Non-viable Microorganisms Research Articles

Antibacterial poly(D,L-lactic acid) coating of medical implants using a biodegradable drug delivery technology.

Biomaterial-associated bacterial infections present common and challenging complications with medical implants. The purpose of this study was to determine the antibacterial properties of a low molecular weight biodegradable poly(D,L-lactic acid) coating with integrated antibiotics gentamicin and teicoplanin. Coating of Kirschner-wires was carried out by a solvent casting technique under aseptic conditions with and without incorporated antibiotics. Release kinetics of gentamicin and teicoplanin were studied in phosphate-buffered saline. Initial bacterial adhesion of Staphylococcus epidermidis on coated and bare implants was determined by radiolabelling and counts of detached viable organisms. The incorporated antibiotics showed a continuous release over a period of at least 96 h with an initial peak of release in the first 6 h. Attachment of non-viable microorganisms, detected by radiolabelled bacteria, was increased significantly by the polymer coatings (P < 0.05). In contrast, the number of viable bacteria was reduced by the pure polymer (P < 0.01) and further by the polymer-antibiotic combinations (P < 0.05). Poly(D,L-lactic acid) coating of implants could offer new perspectives in preventing biomaterial-associated infections. Combinations with other drugs to formulate custom-tailored implant surfaces are feasible.

Methods for quantitative assessment of airborne levels of noninfectious microorganisms in highly contaminated work environments.

Exposure to high airborne levels of noninfectious microorganisms is recognized as a cause of respiratory symptoms and disease among workers handling biological materials, such as farmers, sawmill workers, and workers handling municipal waste and fuel chips. Risk assessment is difficult because occupational exposure limits for noninfectious microorganisms have not been established. Many different methods are used for the measurement of airborne microorganisms, which are based on impaction, impingement, or filtration. Samples can be analyzed by methods that are culture-based or nonculture-based and that may estimate different microbial entities: culturable microorganisms by culture-based methods, microbial cells by microscopic methods, and microbial constituents and products by chemical, biochemical and immunochemical methods. Sources of errors and validation studies of these methods are reviewed and methods are evaluated for exposure assessment in epidemiological studies and for future compliance testing. At present it is not clear which microbial bioaerosol components should be assessed. Culture-based methods are probably not satisfactory because nonviable microorganisms and microbial constituents and products also may cause health effects. Culture-based methods are poor surrogates for nonculture-based methods and have poor precision. However, identification of microorganisms is most readily performed by culture-based methods. Filter sampling is preferred for personal exposure measurements because filters can be analyzed by a variety of nonculture-based methods, and filter sampling may be adapted to recently adopted criteria for health-related size fractions.

Detection of pathogenic and spoilage micro-organisms in food with the polymerase chain reaction

Traditional biochemical and immunochemical methods for the detection of micro-organisms in food have been supplemented by a number of DNA-based methods during the last decade. Besides the development of direct hybridization techniques, emphasis has been laid onin vitroamplification methods.In vitromethods such as the self-sustained sequence replication (3SR) or the nucleic acid sequence based amplification (NASBA), the Q-beta replicase amplification and the ligase chain reaction (LCR) have had, until now, only limited practical relevance for food monitoring and control. The most developedin vitroamplification method is the polymerase chain reaction (PCR) that allows rapid and selective identification of micro-organisms. Because PCR is increasingly raising interest as a detection method in food hygiene and control, an overview of PCR-systems for the detection of bacteria and viruses in food is provided with this paper. Although the PCR method has advantages (particular specificity, sensitivity) it also has limitations, one of which is its inability to allow differentiation between viable and non-viable micro-organisms. Furthermore, the inhibition of PCR by food-derived inhibitors can result in false negative results. Possible reasons for PCR inhibition and ways to differentiate between viable and dead micro-organisms are discussed in this review.

Methods for Quantitative Assessment of Airborne Levels of Noninfectious Microorganisms in Highly Contaminated Work Environments

Exposure to high airborne levels of noninfectious microorganisms is recognized as a cause of respiratory symptoms and disease among workers handling biological materials, such as farmers, sawmill workers, and workers handling municipal waste and fuel chips. Risk assessment is difficult because occupational exposure limits for noninfectious microorganisms have not been established. Many different methods are used for the measurement of airborne microorganisms, which are based on impaction, impingement, or filtration. Samples can be analyzed by methods that are culture-based or nonculture-based and that may estimate different microbial entities: culturable microorganisms by culture-based methods, microbial cells by microscopic methods, and microbial constituents and products by chemical, biochemical and immunochemical methods. Sources of errors and validation studies of these methods are reviewed and methods are evaluated for exposure assessment in epidemiological studies and for future compliance testing. At present it is not clear which microbial bioaerosol components should be assessed. Culture-based methods are probably not satisfactory because nonviable microorganisms and microbial constituents and products also may cause health effects. Culture-based methods are poor surrogates for nonculture-based methods and have poor precision. However, identification of microorganisms is most readily performed by culture-based methods. Filter sampling is preferred for personal exposure measurements because filters can be analyzed by a variety of nonculture-based methods, and filter sampling may be adapted to recently adopted criteria for health-related size fractions.

Enzyme-linked immunosorbent assay for the detection of airborne microorganisms used in biotechnology

Many working environments contain viable and non-viable airborne microorganisms which may cause adverse health effects. Current assay methods rely on culturing techniques which only detect viable microorganisms and so result in underestimates of total concentrations of airborne microorganisms. This study investigated the use of a single antibody sandwich enzyme-linked immunosorbent assay (ELISA) for rapid, specific detection and enumeration of airborne microorganisms. ELISAs were developed for three microorganisms commonly used in the biotechnology industry ( Escherichia coli, Bacillus subtilis and Saccharomyces cerevisiae). These microorganisms were aerosolised and collected with an IOM personal sampler and a glass cyclone sampler. The resultant samples were assayed using the ELISAs. Results were compared to traditional culturing methods and light microscopy. The results indicated that ELISA provides a reliable, relatively rapid, specific and quantitative method for the detection of airborne microorganisms independent of their metabolic state.

Occurrence and origin of carbohydrates in peat samples from a red mangrove environment as reflected by abundances of neutral monosaccharides

Acid hydrolysates of fractionated red mangrove peat samples and handpicked roots and rootlets of Rhizophora mangle (red mangrove) from Jewfish Key in the Florida Everglades were analysed for neutral monosaccharides. In the peat samples two major sources of carbohydrates could be determined: 1. (1) vascular plant carbohydrates derived from Rhizophora mangle and 2. (2) microbially derived carbohydrates. Significant correlations exist between the relative contributions of most neutral monosaccharides and the total carbohydrate concentration. The fine-grained peat fractions yielded low total neutral monosaccharides whose distributions indicate contributions of microbial carbohydrates. The coarse-grained peat samples yielded high total neutral monosaccharides with distributions indicating major contributions of vascular plant carbohydrates. It is estimated that a substantial part of the sugars analysed in the finegrained samples originates from microorganisms ([cyano] bacteria, algae).The absence of a trend in total neutral monosaccharide concentrations with depth suggests that microbial degradation is limited to the upper levels of the peat and that the microbial sugars determined at lower peat levels are derived from nonviable or dormant microorganisms. Results from factor analysis may suggest differences in microbial populations in the various peat samples.

The nuclepore filter method: A technique for enumeration of viable and nonviable airborne microorganisms

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