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At least 73 records · Page 4Linked to original sources
PubMed1983

Growth of bacteria in intravenous fluids under stimulated actual-use conditions.

The growth of microorganisms in nonnutritive intravenous solutions under simulated actual-use conditions was studied. Small quantities of Pseudomonas aeruginosa, Staphylococcus aureus, and Klebsiella pneumoniae (final concentration 200-400 cells/ml) were injected into 500-ml containers (glass bottles and plastic bags) of 5% dextrose injection, 0.9% sodium chloride injection, and 5% dextrose and 0.9% sodium chloride injection. Additives (ampicillin, vitamin K, lidocaine, and vitamin B complex) were included in some i.v. solutions. Administration sets were attached to the i.v. containers, and the solutions were run into collection bottles; samples were withdrawn at 0, 1, 2, 3, 4, 5, 6, and 8 hours after contamination and plated for viable counts. Staph. aureus and K. pneumoniae remained viable in 5% dextrose injection and in 0.9% sodium chloride injection, but the numbers of these bacteria did not increase. The number of Ps. aeruginosa declined in all three solutions. In 5% dextrose and 0.9% sodium chloride injection, the number of K. pneumoniae declined but Staph. aureus maintained viability. The type of container and the drug additives had no effect on microbial growth, except that ampicillin was bactericidal to Staph. aureus. Low-level contamination of these bacteria in nonnutritive i.v. solutions under actual-use conditions does not result in large numbers of organisms within the time frame in which most solutions are administered.

Bacteria↗
PubMed1990

The effect of antibiotics that inhibit cell-wall, protein, and DNA synthesis on the growth and morphology of Legionella pneumophila.

The response of Legionella pneumophila to antibiotics that inhibit cell-wall, protein and DNA synthesis was examined by electronmicroscopy, MIC estimations and viable counts. Ampicillin, cefotaxime, methicillin, erythromycin, rifampicin and ciprofloxacin, each used separately at 20 times their respective MIC values, showed activity against L. pneumophila in these studies. The inhibitors of cell-wall synthesis--ampicillin, cefotaxime and methicillin--effected the greatest bactericidal activity and induced the most extensive morphological changes, which included the formation of membranous lesions through which cytoplasmic contents were lost. In terms of ultrastructural damage and loss of viability, the inhibitors of protein and DNA synthesis were less effective than the antibiotics that acted on the microbial cell wall. Erythromycin- and rifampicin-treated cells possessed irregular membranes and were partially or fully lysed, whereas ciprofloxacin induced abnormally elongated organisms with intermittently lysed and detached inner membranes. These results illustrated the ability of antibiotics of putative clinical value, with diverse modes of action, to affect the ultrastructural cytology as well as the viability of L. pneumophila in vitro.

4-Quinolones↗
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↗
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↗
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↗
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↗
PubMed1991

Comparative efficacies of soft contact lens disinfectant solutions against microbial films in lens cases.

Biofilms of Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus epidermidis, Streptococcus pyogenes, and Candida albicans, established in the wells of a polyethylene contact lens case, retained viability to certain soft contact lens disinfectant solutions after exposure for the manufacturer's minimum recommended disinfection times. The relative order of resistance of bacterial biofilms was as follows: S marcescens was greater than P aeruginosa, which was greater than S epidermidis, which was greater than S pyogenes. Air drying of biofilms for 10 hours increased the efficacy of the disinfectant solutions, but drying was not enough to decrease the incidence of recovery to 0% for all solutions. Hydrogen peroxide was more effective against biofilms than disinfectant solutions formulated with chlorhexidine gluconate or polyquaternium-1 or polyaminopropyl biguanide. We recommend that determination of efficacy of contact lens disinfectant solutions should include challenges against biofilms.

Bacteria↗
PubMed1992

Circulatory adaptation to the increased metabolism in the skin at the site of the tuberculin reaction.

The sequence of changes at the site of a positive tuberculin test response were studied in 19 healthy young adults who had been immunised with BCG in childhood. The development of erythema preceded that of induration and both were most intense at 48-72 h. The strongest reactions showed higher laser Doppler (LD) flux at the periphery than at the center (central relative slowing). All showed a substantial reduction in steady-state (ss) tcpO2 from 24 h onwards and the oxygen consumption rate (mlO2.kg-1.min-1), calculated from the rate of fall in tcpO2 during temporary cuff occlusion of arterial input, was raised (greater than two-fold) throughout the period of study (to 96 h). The density of lymphocytes and macrophages in the inflammatory infiltrate in the dermis was related to the fall in tcpO2.ss and to the extent of thickening of the dermis. These experiments showed that the previously healthy dermal microcirculation can adapt to temporary increase in metabolic demands of leucocytes emigrated from the circulation into the tissue: in intense delayed hypersensitivity (DHS) reactions there is considerable hypoxia and respiratory debt, but maintenance of viability in the short-term. It is likely that similar adaptations occur in the period of establishment of microbial infection.

Adaptation, Physiological↗
PubMed1987

[Role of the lipid peroxidation system of Escherichia coli cells in maintaining their viability in air].

The study of 6 E. coli strains differing in their capacity for survival in the air has revealed that the physicochemical characteristics of lipids in microbial cells, such as antioxidizing activity, the concentration of peroxidation products, the content of lipids and their capacity for oxidation, are interrelated, which confirms the existence of the system regulating the peroxidation of lipids in prokaryotic cells, similar to the system regulating lipid peroxidation in eukaryotic cells. The capacity of cells for survival in the air has been shown to depend on the physicochemical state of lipids in cellular membranes.

Air Microbiology↗
PubMed1969

Survival of T3 coliphage in varied extracellular environments. I. Viability of the coliphage during storage and in aerosols.

The objective of this study was to determine the feasibility of using airborne T3 coliphage as a viral tracer in microbial aerosols. Although T3 coliphage was relatively stable when stored either at temperatures ranging from 21 to 37 C or in the frozen state at -20 C, there was a 2-log loss in infectivity when stored for 72 days at 4 C. Either agitation of stored coliphage suspensions held at 31 C or wide fluctuations in storage temperature produced an increased loss of infectivity. In the airborne state, freshly prepared coliphage and stored coliphage behaved similarly, with survival diminishing as the relative humidity (RH) was lowered. The greatest loss occurred during the first five min following aerosolization. The results showed that only under certain conditions of temperature and relative humidity can T3 coliphage be used as a satisfactory aerosol tracer.

Aerosols↗