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Viable Bacteria (viable + bacteria)
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] Characterization of susceptibility and carrier status of burbot, Lota lota (L.), to IHNV, IPNV, Flavobacterium psychrophilum, Aeromonas salmonicida and Renibacterium salmoninarumJOURNAL OF FISH DISEASES, Issue 7 2010M P Polinski Abstract In this study, susceptibility and potential carrier status of burbot, Lota lota, were assessed for five important fish pathogens. Burbot demonstrated susceptibility and elevated mortality following challenge with infectious haematopoietic necrosis virus (IHNV) by immersion and to Aeromonas salmonicida by intraperitoneal (i.p.) injection. IHNV persisted in fish for at least 28 days, whereas A. salmonicida was not re-isolated beyond 17 days post-challenge. In contrast, burbot appeared refractory to Flavobacterium psychrophilum following intramuscular (i.m.) injection and to infectious pancreatic necrosis virus (IPNV) by immersion. However, i.p injection of IPNV resulted in re-isolation of virus from fish for the duration of the 28 day challenge. Renibacterium salmoninarum appeared to induce an asymptomatic carrier state in burbot following i.p. injection, but overt manifestation of disease was not apparent. Viable bacteria persisted in fish for at least 41 days, and bacterial DNA isolated by diagnostic polymerase chain reaction was detected from burbot kidney tissue 90 days after initial exposure. This study is the first to investigate susceptibility of burbot to selected fish pathogens, and this information will aid in efforts to culture and manage this species. [source] Vectorization of Harungana madagascariensis Lam. ex Poir. (Hypericaceae) ethanolic leaf extract by using PLG-nanoparticles: antibacterial activity assessmentDRUG DEVELOPMENT RESEARCH, Issue 1 2005B. Moulari Abstract This study was undertaken to compare the in vitro and ex vivo antibacterial activity of an ethanolic Harungana madagascariensis leaf extract (HLE) incorporated into poly (D,L -lactide-co,glycolide) nanoparticles (HLE -PLG-NP). Two concentrations of HLE (500 and 1,000,µg/mL) for the in vitro study and one concentration (500 µg/mL) for the ex vivo study were compared using two gram-positive bacterial strains (Micrococcus luteus and Staphylococcus epidermidis), and one gram-negative bacterial strain (Moraxella sp.). The ex vivo antibacterial activity was evaluated on S. epidermidis CIP 55109 (SE) using an artificial contamination method. SE was inoculated for 12 h onto human skin fragment surfaces treated for 5,min either with HLE loaded, unloaded PLG-NP, or HLE solution. In vitro, the two preparations inhibited completely the growth of all bacterial strains at 1,000,µg/mL. However, the HLE -PLG-NP had a significant antibacterial activity against SE (18.4±1.8,0.4±0.2 CFU/mL, P<0.05), and a marked antibacterial effect against M. luteus (ML) and Moraxella sp. (Msp) compared to HLE solution at 500 µg/mL. Ex vivo, HLE -PLG-NP at 500,µg/mL reduced viable bacteria (6.3,4.8 log10), compared to the HLE solution (6.3,5.5 log10) after 4 h artificial contamination (P<0.05). A thin layer chromatography study of both HLE solution and HLE -PLG-NP showed that among the seven components found on the chromatogram of the HLE solution, only two were present on the nanoparticles, one including a flavonoid heteroside fraction responsible for the antibacterial properties. The incorporation of the HLE into a colloidal carrier improved antibacterial performance. Drug Dev. Res. 65:26,33, 2005. © 2005 Wiley-Liss, Inc. [source] The surface-associated elongation factor Tu is concealed for antibody binding on viable pneumococci and meningococciFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 2 2008Jan Kolberg Abstract Proteome analyses revealed that elongation factor-Tu (EF-Tu) is associated with cytoplasmic membranes of Gram-positive bacteria and outer membranes of Gram-negative bacteria. It is still debatable whether EF-Tu is located on the external side or the internal side of the membranes. Here, we have generated two new monoclonal antibodies (mAbs) and polyclonal rabbit antibodies against pneumococcal EF-Tu. These antibodies were used to investigate the amount of surface-exposed EF-Tu on viable bacteria using a flow cytometric analysis. The control antibodies recognizing the pneumococcal surface protein A and phosphorylcholine showed a significant binding to viable pneumococci. In contrast, anti-EF-Tu antibodies did not recognize pneumococcal EF-Tu. However, heat killing of pneumococci lacking capsular polysaccharides resulted in specific antibody binding to EF-Tu and, moreover, increased the exposure of recognized phosphorylcholine epitopes. Similarly, our EF-Tu-specific antibodies did not recognize EF-Tu of viable Neisseria meningitidis. However, pretreatment of meningococci with ethanol resulted in specific antibody binding to EF-Tu on outer membranes. Importantly, these treatments did not destroy the membrane integrity as analysed with control mAbs directed against cytoplasmic proteins. In conclusion, our flow cytrometric assays emphasize the importance of using viable bacteria and not heat-killed or ethanol-treated bacteria for surface-localization experiments of proteins, because these treatments modulate the cytoplasmic and outer membranes of bacteria and the binding results may not reflect the situation under physiological conditions. [source] Octenidine in root canal and dentine disinfection ex vivoINTERNATIONAL ENDODONTIC JOURNAL, Issue 11 2007L. Tandjung Abstract Aim, The aim of the present study was to investigate the antimicrobial activity of octenidine on Enterococcus faecalis ATCC 29212 in a dentine block model. Methodology, Fifty-six root segments of extracted human teeth were infected with E. faecalis for 4 weeks. Octenidine-phenoxyethanol gel (1 : 1) was applied for different timing: 1 min, 10 min, 7 days and in a different formula (1 : 3) for 10 min. Three samples were chosen for the group with placebo gel and for the group without infection (negative control). Dentine samples were collected, and the total count of bacteria and colony-forming units were determined. In addition, for controls and the 10 min group with 1 : 1 gel, the proportion of viable bacteria (PVB) was assessed. Results, Octenidine was particularly effective after incubation periods of 10 min and 7 days. The mean PVB decreased significantly from 57.2% to 5.7% after 10 min application. After 7 days, only one of 10 samples showed positive culture. Conclusion, The present study showed the effectiveness of octenidine against E. faecalis in dentine disinfection. Further laboratory and clinical studies are required. [source] Oligonucleotide microarrays for the detection and identification of viable beer spoilage bacteriaJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2008D.G. Weber Abstract Aims:, The design and evaluation of an oligonucleotide microarray in order to detect and identify viable bacterial species that play a significant role in beer spoilage. These belong to the species of the genera Lactobacillus, Megasphaera, Pediococcus and Pectinatus. Methods and Results:, Oligonucleotide probes specific to beer spoilage bacteria were designed. In order to detect viable bacteria, the probes were designed to target the intergenic spacer regions (ISR) between 16S and 23S rRNA. Prior to hybridization the ISR were amplified by combining reverse transcriptase and polymerase chain reactions using a designed consenus primer. The developed oligonucleotide microarrays allows the detection of viable beer spoilage bacteria. Conclusions:, This method allows the detection and discrimination of single bacterial species in a sample containing complex microbial community. Furthermore, microarrays using oligonucleotide probes targeting the ISR allow the distinction between viable bacteria with the potential to grow and non growing bacteria. Significance and Impact of the Study:, The results demonstrate the feasibility of oligonucleotide microarrays as a contamination control in food industry for the detection and identification of spoilage micro-organisms within a mixed population. [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] Internalization of bioluminescent Escherichia coli and Salmonella Montevideo in growing bean sproutsJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2003K. Warriner Abstract Aims: Investigate the interaction of bioluminescent Escherichia coli and Salmonella Montevideo with germinating mung bean sprouts. Methods and Results:E. coli or Salm. Montevideo introduced on mung beans became established both internally and externally on sprouts after the initial 24 h germinating period. In both cases the inoculated bacterium formed the predominant microflora on the sprouted beans throughout. From the bioluminescent profile of inoculated sprouting beans, bacterial growth was found to be in close proximity to the roots but not on the hypocotyls. Clumps (biofilms) of cells with low viability were observed within the grooves between epidermal cells on hypocotyls. Treatment with 20 000 ppm sodium hypochlorite removed the majority of bacteria from the surface of hypocotyls although nonviable single cells were occasionally observed. However, viable bacteria were recovered from the apoplastic fluid, and extracts of surface-sterilized sprouts indicating that the internal bacterial populations had been protected. This was confirmed using in situ , -glucuronidase staining of surface-sterilized sprouts where cleaved enzyme substrate (by the action of internalized E. coli) was visualized within the plant vascular system. Conclusions:E. coli or Salmonella present on seeds become internalized within the subsequent sprouts and cannot be removed by postharvest biocidal washing. Significance and Impact of the Study: Mung bean production should be carefully controlled to prevent contamination occurring in order to minimize the health risk associated with raw bean sprouts. [source] Determining the spatial distribution of viable and nonviable bacteria in hydrated microcosm dental plaques by viability profilingJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2002C.K. Hope Aims: The aim of this study was to use confocal laser scanning microscopy (CLSM) to examine the spatial distribution of both viable and nonviable bacteria within microcosm dental plaques grown in vitro. Previous in vivo studies have reported upon the distribution of viable bacteria only. Methods and Results: Oral biofilms were grown on hydroxyapatite (HA) discs in a constant-depth film fermenter (CDFF) from a saliva inoculum. The biofilms were stained with the BacLightTM LIVE/DEAD system and examined by CLSM. Fluorescence intensity profiles through the depth of the biofilm showed an offset between the maximum viable intensity and the maximum nonviable intensity. Topographical differences between the surface properties of the viable and nonviable biofilm virtual surfaces were also measured. Conclusions: The profile of fluorescence intensity from viable and nonviable staining suggested that the upper layers of the biofilm contain proportionally more viable bacteria than the lower regions of the biofilm. Significance and Impact of Study: Viability profiling records the transition from predominantly viable to nonviable bacteria through biofilms suggesting that this technique may be of use for quantifying the effects of antimicrobial compounds upon biofilms. The distribution of viable bacteria was similar to that found in dental plaque in vivo suggesting that the CDFF produces in vitro biofilms which are comparable to their in vivo counterparts in terms of the spatial distribution of viable bacteria. [source] Synthesis, characterization, and thermal and antimicrobial studies of newly developed transition metal,polychelates derived from polymeric Schiff baseJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2009Nahid Nishat Abstract Monomeric Schiff base derived from salicylaldehyde and 1,3-diaminopropane was subjected to polycondensation reaction with formaldehyde and piperazine in basic medium. The resin was found to form polychelates readily with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) metal ions. The materials were characterized by elemental analysis, spectral studies (IR, 1H-NMR, 13C-NMR, and UV,visible), magnetic moment measurements, and thermal analysis. The electronic spectra and magnetic moment measurements of the synthesized polychelates confirmed the geometry of the central metal ion. Metal,resin bonds were registered in the IR spectra of the polychelates. The thermogravimetric analysis data indicated that the polychelates were more stable than the corresponding polymeric Schiff base. All the synthesized metal,polychelates showed excellent antibacterial activities against the selected bacteria. The antimicrobial activities were determined by using the shaking flask method, where 25 mg/mL concentrations of each compound were tested against 105 CFU/mL bacteria solutions. The number of viable bacteria was calculated by using the spread-plate method, where 100 ,L of the incubated antimicrobial agent in bacteria solutions were spread on agar plates, and the number of bacteria was counted after 24 h of incubation period at 37°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] In vitro markers for virulence in Yersinia ruckeriJOURNAL OF FISH DISEASES, Issue 3 2010E Tobback Abstract In this study, different traits that have been associated with bacterial virulence were studied in Yersinia ruckeri. Two isolates that had been shown to cause disease and mortality in experimentally infected rainbow trout were compared with five avirulent isolates. Both virulent isolates showed high adhesion to gill and intestinal mucus of rainbow trout, whereas the majority of non-virulent strains demonstrated significantly lower adhesion. A decrease in adherence capability following bacterial treatment with sodium metaperiodate and proteolytic enzymes suggested the involvement of carbohydrates and proteins. All strains were able to adhere to and invade chinook salmon embryo cell line (CHSE-214), fathead minnow epithelial cell line (FHM) and rainbow trout liver cell line (R1). One non-virulent strain was highly adhesive and invasive in the three cell lines, whereas the virulent strains showed moderate adhesive and invasive capacity. The internalization of several isolates was inhibited by colchicine and cytochalasin-D, suggesting that microtubules and microfilaments play a role. For all strains, intracellular survival assays showed a decrease of viable bacteria in the cells 6 h after inoculation, suggesting that Y. ruckeri is not able to multiply or survive inside cultured cells. Analysis of the susceptibility to the bactericidal effect of rainbow trout serum demonstrated that virulent Y. ruckeri strains were serum resistant, whereas non-virulent strains were generally serum sensitive. [source] Susceptibility of selected freshwater fish species to a UK Lactococcus garvieae isolateJOURNAL OF FISH DISEASES, Issue 10 2009M Algöet Abstract Gram-positive cocci recovered from diseased rainbow trout from a farm in England were characterized by different methods, including pulsed field gel electrophoresis, as virulent Lactococcus garvieae serogroup 2 (pulsotype A1). Groups of rainbow trout were kept at a range of temperatures and injected intraperitoneally (i.p.) with one of the UK isolates, L. garvieae 00021. The 18 °C and 16 °C groups showed 67% and 28% mortality, respectively, by day 27 post-injection. Fish kept at 14 °C or lower were less susceptible (,3% mortality). Raising the temperature of all groups to 18 °C at day 27 post-injection did not result in recurrence of the disease, even though viable bacteria were recovered from all groups 42 days later. Grayling were highly susceptible, with 65% mortalities when challenged with 200 colony forming unit fish,1 by i.p. injection and 37% mortalities when exposed to effluent water from tanks containing affected rainbow trout. Other fish species tested, Atlantic salmon, brown trout and seven cyprinid species, were less susceptible. Viable L. garvieae was isolated from the internal organs of all species tested at the end of the trials, suggesting that they may pose a threat as possible carriers to susceptible farmed and wild fish. [source] Biotransformation of Isoflavone Glycosides by Bifidobacterium animalis in Soymilk Supplemented with Skim Milk PowderJOURNAL OF FOOD SCIENCE, Issue 8 2007T.T. Pham ABSTRACT:, Two probiotic strains, Bifidobacterium animalis A and B, were used for the biotransformation of isoflavone glycosides in soymilk prepared from soy protein isolate (SPI) supplemented with skim milk powder (SMP) (SSMP). Unsupplemented soymilk (USM) and reconstituted skim milk powder (RSMP) were used as controls. The numbers of viable microorganisms in these products were enumerated. Lactose and isoflavone contents were quantified using high-performance liquid chromatography (HPLC). Our results showed that there was significantly higher biotransformation of isoflavone glycosides to aglycones in SSMP than that in USM. The levels of biotransformation were 83.96% and 85.43% for B. animalis A and B, respectively, compared to 74.30% and 72.82% for the USM. In addition, lactose utilization by both strains in SSMP was also higher than that in RSMP. At 24 h, 21.16 mg/mL of lactose was utilized in SSMP by B. animalis A compared with that of 16.88 mg/mL in RSMP. Consequently, the pH of SSMP was lower (3.80) than RSMP (4.00). However, the number of viable bacteria in SSMP was slightly lower than that in RSMP but significantly higher than that in USM. It appears that SMP enhanced the biotransformation of isoflavone glycosides to aglycones and SPI increased the lactose utilization by B. animalis A and B. [source] Development of Shelf-stable Intermediate-moisture Meat Products Using Active Edible ChitosanCoating and IrradiationJOURNAL OF FOOD SCIENCE, Issue 7 2005M. Shobita Rao ABSTRACT Shelf-stable intermediate-moisture (IM) meat products were developed using a combination of hurdles such as reduced aw, active edible coating of chitosan, and irradiation. Chitosan prepared from chitin had a viscosity of 16 c P, molecular weight of 17.54 kDa, and a degree of deacetylation (DD) of 74%. The nitrogen content of the chitosan was estimated to be 7.56%. The antioxidant activity of chitosan increased upon irradiation without significantly affecting its antimicrobial property. The effect of irradiated chitosan coating in terms of its antimicrobial and antioxidant properties in IM meat products immediately after irradiation and during storage was assessed. The aw of meat products such as mutton sheek kababs and streaky bacon was first reduced to 0.85 ± 0.02. The products were then coated with chitosan and irradiated (4 kGy). No viable bacteria or fungi were detected in chitosan-coated, irradiated products. In contrast, IM meat products that were not subjected to gamma radiation showed visible fungal growth within 2 wk. The chitosan-coated products showed lower thiobarbituric acid-reactive substances (TBARS) than the noncoated samples for up to 4 wk of storage at ambient temperature. The studies thus clearly indicated the potential use of chitosan coating for the preparation of safe and stable meat products. [source] Adherence of Streptococcus mutans to various restorative materials in a continuous flow systemJOURNAL OF ORAL REHABILITATION, Issue 3 2004S. Eick summary, A continuous flow system was developed to evaluate the adhesion of Streptococcus mutans ATCC 25175 to filling materials (Ariston, Tetric, Dyract, Compoglass, Vitremer, Aqua Ionofil, Ketac Fil, amalgam, Galloy and ceramics as controls). Streptococcus mutans was added to saliva-coated test specimens, and a nutrient broth permanently supplied over a time period of 48 h and then the weight of plaque, the number and viability of the bacteria adhering to the materials were determined. The weights of artificial plaque on all filling materials tested were higher than those on ceramics, the highest values were measured on the glass,ionomers. The amount of plaque correlates with the surface roughness, whereas there was no correlation of the surface roughness with the number of colony-forming units (CFU) of S. mutans. The CFU of adhering S. mutans also depends on the viability of the bacteria. The plaque on Ketac Fil contained a high number of viable bacteria. The fluorides of glass,ionomers do not efficiently prevent the attachment and the viability of S. mutans. [source] Clinical efficacy of intravenous administration of marbofloxacin in a Staphylococcus aureus infection in tissue cages in poniesJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 6 2006M. VOERMANS Tissue cages (TC), implanted subcutaneously in the neck in eight ponies, were inoculated with Staphylococcus aureus (S. aureus) to determine the clinical efficacy of marbofloxacin in the treatment of this infection. From 21 h after inoculation, marbofloxacin (6 mg/kg) was administered intravenously (i.v.) once daily for 7 days. Samples of the tissue cage fluid (TCF) were taken to determine marbofloxacin concentrations (days 1, 3 and 7), using high-pressure liquid chromatography, and numbers of viable bacteria [colony forming units (CFU)] (days 1, 3, 7, 14 and 21). Statistical analysis was used to compare CFU before and after treatment. Clinical signs and CFU were used to evaluate the efficacy of treatment. Although, there was a slight decrease in CFU in all TC initially, the infection was not eliminated by marbofloxacin treatment in any of the ponies and abscesses formed. As the MIC (0.25 ,g/mL) did not change during treatment and the concentration of marbofloxacin during treatment (mean concentration in TCF was 0.89 ,g/mL on day 1, 0.80 ,g/mL on day 3 and 2.77 ,g/mL on day 7) was above MIC, we consider that the treatment failure might be attributable to the formation of a biofilm by S. aureus. Based on the present results, i.v. administration of marbofloxacin alone is not suitable for the elimination of S. aureus infections from secluded sites. [source] Efficacy of trimethoprim-sulfadoxine against Escherichia coli in a tissue cage model in calvesJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 6 2002C. Greko Tissue cages implanted subcutaneously in calves were infected with Escherichia coli. Twenty-four hours later, the calves were treated either with single doses of 2.5 + 12.5 or 5 + 25 mg/kg trimethoprim (TMP) + sulfadoxine (SDX) or with five doses of 7.5 + 37.5 mg/kg TMP + SDX at 12-h intervals. In addition, one cage in each of three calves in the highest dose group was infected 3 h after initiation of treatment. Untreated calves were kept as controls. Concentrations of TMP and SDX in plasma and tissue cage fluid (TCF) and counts of viable bacteria in TCF were determined. In the highest dose group, concentrations of TMP in TCF remained above the minimum inhibitory concentration of the test strain for 94,101 h and peak to minimum inhibitory concentration (MIC) ratio was close to 10. In spite of this, an effect of treatment was noted only in cages infected after initiation of treatment. In vitro studies and analysis of thymidine content in serum and TCF from calves suggest that levels of thymidine in TCF are high enough to antagonize the antibacterial effect of TMP. The results indicate that soft tissue infections in secluded infection sites of calves are refractory to treatment with TMP + SDX. [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] Influence of copper-alloying of austenitic stainless steel on multi-species biofilm developmentLETTERS IN APPLIED MICROBIOLOGY, Issue 2 2001J. Kielemoes Aims: To investigate the bactericidal influence of copper-alloying of stainless steel on microbial colonization. Methods and Results: Inhibition of bacterial adherence was investigated by monitoring (192 h) the development of a multi-species biofilm on Cu-alloyed (3·72 wt%) stainless steel in a natural surface water. During the first 120 h of exposure, lower numbers of viable bacteria in the water in contact with copper-containing steel relative to ordinary stainless steel were observed. Moreover, during the first 48 h of exposure, lower colony counts were found in the biofilm adhering to the Cu-alloyed steel. No lower colony or viable counts were found throughout the remainder of the experimental period. Conclusions: The presence of Cu in the steel matrix impedes the adhesion of micro-organisms during an initial period (48 h), while this bactericidal effect disappears after longer incubation periods. Significance and Impact of the Study: The application of Cu-alloyed stainless steels for bactericidal purposes should be restricted to regularly-cleaned surfaces. [source] Non-opsonic phagocytosis of homologous non-toxigenic and toxigenic Corynebacterium diphtheriae strains by human U-937 macrophagesMICROBIOLOGY AND IMMUNOLOGY, Issue 1 2010Cíntia Silva Dos Santos ABSTRACT As interactions between bacteria and macrophages dictate the outcome of most infectious diseases, analyses of molecular mechanisms of non-opsonic phagocytosis should lead to new approaches for the prevention of diphtheria and systemic Corynebacterium diphtheriae infections. The present study aimed to evaluate human macrophage,bacteria interactions in the absence of opsonin antibodies and the influence of the tox gene on this process. Homologous C. diphtheriae tox+ and tox, strains were evaluated for adhesion, entering and survival within U-937 human macrophages at different incubation periods. Higher numbers of viable bacteria associated with and internalized by macrophages were demonstrated for the tox+ strain. However, viable intracellular bacteria were detected at T-24 hr only for the tox, strain. Cytoskeletal inhibitors, cytochalasin E, genistein and colchicine, inhibited intracellular viability of both strains at different levels. Bacterial replication was evidenced at T-24 hr in supernatants of monolayers infected with the tox, strain. Host cell death and nuclear alterations were evidenced by the Trypan blue exclusion assay and DAPI fluorescence microscopy. ELISA of histone-associated DNA fragments allowed detection of apoptosis and necrosis induced by tox+ and tox, strains at T-1 hr and T-3 hr. In conclusion, human macrophages in the absence of opsonins may not be promptly effective at killing diphtheria bacilli. The presence of the tox gene influences the susceptibility of C. diphtheriae to human macrophages and the outcome of non-opsonic phagocytosis. C. diphtheriae strains exhibit strategies to survive within macrophages and to exert apoptosis and necrosis in human phagocytic cells, independent of the tox gene. [source] Perpetuation of subgingival biofilms in an in vitro modelMOLECULAR ORAL MICROBIOLOGY, Issue 1 2010L.M. Shaddox Summary This study evaluated the reproducibility of in-vitro -grown biofilms, initiated with subgingival plaque from patients with periodontal disease, and continued through several cycles by re-inoculating new biofilms from previously grown biofilms. Subgingival plaque samples from bleeding pockets along with saliva samples were collected from three patients with chronic periodontitis and perpetuated through seven cycles. Calcium hydroxyapatite disks were coated with sterilized saliva inoculated with dispersed subgingival plaque. The biofilms were grown anaerobically at 37°C for 10 days, and at specific intervals total viable bacteria were enumerated and the species present were analysed by DNA,DNA checkerboard hybridization. All cycles of biofilm growth occurred at similar rates and reached steady-state at day 7. No statistically or microbially significant differences were found for viable counts or species present, at the same period of maturation, among the different cycles. This study demonstrated that growth of certain target subgingival periodontal species in this biofilm model was reproducible and could be perpetuated in vitro through several cycles. The model could be useful in future studies to characterize different periodontopathogenic properties and biofilm interactions, especially in recolonization studies. [source] Selective induction of human beta-defensin mRNAs by Actinobacillus actinomycetemcomitans in primary and immortalized oral epithelial cellsMOLECULAR ORAL MICROBIOLOGY, Issue 6 2003E. C. Feucht Human beta-defensin-2, and -3 (hBD-2, -3) are small inducible antimicrobial peptides involved in host defense. Actinobacillus actinomycetemcomitans, a gram-negative facultative anaerobe, is frequently associated with oral disease in humans. A. actinomycetemcomitans, strain JP2, was examined for its ability to modulate hBD-2 and -3 gene expression in normal human oral epithelial cells (NHOECs) and in OKF6/Tert cells, an immortalized cell line derived from human oral epithelial cells. Stimulation of both cell types by live bacteria, at a minimal bacteria/cell ratio of 500 : 1, resulted in increased hBD-3 gene expression. This was not evinced for hBD-2 in either cell type with live bacteria, even at bacteria/cell ratios exceeding 500 : 1. The increased hBD-3 gene expression was dependent upon viable bacteria, and not their lipopolysaccharides (LPS), since heat-killed A. actinomycetemcomitans did not induce hBD-3 transcript expression. The overall similarity between results obtained in OKF6/Tert cells and NHOECs suggest that the OKF6/Tert cell line may be a useful tool in the study of beta-defensin expression in oral epithelium. [source] Temporal patterns and quantification of excretion of Mycobacterium avium subsp paratuberculosis in sheep with Johne's diseaseAUSTRALIAN VETERINARY JOURNAL, Issue 1 2000RJ WHITTINGTON Objectives To determine the frequency of excretion of Mycobacterium avium subsp paratuberculosis in Merino sheep with Johne's disease and to quantify excretion in a group of Merino sheep. Design A pen and laboratory experiment Procedure Seven sheep selected from an affected flock on the basis of acid-fast bacilli in the sheep's faeces were housed and total daily faecal output was collected, weighed and subjected to culture for M avium subsp paratuberculosis. An end-point titration method was used to enumerate viable M avium subsp paratuberculosis in a 15 day pooled sample from five sheep that had acid-fast bacilli in their faeces while housed. Results Four sheep with subclinical multibacillary Johne's disease excreted M avium subsp paratuberculosis each day for 11 days of cultural observation. A further three sheep were intermittent excreters but lacked other evidence of infection with M avium subsp paratuberculosis. The average number of viable bacteria excreted was 1.09 × 108 per gram of faeces while total daily excretion was 8.36 × 1010 viable M avium subsp paratuberculosis per sheep. Examination of faecal smears stained with Ziehl Neelsen was an unreliable means of assessing daily excretion in individual animals except in those with severe lesions. Conclusion Excretion of M avium subsp paratuberculosis in Merino sheep with multibacillary Johne's disease occurred daily, proving that environmental contamination can be continuous on farms with endemic ovine Johne's disease. Faecal culture is a useful method for detecting infection as it does not appear to be affected by the timing of collection of a sample from sheep with multibacillary disease however, to maximise the sensitivity of disease surveillance using faecal culture, sampling rates should be adjusted to take account of the proportions of multibacillary and paucibacillary cases. [source] Induction of type I interferons by bacteriaCELLULAR MICROBIOLOGY, Issue 7 2010Kathryn M. Monroe Summary Type I interferons (IFNs) are secreted cytokines that orchestrate diverse immune responses to infection. Although typically considered to be most important in the response to viruses, type I IFNs are also induced by most, if not all, bacterial pathogens. Although diverse mechanisms have been described, bacterial induction of type I IFNs occurs upon stimulation of two main pathways: (i) Toll-like receptor (TLR) recognition of bacterial molecules such as lipopolysaccharide (LPS); (ii) TLR-independent recognition of molecules delivered to the host cell cytosol. Cytosolic responses can be activated by two general mechanisms. First, viable bacteria can secrete stimulatory ligands into the cytosol via specialized bacterial secretion systems. Second, ligands can be released from bacteria that lyse or are degraded. The bacterial ligands that induce the cytosolic pathways remain uncertain in many cases, but appear to include various nucleic acids. In this review, we discuss recent advances in our understanding of how bacteria induce type I interferons and the roles type I IFNs play in host immunity. [source] Initiation of alcoholic fatty liver and hepatic inflammation with a specific recall immune response in alcohol-consuming C57Bl/6 miceCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 1 2001I. I. Slukvin Whether immunological responses are involved in initiation and progression of alcoholic liver disease is unclear. We describe a mouse model of alcoholic liver injury characterized by steatosis and hepatic inflammation initiated by a recall immune response. Mice immune to Listeria monocytogenes fed a liquid diet containing ethanol and challenged with viable bacteria developed steatosis within 24 h and, at a later time, elevated serum alanine aminotransferase levels, indicating more liver damage in this group. Listeria antigen also induced steatosis and increased serum alanine aminotransferase levels in immune ethanol-consuming mice. The production of tumour necrosis factor by a recall immune response in this model is a major, but not the only, component in initiation of alcoholic liver disease. [source] | |||||||||||||