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Bacterial Viability (bacterial + viability)
Selected AbstractsRole of viability of probiotic strains in their persistence in the gut and in mucosal immune stimulationJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2004C. Maldonado Galdeano Abstract Aims:, To determine how probiotic bacteria contact with intestinal epithelial and immune cells and the conditions to induce a good mucosal immune stimulation. Methods and Results:,Lactobacillus casei was studied by transmission electron microscopy (TEM) to determine its interaction with the gut. We compared the influence of viable and nonviable lactic acid bacteria on the intestinal mucosal immune system (IMIS) and their persistence in the gut of mice. TEM showed whole Lact. casei adhered to the villi; the bacterial antigen was found in the cytoplasm of the enterocytes. Viable bacteria stimulated the IMIS to a greater extent than nonviable bacteria with the exception of Lact. delbrueckii subsp. bulgaricus. For all the strains assayed at 72 h no antigenic particles were found in the intestine. Conclusion:, Antigenic particles but not the whole bacteria can enter to epithelial cells and contact with the immune cells. Bacterial viability is a condition for a better stimulation of the IMIS. Significance and Impact of the Study:, We demonstrated that only antigenic particle interact with the immune cells and their fast clearance from the gut agrees with those described for the particulate antigens. The regular consumption of probiotics should not adversely affect the host. [source] Effect of pulsed ultrasound in combination with gentamicin on bacterial viability in biofilms on bone cements in vivoJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2005G.T. Ensing Abstract Aims:, The aim of this study is to investigate whether pulsed ultrasound (US) in combination with gentamicin yields a decreased viability of bacteria in biofilms on bone cements in vivo. Methods and Results:, Bacterial survival on bone cement in the presence and absence of ultrasound was compared in a rabbit model. Two bone cement samples with an Escherichia coli ATCC 10798 biofilm were implanted in a total of nine rabbits. In two groups bone cement discs loaded with gentamicin, freshly prepared and aged were used, and in one group unloaded bone cement discs in combination with systemically administered gentamicin. Pulsed ultrasound with a frequency of 28·48 kHz and a maximum acoustic intensity of 500 mW cm,2 was applied continuously from 24 h till 72 h postsurgery on one of the two implanted discs. After euthanization and removal of the bacteria from the discs, the number of viable bacteria were quantified and skin samples were analysed for histopathological examination. Application of ultrasound, combined with gentamicin, reduced the viability of the biofilms in all three groups varying between 58 and 69% compared with the negative control. Histopathological examinations showed no skin lesions. Conclusions:, Ultrasound resulted in a tendency of improved efficacy of gentamicin, either applied locally or systemically. Usage of ultrasound in this model proved to be safe. Significance and Impact of the Study:, This study implies that ultrasound could improve the prevention of infection immediately after surgery, especially because the biomaterials, gentamicin and ultrasound used in this model are all in clinical usage, but not yet combined in clinical practice. [source] Removal of Cadmium and Lead from Aqueous Solution by,Enterococcus faecium,StrainsJOURNAL OF FOOD SCIENCE, Issue 1 2010A. Topcu ABSTRACT:, Foods may be contaminated with heavy metals, which, even in small quantities, possess detrimental effects on human health. The aim of the present study was to investigate the uptake of cadmium or lead from an aqueous medium frequently found in foods, by 2,Enterococcus faecium,strains (E. faecium,EF031 and,E. faecium,M74). Also, the effects of the bacterial viability, incubation (contact) time, and pH on the binding capacities and binding stability were assessed. The results showed that both of the strains efficiently removed cadmium and lead. While EF031 removed 77.3% to 98.1% of cadmium and 66.9% to 98.9% of lead, M74 removed 53.5% to 91% of cadmium and 42.9% to 93.1% of lead throughout a 48 h incubation period at pH 5. It was found that, at 1 h, EF031 and M74 strains removed cadmium and lead, which was more than 60% of total removed cadmium and lead throughout the whole incubation period of 48 h. It suggests that the uptake of cadmium and lead by EF031 and M74 strains is a rapid process. The binding of both heavy metals increased with increasing pH of an aqueous medium and was the highest at pH 5. Also, the complexes formed between both heavy metals and bacterial cells were found to be stable. These findings indicate that,E. faecium,strains used in the study are able to bind the 2 heavy metals and may be used in the production of fermented functional foods, which will be healthy via its detoxification properties. [source] Unsuitable distinction between viable and dead Staphylococcus aureus and Staphylococcus epidermidis by ethidium bromide monoazideLETTERS IN APPLIED MICROBIOLOGY, Issue 5 2009H. Kobayashi Abstract Aims:, The DNA-intercalating dye ethidium bromide monoazide (EMA) has recently been used as a DNA binding agent to differentiate viable and dead bacterial cells by selectively penetrating through the damaged membrane of dead cells and blocking the DNA amplification during the polymerase chain reaction (PCR). We optimized and tested the assay in vitro using Staphylococcus aureus and Staphylococcus epidermidis cultures to distinguish viable from dead bacteria, with the goal of reducing false positive PCR results. Methods and Results:, Viable and heat-inactivated bacteria were treated with EMA or left untreated before DNA extraction. A real-time PCR assay for the detection of the tuf gene in each DNA extract was used. Our results indicated that EMA influenced viable bacteria as well as dead bacteria, and the effect of EMA depended on the EMA concentration and bacterial number. Conclusions:, EMA is not a suitable indicator of bacterial viability, at least with respect to Staphylococcus species. Significance and Impact of the Study:, Determining the viability of pathogens has a major impact on interpreting the results of molecular tests for bacteria and subsequent clinical management of patients. To this end, several methods are being evaluated. One of these methods , intercalating DNA of dead bacteria by EMA , looked very promising, but our study found it unsatisfactory for S. aureus and coagulase-negative Staphylococci. [source] Polar bacterial invasion and translocation of Streptococcus suis across the blood-cerebrospinal fluid barrier in vitroCELLULAR MICROBIOLOGY, Issue 2 2009Tobias Tenenbaum Summary Previous experimental studies in a standard Transwell culture system have shown Streptococcus suis ability to compromise barrier function of porcine choroid plexus epithelial cells (PCPEC). The development of an ,inverted' Transwell filter system of PCPEC enables us now for the first time to investigate bacterial invasion and translocation from the physiologically relevant basolateral (blood) to the apical (cerobrospinal fluid) side. Most importantly, we observed specific invasion and translocation of S. suis across the PCPEC exclusively from the basolateral side. During this process, bacterial viability and the presence of a capsule as well as cytoskeletal regulation of PCPEC seemed to play an important role. No loss of barrier function was observed. Bacterial translocation could be significantly inhibited by the phosphatidylinositol 3-kinase inhibitor LY294002, but not by its inactive analogue Ly303511 or dexamethasone. Apotome imaging as well as electron microscopy revealed intracellular bacteria often in cell vacuoles. Thus, possibly regulated by the presence of a capsule, S. suis induces signals that depend on the lipid kinase phosphatidylinositol 3-kinase pathway, which paves the way for cellular uptake during the bacterial transcellular translocation process. Taken together, our data underline the relevance of the blood,cerebrospinal fluid barrier as a gate for bacterial entry into the central nervous system. [source] | ||||||||||