PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Microbial Viability”

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 109 records · Page 6Linked to original sources
PubMed1992

The endodontic microflora revisited.

The microbial flora of 35 dental root canals were examined, taking care to maintain the viability of obligate anaerobes which accounted for 45% of total isolations, while streptococcal species accounted for 24% of the total species isolated. Individual root canals yielded a maximum of eight bacterial species. A total of 40 different species was isolated of which the most prevalent were the facultative anaerobe Streptococcus sanguis and the obligate anaerobe, Peptostreptococcus micros (both in 23% of root canals), followed by Eubacterium aerofaciens and the 'Streptococcus milleri group' (both 17%) then Prevotella melaninogenica (formerly Bacteroides melaninogenicus), Enterococcus faecalis and Prevotella oralis (formerly Bacteroides oralis), which were each isolated from 14% of root canals. Highly significant associations were discovered between four pairs of species, viz P. melaninogenica with P. micros, P. melaninogenica with P. oralis, Prevotella corporis with Streptococcus morbillorum and Actinomyces odontolyticus with E. faecalis.

Dental Pulp Cavity↗
PubMed1996

Microbial contamination of antiseptics and disinfectants.

BACKGROUND: There have been a number of reports on microbial contamination of antiseptics and disinfectants. At present, however, the necessity of measures to prevent contamination do not seem to be fully appreciated. We investigated microbial contamination of antiseptics and disinfectants that are used in our hospital. METHODS: Fifty-one samples of benzalkonium chloride and chlorhexidine gluconate that were being used in the hospital were examined. Viability of the contaminants detected in these samples was also tested in the agents. Then we examined measures to prevent contamination of these agents. RESULTS: Microbial contamination was detected at 10(2) to 10(7) CFU/ml in the following samples: 6 of 23 samples of cotton balls soaked in 0.02% benzalkonium chloride kept in a canister for antisepsis and disinfection (26.1%); 7 of 13 samples of 0.02%, benzalkonium chloride or 0.02% chlorhexidine gluconate in an irrigation apparatus kept at 37 degrees C for vaginal douching (53.8%); and 9 of 15 samples of 0.02% benzalkonium chloride or 0.05% chlorhexidine gluconate for storage of suction catheters in a plastic bottle (60%). The major contaminants were Burkholderia cepacia, Pseudomonas aeruginosa, Xanthomonas maltophilia, and Pseudomonas fluorescens. The first two organisms examined grew in the agents. After improvements in the handling of the antiseptics and disinfectants, no microbial contamination was observed. CONCLUSIONS: It is necessary to check microbial contamination of diluted benzalkonium chloride and diluted chlorhexidine gluconate that are in use. Such products are not recommended as antiseptics.

Anti-Infective Agents, Local↗
PubMed1993

Application of flow cytometry to rapid microbial analysis in food and drinks industries.

In food and drinks industries, the time required for conventional tests can lead to substantial delays in product release to the market. Flow cytometry (FCM) has been used in conjunction with viability markers for rapid counting of yeast, mould and bacterial cells in food products. A single-parameter flow cytometer has proved applicable to the rapid detection of low numbers of microbial contaminants in finished products. The excellent correlation between FCM results and product quality shelf-life expiry date has allowed the establishment of realistic quality control criteria for rapid positive release of product. Used for the monitoring of microbial biomass during manufacturing processes, flow cytometry allowed a direct assessment of bacterial growth. The reproducibility of the results and the proven correlation with standard plate count method obtained in industrial conditions make FCM a good predictive method for product and process quality control.

Bacteria↗
PubMed1999

The Erlanger silver catheter: in vitro results for antimicrobial activity.

The antimicrobial activity of a silver-impregnated polymer catheter (the Erlanger silver catheter) was demonstrated by determining the microbial adhesion to the surface of the catheter and by measuring the rate of proliferation (viability) of microorganisms at this site. On the surface of a catheter impregnated with silver, according to previously described methods, the bacterial adhesion of Staphylococcus epidermidis is reduced by 28-40%. Bacterial proliferation on the surface of the catheter and biofilm production are also substantially reduced by the elution of free silver ions from the catheter matrix. Bacteriostatic and bactericidal activities can be determined. The antimicrobial efficacy of the silver catheter is not reduced by blood components. There is no loss in antimicrobial activity for weeks after preincubation in water or phosphate buffered saline. The antimicrobial activity depends on the extent of the active silver surface.

Animals↗
PubMed1998

Inactivation of bacteriophage lambda, Escherichia coli, and Candida albicans by ozone.

The effects of ozone (O3) on three types of microbes were studied. Test suspensions were exposed to 600 ppm O3 at room temperature. Control experiments were performed under identical conditions using oxygen gas. Bacteriophage lambda was completely inactivated at 10 min while Escherichia coli and Candida albicans were only inactivated by factors of 10(5) and 10(4) respectively at 40 min. Exposure of a mixed microbial suspension to O3 for 5 min resulted in 100% killing of bacteriophages while the viability of E. coli remained unchanged. Various body fluids containing phages were exposed to O3. Compared to buffered solution, the decrease in phage titers was significantly slower in whole blood, plasma, and albumin. Both E. coli and C. albicans had increased production of thiobarbituric-acid-reactive substances with increased O3 exposure. 3H-labelled amino acids were incorporated into E. coli. O3 treatment resulted in a loss of radioactivity, indicating leakage of cytoplasmic contents. The data indicate that microbes are inactivated by O3 at different rates, possibly related to differential membrane permeability. The milieu in which microbes are present determines the effectiveness and outcome of O3 treatment.

Bacteriophage lambda↗
PubMed1968

Isolation of mutants of Euglena gracilis with impaired photosynthesis.

Four mutant strains of Euglena gracilis have been isolated after treatment of wild type cells with ultraviolet light or the chemical mutagen nitrosoguanidine. None of the mutants is capable of autotrophic growth or photosynthetic carbon dioxide fixation. The mutant strains contain normal amounts of the enzymes of the reductive pentose phosphate cycle and are qualitatively similar to the wild type in pigment composition, but are unable to carry out the Hill reaction (light induced reduction of 2,6-dichlorophenol indophenol). Isolated mutant plastids cannot photoreduce NADP with water as the electron donor but can carry out this reaction when the electron donating system is ascorbate and 2,6-dichlorophenol indophenol. Whole cells of the mutants show the light induced oxidation of cytochrome f by light reaction I but are unable to bring about cytochrome f reduction by light reaction II. The mutants appear to be blocked at or near light reaction II in the photosynthetic electron transport chain. The mutants may represent alterations of the chloroplast genome since the mutation isolation was carried out under conditions where chloroplast viability was severely impaired, but cell viability was unaffected.

Euglena↗
PubMed1993

Bacterial growth in isoflurane vapour.

Pathogenic bacteria were grown on nutrient agar in a mixture of air and isoflurane vapour, and in air alone. The presence of isoflurane vapour in concentrations considerably in excess of those used either for anaesthesia or for sedation in intensive care had no effect either on the rate of bacterial growth or on the viability of colony forming units.

Colony Count, Microbial↗
PubMedDate not supplied

[Effect of various methods of immobilization on stability of a microbial biosensor based on Pseudomonas rathonis T during detection of surfactants].

The operating and storage stability of a receptor element of an amperometric biosensor based on the Pseudomonas rathonis strain T capable of degrading surfactants was tested. Microbial cells were immobilized by incorporation in gels (agar, agarose, and calcium-alginate), polyvinyl alcohol membrane, adhesion to the chromatographic paper GF/A, or by the cross-linking induced by glutaric aldehyde. Incorporation of microbial cells in agar gel provides the long-standing conservation of their activity and viability during measurements of high concentrations of surfactants and allows the receptory element of the biosensor to be rapidly recovered after the measurements.

Biosensing Techniques↗
PubMed2000

Flow cytometric analysis of microorganisms.

The application of flow cytometry to microorganisms is as old as the technique itself, but it has historically been underexploited for microbial applications. This is now being reversed and microbiologists are ideally placed to benefit from recent technological advances. While earlier papers demonstrated the use of flow cytometry for studies of viability and taxonomy, recent developments in bioinformatics and reporter gene technologies are leading to novel applications in microbiology. Variants of green fluorescent protein have been used for the study of conditional microbial gene regulation in medically important host-pathogen interactions and fluorescence-activated cell sorting is being applied to the isolation of novel mutants in directed evolution studies. This paper reviews the reasons for the delay in the application of flow cytometry to microbial problems, the range of applications, and their limitations and considers the progress made in developing new strategies for use in microbiological investigations.

Bacteria↗
PubMed1983

Sodium hypochlorite decontamination of split-thickness cadaveric skin infected with bacteria and yeast with subsequent isolation and growth of basal cells to confluency in tissue culture.

The ability of sodium hypochlorite to decontaminate skin while leaving sufficient epidermal cell viability for growth in tissue culture was investigated with an in vitro system. Split-thickness cadaveric skin was infected with Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans and subsequently treated with various concentrations of sodium hypochlorite for various time intervals. Exposure to a 0.5% solution of sodium hypochlorite for 6 min effectively decontaminated the skin while leaving 66% of the basal cells viable. The basal cells were subsequently grown to confluency in tissue culture. This study demonstrates that microbial colonization of skin can be eliminated by exposure to dilute hypochlorite. This procedure, while decontaminating the skin, leaves sufficient viability of epidermal cells for subsequent growth and expansion in tissue culture, elements essential for grafting over wounds.

Bacteria↗
PubMed1996

Improving production of aromatic compounds in Escherichia coli by metabolic engineering.

The efficiency of conversion of raw material to product is a major factor controlling the commercial viability of large-scale fermentation processes for the production of metabolites. Traditional approaches to developing microbial strains for metabolite overproduction have relied on amplifying only the enzymatic steps within the specific biosynthetic pathway of a desired product. While this approach has generally been successful for reaching high product concentrations and yields, further improvements (and hence reduced manufacturing cost) can only be achieved by redirecting carbon flux from central metabolism to the product-forming pathway. Such manipulation of central metabolic pathways promises to deliver a new generation of metabolite-producing microorganisms.

Amino Acids↗
PubMed1985

Hepatocyte function in sepsis: Kupffer cells mediate a biphasic protein synthesis response in hepatocytes after exposure to endotoxin or killed Escherichia coli.

Alterations in hepatic function are seen in sepsis and/or multiple system organ failure. We hypothesized that Kupffer cells (KC) within the liver may mediate functional alterations in adjacent hepatocytes (HC) in response to bacterial products. We have previously described decreases in rat HC protein synthesis during in vitro cocultivation with peritoneal macrophages in the presence of gentamicin-killed Escherichia coli (GKEC) or endotoxin (LPS). The present studies demonstrate that purified (greater than 95%), syngeneic, or allogeneic KC exposed to GKEC or LPS impart a biphasic response in cultured HC. When HC were cultured alone there was no alteration in 3H-leucine incorporation into HC protein after the addition of GKEC or LPS. When HC were cocultured with KC there was increased protein synthesis compared with HC alone (p less than 0.001). After the addition of GKEC or LPS there was an immediate increase in coculture HC protein synthesis. However, a marked decrease in coculture protein synthesis was seen 16 degrees later (p less than 0.001). To ensure that KC alone were responsible, splenic lymphocytes were added to HC alone or HC/KC coculture, but they did not alter the results. HC viability and appearance were unchanged throughout the experiments. These results show that exposure of KC to microbial products can profoundly alter HC function and support the concept of local KC modulation of HC function during sepsis.

Animals↗
PubMed1975

Effects of human and rabbit serum on viability, permeability, and envelope lipids of Serratia marcescens.

The major action of serum on gram-negative organisms is thought to be on the microbial envelope. We compared the effects of normal human and rabbit serum on the envelope lipids of two strains of Serratia marcescens, one sensitive and one resistant to the bactericidal effects of serum. During killing by either serum, the sensitive strain underwent rapid permeability changes coincident with degradation of microbial phospholipids. The resistant strain exhibited none of these effects. The phospholipid degradation that accompanies killing of the sensitive strain by serum could be caused by phospholipases present in serum or by Serratia's own phospholipid-splitting enzymes. The results indicate that phospholipid breakdown is caused by activation of bacterial of bacterial phospholipases and not by serum phospholipases. This conclusion is based upon the following findings.(i1 Although rabbit serum phospholipase A was at least 10 times more active than human serum phospholipase A, phospholipid degradation in the sensitive Serratia strain was comparable during (equally rapid) killing by human or rabbit serum. (ii) Heat treatment (56 C) of both sera eliminated bactericidal activity as well as microbial lipid degradation but abolished phospholipase activity of human serum only. (iii) Virtually complete removal of phospholipase A activity from human serum by adsorption onto autoclaved Micrococcus lysodeikticus had no effect on the extent of phospholipid hydrolysis or on bactericidal activity. Activation by serum of endogenous phospholipase activity in S. marcescens was accompanied by enhanced incorporation of lipid precursors into bacterial lipids. No evidence was found for increased turnover of protein or ribonucleic acid during killing by serum.

Alkaline Phosphatase↗
PubMedDate not supplied

[Prediction of microorganism resistance to the immobilization process in polyacrylamide gel].

It is shown that the immobilization of bacterial cells in polyacrylamide gel or their exposure to monomer acrylamide results in a quantitatively similar decrease of their viability. It is indicated that acrylamide treatment may be used as a test for measuring the resistance of microbial populations to polyacrylamide gel immobilization and predicting the survival rate of microorganisms incorporated.

Acrylic Resins↗