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Different Bacterial Species (different + bacterial_species)
Selected AbstractsDetection of bacterial DNA by PCR and reverse hybridization in the 16S rRNA gene with particular reference to neonatal septicemiaACTA PAEDIATRICA, Issue 2 2001S Shang Aim: The clinical diagnosis of sepsis is difficult, particularly in neonates. It is necessary to develop a rapid and reliable method for detecting bacteria in blood and cerebrospinal fluid (CSF) Polymerase chain reaction (PCR) and reverse hybridization of the 16S rRNA gene would permit fast and sensitive determination of the presence of bacteria and differentiate gram-positive bacteria from gram-negative ones in clinical specimens. Methods: We developed a pair of primers according to the gene encoding 16SrRNA found in all bacteria. DNA fragments from different bacterial species and from clinical samples were detected with PCR, and with reverse hybridization using a universal bacterial probe, a gram-positive probe and a gram-negative probe. Results: A 371 bp DNA fragment was amplified from 20 different bacterial species. No signal was observed when human DNA and viruses were used as templates. The sensitivity could be improved to 10T -12 g. All 26 culture-positive clinical samples (22 blood samples and 4 CSF samples) were positive with PCR. The gram-negative and gram-positive probes hybridized to clinical samples and to known bacterial controls, as predicted by Gram's stain characteristics. Conclusions: Our results suggest that the method of PCR and reverse hybridization is rapid, sensitive and specific in detecting bacterial infections. This finding may be significant in the clinical diagnosis of sepsis in neonates. [source] Dynamics of bacterial cytoskeletal elementsCYTOSKELETON, Issue 11 2009Peter L. Graumann Abstract Bacterial cytoskeletal elements are involved in an astonishing spectrum of cellular functions, from cell shape determination to cell division, plasmid segregation, the positioning of membrane-associated proteins and membrane structures, and other aspects of bacterial physiology. Interestingly, these functions are not necessarily conserved, neither between different bacterial species nor between bacteria and eukaryotic cells. The flexibility of cytoskeletal elements in performing different tasks is amazing and emphasises their very early development during evolution. This review focuses on the dynamics of cytoskeletal elements from bacteria. Cell Motil. Cytoskeleton 2009. © 2009 Wiley-Liss, Inc. [source] The structure of a local population of phytopathogenic Pseudomonas brassicacearum from agricultural soil indicates development under purifying selection pressureENVIRONMENTAL MICROBIOLOGY, Issue 3 2001Johannes Sikorski Among the isolates of a bacterial community from a soil sample taken from an agricultural plot in northern Germany, a population consisting of 119 strains was obtained that was identified by 16S rDNA sequencing and genomic fingerprinting as belonging to the recently described species Pseudomonas brassicacearum. Analysis of the population structure by allozyme electrophoresis (11 loci) and random amplified polymorphic DNA,polymerase chain reaction (RAPD,PCR; four primers) showed higher resolution with the latter method. Both methods indicated the presence of three lineages, one of which dominated strongly. Stochastic tests derived from the neutral theory of evolution (including Slatkin's exact test, Watterson's homozygosity test and the Tajima test) indicated that the population had developed under strong purifying selection pressure. The presence of strains clearly divergent from the majority of the population can be explained by in situ evolution or by influx of strains as a result of migration or both. Phytopathogenicity of a P. brassicacearum strain determined with tomato plants reached the level obtained with the type strain of the known pathogen Pseudomonas corrugata. The results show that a selective sweep was identified in a local population. Previously, a local selective sweep had not been seen in several populations of different bacterial species from a variety of environmental habitats. [source] Autolytic phenotype of Lactococcus lactis strains isolated from traditional Tunisian dairy productsJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2002H. Ouzari Aims:,To evaluate the autolytic properties of Lactococcus lactis strains isolated from artisan Tunisian dairy products, their peptidoglycan hydrolase content and their activity spectrum. Methods and Results:,The autolytic phenotype of Lactococcus strains was evaluated under starvation conditions in potassium phosphate buffer. The results obtained highlighted a high degree of diversity among the strains analysed, allowing the identification of high and low autolytic Lactococcus lactis strains. Peptidoglycan hydrolase content was evaluated by renaturing SDS-PAGE using cells of Micrococcus lysodeikticus as a target for the enzymatic activity. A major activity band migrating at about 45 kDa was observed. The lytic activity, evaluated in the presence of different chemicals, was retained in 8% NaCl, 15 mmol l,1 CaCl2, and in a pH range between 5 and 9·5. The substrate specificity of peptidoglycan hydrolase from Lactococcus strains was evaluated in renaturing SDS-PAGE incorporating cells of different bacterial species. The major autolysin of Lactococcus lactis was active against cells of Lactococcus lactis subsp. lactis, Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus helveticus and Listeria monocytogenes. Conclusions:,Autolytic activity is widely distributed in Lactococcus lactis and the rate of autolysis is strain-dependent. The major peptidoglycan hydrolase showed a wide spectrum of activity against several lactic acid bacteria and bacterial species involved in food-related infection. Significance and Impact of the Study:,The autolytic phenotype of Lactococcus lactis strains isolated from Tunisian artisan dairy products has been determined, and the data obtained should allow the selection of strains of technological interest in the cheese-ripening process. [source] Detection of periodontal bacterial DNA in serum and synovial fluid in refractory rheumatoid arthritis patientsJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 12 2009Rita E. Martinez-Martinez Abstract Aim: To identify periodontal bacterial DNA (PBDNA) by PCR in subgingival dental plaque (SDP), serum and synovial fluid (SF) of rheumatoid arthritis (RA) with periodontal disease (PD) patients and to explore the possible PBDNA transport pathways from mouth to joints. Methods: This cross-sectional prolective study involved 19 subjects with RA and PD. Informed consent, health and dental questionnaires were obtained. SDP, SF and serum samples were obtained, and leucocytes were isolated from blood. DNA was extracted and PCR assays to detect main PD species were carried out. Cultures on agar plates and broth, from each sample, were performed. Results: Hundred percentage of patients showed PBDNA in SDP and SF and 83.5% in serum. Prevotella intermedia (89.4% and 73.6%) and Porphyromonas gingivalis (57.8% and 42.1%) were the species most frequently detected in SDP and SF, respectively. In SDP, 4.05 different bacterial species were found followed by 1.19 in serum and 2.26 in SF. Culture onto agar plates and broth did not show any bacterial growth, leucocytes were not positive to PBDNA by PCR. Conclusion: This study suggests that PBDNA could have a role on the RA aetiology. The possible pathway of transport of PBDNA from mouth to joints could be via the free form of DNA. [source] Antimicrobial resistance in the subgingival microflora in patients with adult periodontitisJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 2 2000A comparison between The Netherlands, Spain Abstract Background: The widespread use of antibiotics for prophylaxis and treatment of bacterial infections has lead to the emergence of resistant human pathogens. Great differences have been documented between European countries in the use of systemic antibiotics. In parallel, significant differences in levels of resistant pathogens have been documented. Aim: To investigate whether differences in antibiotic use influence the level of antimicrobial resistance of the subgingival microflora of untreated patients with adult periodontitis in The Netherlands and Spain. Method: Blood agar plates containing breakpoint concentrations of penicillin, amoxicillin, amoxicillin and clavunalate, metronidazole, erythromycin, azithromycin, clindamycin and tetracycline were used to determine the proportion of bacteria from the subgingival plaque that was resistant to these antibiotics. In the Spanish patients, statistically significant higher mean levels of resistance were found for penicillin, amoxicillin, metronidazole, clindamycin and tetracycline. The mean number of different bacterial species growing on the selective plates was higher in the Spanish patients, as was the % of resistant strains of most periodontal pathogens. A striking difference was observed in the frequency of occurrence of tetracycline-resistant periodontal pathogens. In Spain, 5 patients had 3 tetracycline resistant periodontal pathogens, whereas this was not observed in any of the Dutch patients. Conclusions: The widespread use of antibiotics in Spain is reflected in the level of resistance of the subgingival microflora of adult patients with periodontitis. [source] An efflux transporter PbrA and a phosphatase PbrB cooperate in a lead-resistance mechanism in bacteriaMOLECULAR MICROBIOLOGY, Issue 2 2009Anu Hynninen Summary The gene cluster pbrTRABCD from Cupriavidus metallidurans CH34 is thought to encode a unique, specific resistance mechanism for lead. However, the exact functions of these genes are unknown. In this study we examine the metal specificity and functions of pbrABCD by expressing these genes in different combinations and comparing their ability to restore Pb2+, Zn2+ and Cd2+ resistance in a metal-sensitive C. metallidurans strain DN440. We show that lead resistance in C. metallidurans is achieved through the cooperation of the Zn/Cd/Pb-translocating ATPase PbrA and the undecaprenyl pyrophosphate phosphatase PbrB. While PbrA non-specifically exported Pb2+, Zn2+ and Cd2+, a specific increase in lead resistance was observed when PbrA and PbrB were coexpressed. As a model of action for PbrA and PbrB we propose a mechanism where Pb2+ is exported from the cytoplasm by PbrA and then sequestered as a phosphate salt with the inorganic phosphate produced by PbrB. Similar operons containing genes for heavy metal translocating ATPases and phosphatases were found in several different bacterial species, suggesting that lead detoxification through active efflux and sequestration is a common lead-resistance mechanism. [source] Conjugation mediates transfer of the Ll.LtrB group II intron between different bacterial speciesMOLECULAR MICROBIOLOGY, Issue 5 2004Kamila Belhocine Summary Some self-splicing group II introns (ribozymes) are mobile retroelements. These retroelements, which can insert themselves into cognate intronless alleles or ectopic sites by reverse splicing, are thought to be the evolutionary progenitors of the widely distributed eukaryotic spliceosomal introns. Lateral or horizontal transmission of introns (i.e. between species), although never experimentally demonstrated, is a well-accepted model for intron dispersal and evolution. Horizontal transfer of the ancestral bacterial group II introns may have contributed to the dispersal and wide distribution of spliceosomal introns present in modern eukaryotic genomes. Here, the Ll.LtrB group II intron from the Gram-positive bacterium Lactococcus lactis was used as a model system to address the dissemination of introns in the bacterial kingdom. We report the first experimental demonstration of horizontal transfer of a group II intron. We show that the Ll.LtrB group II intron, originally discovered on an L. lactis conjugative plasmid (pRS01) and within a chromosomally located sex factor in L. lactis 712, invades new sites using both retrohoming and retrotransposition pathways after its transfer by conjugation. Ll.LtrB lateral transfer is shown among different L. lactis strains (intraspecies) (retrohoming and retrotransposition) and between L. lactis and Enterococcus faecalis (interspecies) (retrohoming). These results shed light on long-standing questions about intron evolution and propagation, and demonstrate that conjugation is one of the mechanisms by which group II introns are, and probably were, broadly disseminated between widely diverged organisms. [source] Microbiological examination of infected dental root canalsMOLECULAR ORAL MICROBIOLOGY, Issue 2 2004B. P. F. A. Gomes Objectives:, The aim of this study was to investigate the root canal microbiota of primary and secondary root-infected canals and the association of constituent species with specific endodontic signs and symptoms. Methods:, Microbial samples were taken from 60 root canals, 41 with necrotic pulp tissues (primary infection) and 19 with failed endodontic treatment (secondary infection). Strict anaerobic techniques were used for serial dilution, plating, incubation and identification. Results:, A total of 224 cultivable isolates were recovered belonging to 56 different bacterial species. Individual root canals yielded a maximum of 10 bacterial species. Of the bacterial isolates, 70% were either strict anaerobes or microphilic. The anaerobes most frequently isolated were: Peptostreptococcus micros (35%), Fusobacterium necrophorum (23.3%), Fusobacterium nucleatum (11.7%), Prevotella intermedia/nigrescens (16.7%), Porphyromonas gingivalis (6.7%) and Porphyromonas endodontalis (5%). The root canal microflora of untreated teeth with apical periodontitis was found to be mixed, comprising gram-negative and gram-positive and mostly anaerobic microorganisms and usually containing more than 3 species per canal. On the other hand, facultative anaerobic and gram-positive bacteria predominated in canals with failed endodontic treatment, which harbored 1,2 species per canal. Suggested relationships were found between anaerobes, especially gram-negatives, and the presence or history of pain, tenderness to percussion and swelling (P < 0.05). In particular, associations were found between: a) pain (n = 29) and P. micros (P < 0.01), P. intermedia/nigrescens and Eubacterium spp. (both P < 0.05); b) history of pain (n = 31) and P. micros (P < 0.01) Porphyromonas and Fusobacterium spp. (P < 0.05); c) tenderness to percussion (n = 29) and Porphyromonas spp. (P < 0.01), Peptostreptococcus and Fusobacterium spp. (P < 0.001); d) swelling (n = 20) and Peptostreptococcus spp. (P < 0.01), Porphyromonas and Enterococcus spp. (P < 0.05); e) wet canals (n = 33) and Porphyromonas and Fusobacterium spp. (P < 0.05); f) purulent exudate (n = 20) and Porphyromonas, Peptostreptococcus and Fusobacterium spp. (P < 0.05); previous endodontic treatment and Enterococcus faecalis, Streptococcus spp., P. micros, F. necrophorum (P < 0.05). Conclusions:, Our findings indicate potential complex interactions of species resulting in characteristic clinical pictures which cannot be achieved by individual species alone. They also indicate that the microbiota of primary infected canals with apical periodontitis differs in number and in species from the secondary infected canals by using the culture technique. [source] Structures of S. aureus thymidylate kinase reveal an atypical active site configuration and an intermediate conformational state upon substrate bindingPROTEIN SCIENCE, Issue 4 2006Masayo Kotaka Abstract Methicillin-resistant Staphylococcus aureus (MRSA) poses a major threat to human health, particularly through hospital acquired infection. The spread of MRSA means that novel targets are required to develop potential inhibitors to combat infections caused by such drug-resistant bacteria. Thymidylate kinase (TMK) is attractive as an antibacterial target as it is essential for providing components for DNA synthesis. Here, we report crystal structures of unliganded and thymidylate-bound forms of S. aureus thymidylate kinase (SaTMK). His-tagged and untagged SaTMK crystallize with differing lattice packing and show variations in conformational states for unliganded and thymidylate (TMP) bound forms. In addition to open and closed forms of SaTMK, an intermediate conformation in TMP binding is observed, in which the site is partially closed. Analysis of these structures indicates a sequence of events upon TMP binding, with helix ,3 shifting position initially, followed by movement of ,2 to close the substrate site. In addition, we observe significant conformational differences in the TMP-binding site in SaTMK as compared to available TMK structures from other bacterial species, Escherichia coli and Mycobacterium tuberculosis as well as human TMK. In SaTMK, Arg 48 is situated at the base of the TMP-binding site, close to the thymine ring, whereas a cis -proline occupies the equivalent position in other TMKs. The observed TMK structural differences mean that design of compounds highly specific for the S. aureus enzyme looks possible; such inhibitors could minimize the transfer of drug resistance between different bacterial species. [source] Design, synthesis, characterization and antibacterial properties of copper(II) complexes with chromone-derived compoundsAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 1 2010Zahid H. Chohan Abstract A new series of six chromone-derived compounds and their Cu(II) complexes was synthesized and characterized by their physical, spectral and analytical data The elemental analysis data of the complexes agree well with the proposed composition of the compounds, which were found to be dimeric in nature with two hydrazine molecules bridging the two copper atoms through coordination. The ligands and their Cu(II) complexes were screened for their in-vitro antibacterial activity against four Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Shigella flexneri) and two Gram-positive (Bacillus subtilis, Staphylococcus aureus) bacterial strains by the agar-well diffusion method. The ligands were found to exhibit either no or low to moderate activities against one or more of the bacterial species, whereas all the metal complexes exhibited moderate to high activities against different bacterial species. The ligands which were inactive before complexation turned active and less active ones became more active upon coordination with copper ions. Overall, the complexes 7,12 showed comparatively much higher activities than the ligands. Copyright © 2009 John Wiley & Sons, Ltd. [source] |