic information and assays now offers the opportunity to identify the microbial antigens that, either alone or in combination, function as targets of natural acquired immunity against infectious diseases. This information will prove invaluable for developing vaccines against a series of microorganisms of medical relevance that are urgently needed, e.g., malaria. Additional applications of these technologies include the development of a microbial antigen array for the early serodiagnosis of both common and rare infectious diseases. This review will focus on technical and scientific issues concerning the use of antigen microarrays for vaccine development and the serodiagnosis of infectious diseases.

Antigens↗

PubMed2005

Effects of sulfonamide and tetracycline antibiotics on soil microbial activity and microbial biomass.

Increasingly often soil residual concentrations of pharmaceutical antibiotics are detected, while their ecotoxic relevance is scarcely known. Thus, dose related effects of two antibiotics, sulfapyridine and oxytetracycline, on microorganisms of two different topsoils were investigated. The fumigation-extracted microbial C (E(C)) and ergosterol were determined to indicate soil microbial and fungal biomass, respectively. Microbial activity was tested as basal respiration (BR), dehydrogenase activity (DHA), substrate-induced respiration (SIR), and Fe(III) reduction. The BR and DHA were uninfluenced even at antibiotic concentrations of 1000 microg g(-1). This revealed that an activation of microbial growth through nutrient substrate addition is required to test possible effects of the bacteriostatic antibiotics. In addition, the effects of both antibiotics were time dependent, showing that short-term tests were not suitable. Clear dose-response relations were determined with SIR when the short-term incubation of 4h was extended into the growth phase of the microorganisms (24 and 48 h). The Fe(III) reduction test, with a 7-d incubation, was also found to be suitable for toxicity testing of antibiotics in soils. Effective doses inhibiting the microbial activity by 10% (ED(10)) ranged from total antibiotic concentrations of 0.003-7.35 microg g(-1), depending on the antibiotic compound and its soil adsorption. Effective solution concentrations (EC(10)), calculated from distribution coefficients, ranged from 0.2 to 160 ng g(-1). The antibiotics significantly (p<0.05) reduced numbers of soil bacteria, resulting in dose related shifts in the fungal:bacterial ratio, which increased during 14 d, as determined from analysis of ergosterol and E(C). It was concluded that pharmaceutical antibiotics can exert a temporary selective pressure on soil microorganisms even at environmentally relevant concentrations.

Bacteria↗

PubMed2002

Investigation of lotic microbial aggregates by a combined technique of fluorescent in situ hybridization and lectin-binding-analysis.

A technique combining fluorescent in situ hybridization and lectin-binding-analysis (FISH-LBA) was developed and applied for the simultaneous detection of cellular components and glycoconjugates in lotic microbial aggregates (river snow). River snow aggregates were directly collected from the bulk water phase into coverslip chambers, in which the complete procedure including fixation, fluorescent in situ hybridization, lectin-binding and optical analysis by confocal laser scanning microscopy was performed. Neither autofluorescence originating from phyotosynthetic organisms nor inorganic particles did negatively interfere with the FISH-LBA technique. In river snow samples obtained from the river Elbe, Germany, distinct compartments of the river snow structure could be visualized with FITC-labelled lectins from Triticum vulgaris, Limulus polyphemus, Arachis hypogaea, Phaseolus vulgaris and Pseudomonas aeruginosa, binding to frequently occurring saccharide residues in the river snow matrix. The analysis could be performed on different levels of complexity. The combined technique visualized bacteria of different phylogenetic groups in the entire river snow structure as well as glycoconjugate components linked with various microcolonies. Different lectins stained slime layers and cell-envelopes of individual eukaryotic and prokaryotic cells. Consequently, application of the FISH-LBA technique allows the linkage between cellular and glycoconjugate identity in complex microbial communities.

Animals↗

PubMed2005

Establishing a linkage between phosphorus forms in dairy diets, feces, and manures.

Effective manure management to efficiently utilize organic wastes without causing environmental degradation requires a clear understanding of the transformation of P forms from diet to manure. Thus, the objective of this study was to establish quantitative relationships between P forms in diets, feces, and manures collected from U.S. Northeastern and Mid-Atlantic commercial dairy farms. Total P in diets ranged from 3.6 to 5.3 g kg(-1) dry matter, while the feces had higher P than diets (5.7-9.5 g kg(-1)) and manures had lower P (2.5-8.9 g kg(-1)) than feces. The farms with total dietary P of 4.8 to 5.3 g P kg(-1) had twofold higher concentrations of phytic acid (1647-2300 mg P kg(-1)) than farms with 3.6 to 4.0 g dietary P kg(-1) (844-1100 mg P kg(-1)). Much of the phytic acid in diets was converted to inorganic orthophosphate in the rumen as indicated by a reduction in phytic acid percentage from diets (32%) to feces (18%). The proportion of orthophosphate diesters (phospholipids, deoxyribonucleic acid [DNA]) was twice as high in feces (6.2-10%) as diets (2.4-5.3%) suggesting the excretion of microbial residues in feces. Phosphonates (aminoethyl phosphonates and phosphonolipids) were not seen in diets but were detected in feces and persisted in manures, which suggests a microbial origin. These organic compounds (phytic acid, phospholipids, DNA) were decomposed on storage of feces in slurry pits, increasing orthophosphate in manures by 9 to 12% of total P. These results suggest that reducing dietary P and typically storing feces in dairy farms will result in manure with similar chemical forms (primarily orthophosphate: 63-77%) that will be land applied. Thus, both the reduction of dietary P and storage of manure on farm are important for controlling solubility and bioavailability of P forms in soils and waters.

Animal Feed↗

PubMed2004

Development of a genotoxicity detection system using a biosensor.

The umu-lux test is a genotoxicity test using the two genetically modified S. typhmurium TA1535 strains (TL210 and TL210ctl) transformed with the luxCDABE (luciferase gene and fatty acid reductase genes) of Vibrio fischeri as a reporter gene. The TL210 strain detects genotoxicants and the TL210ctl strain detects cytotoxicants. In order to develop a highly sensitive, simple and rapid genotoxicity detection system, we constructed a biosensor using these immobilized strains. The biosensor consists of two immobilized microbial membranes, a sample vessel and photodetectors, and the genotoxicity detection system consists of the biosensor, an isothermal box, a photodetector and an air pump. The total measurement time for genotoxicants using this detection system is about 4 h. When 2% (v/v) DMSO was used as a control, the TL210 strain was not emitting light while the TL210ctl strain was. When 0.3 mg/l 4NQO was used as a genotoxicant, TL210 strain and TL210ctl strain were both emitting light. When HgCl2 was used as a cytotoxicant, neither the TL210 strain nor the TL210ctl strain were emitting light. Therefore, the false negative prevention function of a biosensor using the TL210ctl strain has been checked. These results show that our proposed system can correctly detect genotoxicants.

4-Nitroquinoline-1-oxide↗

PubMed1998

UCH9, a new antitumor antibiotic produced by Streptomyces: I. Producing organism, fermentation, isolation and biological activities.

We developed a microbial prescreen using Bacillus stearothermophilus NUB3620 and bacteriophage TP-68 to detect potential antitumor compounds acting on DNA or topoisomerases. During the course of screening microbial cultures for their antibacteriophage activities, we found that Streptomyces sp. isolated from a soil sample collected in Iwakuni city, Yamaguchi prefecture, Japan, produced a new antitumor antibiotic, UCH9. UCH9 was isolated from culture broth by a combination of EtOAc extraction and column chromatography. UCH9 has a new structure related to the antitumor antibiotic chromomycins. It exhibited antimicrobial activity against Gram-positive organisms. UCH9 also showed cytotoxic activity against HeLa S3 cells with an IC50 value of 13 nM and exhibited antitumor activity in vivo against mouse leukemia P388.

Animals↗

PubMed2004

Microbial diversity in biodeteriorated monuments as studied by denaturing gradient gel electrophoresis.

Studies of the microorganisms living on cultural assets and their potential damaging effects begin with an understanding of the microbial diversity present in such samples. Recently, molecular techniques have started to attract considerable interest since they do not require the culture of microorganisms in order to detect their presence. The basic protocol followed during microbial diversity analysis on cultural heritage assets utilizes electrophoretic techniques for separating highly homologous sequences. At present, Denaturing Gradient Gel Electrophoresis (DGGE) is the most frequently reported technique for separating DNA fragments during microbial diversity studies of art objects. In this report, we describe DGGE profiling techniques, show the most common applications, and present some examples of their use in microbial diversity studies on cultural heritage.

Art↗

PubMed2007

Identification of bacterial DNA markers for the detection of human fecal pollution in water.

We used genome fragment enrichment and bioinformatics to identify several microbial DNA sequences with high potential for use as markers in PCR assays for detection of human fecal contamination in water. Following competitive solution-phase hybridization of total DNA from human and pig fecal samples, 351 plasmid clones were sequenced and were determined to define 289 different genomic DNA regions. These putative human-specific fecal bacterial DNA sequences were then analyzed by dot blot hybridization, which confirmed that 98% were present in the source human fecal microbial community and absent from the original pig fecal DNA extract. Comparative sequence analyses of these sequences suggested that a large number (43.5%) were predicted to encode bacterial secreted or surface-associated proteins. Deoxyoligonucleotide primers capable of annealing to a subset of 26 of the candidate sequences predicted to encode factors involved in interactions with host cells were then used in the PCR and did not amplify markers in DNA from any additional pig fecal specimens. These 26 PCR assays exhibited a range of specificity in tests with 11 other animal sources, with more than half amplifying markers only in specimens from dogs or cats. Four assays were more specific, detecting markers only in specimens from humans, including those from 18 different human populations examined. We then demonstrated the potential utility of these assays by using them to detect human fecal contamination in several impacted watersheds.

Animals↗

PubMed1995

Evaluation of the automated Bact-Alert system for pediatric blood culturing.

The Organon Teknika BacT/Alert (Organon Teknika, Durham, NC), using the Pedi-BacT 20 mL aerobic bottle (BPBCS) was compared to the Wampole Isolator (WI) 1.5 Microbial tube (Wampole Laboratories, Cranbury, NJ), for detection and recovery of pediatric pathogens. The BPBCS continuously monitors culture bottles for changes in CO2 concentrations, while WI cultures are examined twice daily for appearance of colonial growth on agar media. Of 5,175 paired blood cultures, 383 pathogens were recovered from 606 positive cultures. There were 272 pathogens recovered by both systems, 64 from BPBCS only, and 47 from WI only. Overall recovery rates were 88% for BPBCS and 83% for WI. There was no significant difference between the two systems in detection or times to positivity of staphylococci, Enterobacteriaceae, or pseudomonads. Trends toward better recovery of streptococci (20 vs. 10) and fastidious microaerophiles (3 vs. 0) were found with BPBCS, whereas more slowly growing pathogens (Rochalimaea henselae [1], Mycobacterium avium-intracellulare [1]) were recovered by WI only, but because of their lower frequency did not achieve statistical significance. Detection of Haemophilus influenzae (14.9 hours in WI vs. 45.4 hours in BPBCS) was faster with WI. False positive plus contaminant cultures were detected in 5.9% BPBCS versus 1.5% WI. BPBCS offers detection of bacteremia at a rate comparable to WI with advantages of automation.

Autoanalysis↗

PubMed2000

Phylogenetic analysis of methanogens in sheep rumen ecosystem and detection of Methanomicrobium mobile By fluorescence in situ hybridization.

The population of methanogens in the sheep rumen microbial ecosystem was studied by using 16S rDNA cloning analysis, epifluorescence microscopy (which detects autofluorescence of a specific cofactor F420 in methanogens) and the 16S rRNA-targeted in situ hybridization technique. The 16S rDNA clone libraries were constructed by PCR amplification with an Archaea-specific primer set and partial sequencing of the clonal 16S rDNAs was done. Phylogenetic analysis indicated that the clones were affiliated with Methanomicrobium ruminantium and mobile, Methanobrevibacter smithii. Epifluorescence microscopy (F420 autofluorescence) and in situ hybridization by using a newly designed M. mobile-specific 16S rRNA-targeted oligonucleotide probe found that methanogens accounted for approximately 3.6% of total ruminal microorganisms and approximately 54% of the total methanogens were M. mobile.

Animals↗