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Microbial Species (microbial + species)
Selected AbstractsLimits of life in hostile environments: no barriers to biosphere function?ENVIRONMENTAL MICROBIOLOGY, Issue 12 2009Jim P. Williams Summary Environments that are hostile to life are characterized by reduced microbial activity which results in poor soil- and plant-health, low biomass and biodiversity, and feeble ecosystem development. Whereas the functional biosphere may primarily be constrained by water activity (aw) the mechanism(s) by which this occurs have not been fully elucidated. Remarkably we found that, for diverse species of xerophilic fungi at aw values of , 0.72, water activity per se did not limit cellular function. We provide evidence that chaotropic activity determined their biotic window, and obtained mycelial growth at water activities as low as 0.647 (below that recorded for any microbial species) by addition of compounds that reduced the net chaotropicity. Unexpectedly we found that some fungi grew optimally under chaotropic conditions, providing evidence for a previously uncharacterized class of extremophilic microbes. Further studies to elucidate the way in which solute activities interact to determine the limits of life may lead to enhanced biotechnological processes, and increased productivity of agricultural and natural ecosystems in arid and semiarid regions. [source] Estimation of microbial cover distributions at Mammoth Hot Springs using a multiple clone library resampling methodENVIRONMENTAL MICROBIOLOGY, Issue 7 2006Héctor García Martín Summary We propose the use of cover as a quick, low-resolution proxy for the abundance of microbial species, which reduces polymerase chain reaction bias. We showcase this concept in a computation that uses clone library information from travertine-forming hot springs in Yellowstone National Park to provide estimates of relative covers at different locations within the spring system. Samples were used from two media: the water column and the travertine substrate. The cover distribution is found to approximate a power law for samples within the water column. Significant commonality of species with the highest cover is observed in the water column for all locations, but not for species present in the substrate at different locations or between media at the same location. [source] Microbial diversity of inflamed and noninflamed gut biopsy tissues in inflammatory bowel diseaseINFLAMMATORY BOWEL DISEASES, Issue 6 2007Shadi Sepehri MD Abstract Background: Inflammatory bowel disease (IBD) is a chronic gastrointestinal condition without any known cause or cure. An imbalance in normal gut biota has been identified as an important factor in the inflammatory process. Methods: Fifty-eight biopsies from Crohn's disease (CD, n = 10), ulcerative colitis (UC, n = 15), and healthy controls (n = 16) were taken from a population-based case-control study. Automated ribosomal intergenic spacer analysis (ARISA) and terminal restriction fragment length polymorphisms (T-RFLP) were used as molecular tools to investigate the intestinal microbiota in these biopsies. Results: ARISA and T-RFLP data did not allow a high level of clustering based on disease designation. However, if clustering was done based on the inflammation criteria, the majority of biopsies grouped either into inflamed or noninflamed groups. We conducted statistical analyses using incidence-based species richness and diversity as well as the similarity measures. These indices suggested that the noninflamed tissues form an intermediate population between controls and inflamed tissue for both CD and UC. Of particular interest was that species richness increased from control to noninflamed tissue, and then declined in fully inflamed tissue. Conclusions: We hypothesize that there is a recruitment phase in which potentially pathogenic bacteria colonize tissue, and once the inflammation sets in, a decline in diversity occurs that may be a byproduct of the inflammatory process. Furthermore, we suspect that a better knowledge of the microbial species in the noninflamed tissue, thus before inflammation sets in, holds the clues to the microbial pathogenesis of IBD. (Inflamm Bowel Dis 2007) [source] Probiotics and the management of inflammatory bowel diseaseINFLAMMATORY BOWEL DISEASES, Issue 3 2004FRCPC, Richard N. Fedorak MD Abstract The demonstration that immune and epithelial cells can discriminate between different microbial species has extended our understanding of the actions of probiotics beyond simple barrier and antimicrobial concepts. Several probiotic mechanisms of action, relative to inflammatory bowel disease, have been elucidated: (1) competitive exclusion, whereby probiotics compete with microbial pathogens for a limited number of receptors present on the surface epithelium; (2) immunomodulation and/or stimulation of an immune response of gut-associated lymphoid and epithelial cells; (3) antimicrobial activity and suppression of pathogen growth; (4) enhancement of barrier function; and (5) induction of T cell apoptosis in the mucosal immune compartment. The unraveling of these mechanisms of action has led to new support for the use of probiotics in the management of clinical inflammatory bowel disease. Though level 1 evidence now supports the therapeutic use of probiotics in the treatment of postoperative pouchitis, only levels 2 and 3 evidence is currently available in support of the use of probiotics in the treatment of ulcerative colitis and Crohn's disease. Nevertheless, one significant and consistent finding has emerged during the course of research in the past year: not all probiotic bacteria have similar therapeutic effects. Rigorously designed, controlled clinical trials are vital to investigate the unresolved issues related to efficacy, dose, duration of use, single or multi-strain formulation, and the concomitant use of prebiotics, synbiotics, or antibiotics. [source] Thymol and modified atmosphere packaging to control microbiological spoilage in packed fresh cod hamburgersINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2009Maria Rosaria Corbo Summary A study on the use of mild technologies to produce packaged fish hamburgers was presented. In particular, the antimicrobial effect of some natural compounds (carvacrol, eugenol, thymol, green tea extract, rosemary extract, grapefruit seed extract and lemon extract), at various concentrations (500,10 000 ppm), was screened in vitro against the main fish spoilage micro-organisms (Shewanella putrefaciens and Photobacterium phosphoreum). Lemon extract and thymol, in combination with modified atmosphere packaging, showed the greatest inhibition activity, therefore, thymol was subsequently used as an ingredient for producing fish hamburgers. Results pointed out that this combination is effective in controlling the growth of microbial species mainly involved in fresh fish spoilage; in particular, it significantly (P < 0.05) reduced the growth rate of bacterial population, performing about 4.8 log CFU g,1 and 6.5 log CFU g,1 reduction of the hydrogen sulphide producing bacteria and psychrotrophic aerobic specific spoilage organisms cell load, respectively, if compared with the control. [source] Ecophysiological attributes of a Lactobacillus sp. and a Pseudomonas sp. on sterile beef fillets in relation to storage temperature and film permeabilityJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2001E. Tsigarida Aims:,To determine the combined effect of packaging film and temperature on the rate and type of end-products caused by the growth of two main contrasting prevailing organisms in air and 100% CO2, Pseudomonas sp. and Lactobacillus sp., respectively. Methods and Results:,Pseudomonas sp. and Lactobacillus sp. were inoculated individually on sterile meat fillets. The samples were packed in air or 100% CO2, using a high and a low permeable film, and stored at 0 and 10°C. Pseudomonas sp. grew aerobically and in 100% CO2 using high permeable film at both storage temperatures, while film permeability significantly affected the growth of Lactobacillus sp. only at 10°C. Enzymatic kits and HPLC and GC analysis were used to determine the chemical changes of the samples throughout storage. Pseudomonas sp. presented a greater rate of consumption of glucose and lactate than Lactobacillus sp. in samples stored aerobically or with high permeable film. Propanol-1 and two unidentified organic acids were present only in samples inoculated with Pseudomonas sp., while acetaldehyde, ethanol, diacetyl and acetoin were detected in samples inoculated with Lactobacillus sp. Conclusions:,Since different microbial species and introduction of new packaging methods affect spoilage reactions of meat either qualitatively or quantitatively, a combination of several chemical indicators should be thoroughly investigated. Significance and Impact of the Study:,The present study provides information on how and when such potential indicators can be exploited for the benefit of the industry and consumer. [source] Pro-inflammatory biomarkers during experimental gingivitis in patients with type 1 diabetes mellitus: a proof-of-concept studyJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 1 2010Giovanni E. Salvi Abstract Aim: To compare gingival crevicular fluid (GCF) biomarker levels and microbial distribution in plaque biofilm (SP) samples for subjects with type 1 diabetes (T1DM) versus healthy subjects without diabetes during experimental gingivitis (EG). Materials and Methods: A total of nine T1DM patients and nine healthy controls of age and gender similar to the T1DM patients were monitored for 35 days during EG. Hygiene practices were stopped for 3 weeks, and GCF, SP, plaque index (PI) and gingival index were determined. IL-1,, IL-8, MMP-8 and MMP-9 were quantified by enzyme-linked immunosorbent assay, and SP samples were assessed by DNA,DNA hybridization for a panel of 40 subgingival microbial species. Results: IL-1, levels in T1DM patients were elevated compared with healthy individuals, and showed differences between groups at 7,21 days while healthy patients showed IL-1, increases from baseline to 14,21 days (p<0.05). Differences were observed in MMP-9 levels between patients with and without T1DM at 7,14 days (p<0.05). Orange complex species and PI measurements displayed a superior correlation with biomarker levels when compared with other complexes or clinical measurements during EG. Conclusions: The mean GCF biomarker levels for IL-1, and MMP-8 were most significantly elevated in T1DM subjects compared with healthy individuals during EG, not resulting from differences in the mean PI or microbial composition. [source] Absence of a specific subgingival microflora in adults with Down's syndromeJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 11 2001W. Reuland-Bosma Abstract Background: Periodontal disease in Down's syndrome (DS) is generally characterized by a high degree of bone loss. Bone loss of 5 mm or more is observed in 70% of these subjects. Among DS subjects, considerable differences in disease progression occur. So far, no studies have been conducted in which specific properties of the subgingival microflora have been related to the condition observed. Aims: To investigate (1) the subgingival microflora in DS subjects and other mentally retarded (control) individuals which were matched to the utmost and (2) to investigate the subgingival microflora of a "low-risk" and a " high-risk" group formed in DS subjects. Material and Methods: 17 DS subjects and 17 control subjects were matched with respect to age, plaque level and bleeding on probing. In addition, the DS group was divided in a "low-risk" group (0,2 teeth lost due to periodontal disease n=6) and a "high-risk"group (6,13 teeth lost due to periodontal disease n=11). Prevalence and proportions of the putative periodontal pathogens Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Bacteroides forsythus, Peptostreptococcus micros, Fusobacterium nucleatum and Campylobacter rectus in the subgingival plaque were determined using anaerobic culture techniques. No differences in the prevalence of distinct suspected periodontopathic bacteria and bacterial subgingival composition between the DS group and the control group could be established. Also no differences in the prevalence of the seven investigated microbial species between the "low-risk" and the "high-risk" group were observed. Conclusions: Because of the lack of differences in microflora between the DS group and the control group, a specific effect of the microbiological composition in the periodontal status of subjects with DS can be excluded in this population. Host factors constitute the more likely explanation of the differences observed in DS. Zusammenfassung Basis: Die parodontale Erkrankung beim Down Syndrom (DS) ist allgemein durch einen hohen Grad von Knochenverlust charakterisiert. Knochenverlust von 5 mm und mehr wird bei 70% der Personen beobachtet. Unter den DS Personen bestehen beträchtliche Differenzen in der Erkrankungsprogression. Bis heute sind keine Studien durchgeführt worden, in welchen die spezifischen Eingenschaften der subgingivalen Mikroflora in Beziehung zu den Bedingungen beobachtet wurden. Ziele: Untersuchung (1) der subgingivalen Mikroflora bei DS Personen und anderen mental retardierten (Kontrollen) Personen, die zu einer größten gemischt wurden und (2) der subgingivalen Mikroflora von Gruppen mit "geringem Risiko" und Gruppen mit "hohem Risiko" bei DS Personen. Material und Methoden: 17 DS Personen mit 17 Kontrollpersonen wurden im Hinblick auf Alter, Plaquemenge und Blutung auf Provokation eingeteilt. Zusätzlich wurde die DS Gruppe in "geringes Risiko" (0,2 Zähne infolge von parodontaler Erkrankung verloren, n=6) und in "hohes Risiko" (6,13 Zähne infolge parodontaler Erkrankung verloren, n=11) eingeteilt. Das Vorkommen und die Relationen von putativen parodontalen Pathogenen Actinobacillus actinomycetemcomitants, Porphyromonas gingivalis, Prevotella intermedia, Bacteroides forsythus, Peptostreptococcus micros, Fusobacterium nucleatum und Campylobacter rectus in der subgingivalen Plaque wurden mit anaerober Kulturtechnik bestimmt. Ergebnisse: Es konnten keine Differenzen in der Prävalenz der bezeichneten parodontopathogenen Bakterien und der bakteriellen subgingivalen Zusammensetzung zwischen DS Gruppe und der Kontrollgruppe beobachtet werden. Auch zwischen der Gruppe "geringes Risiko" und "hohes Risiko" wurden keine Differenzen in der Prävalenz der 7 untersuchten Spezies beobachtet. Schlußfolgerungen: Weil keine Differenzen in der Mikroflora zwischen DS Gruppe und der Kontrollgruppe vorhanden sind, kann ein spezifischer Effekt der mikrobiologischen Zusammensetzung beim parodontalen Status der Personen mit DS in dieser Population ausgeschlossen werden. Für die Erklärung der Differenzen, die bei den DS Personen beobachtet werden, sind die Wirtsfaktoren mehr wahrscheinlich. Résumé Origine: La maladie parodontale lors du syndrôme de Down (DS) est généralement caractérisée par une importante perte osseuse. Cette perte osseuse atteint 5 mm ou plus chez 70% de ces malades. Parmi les sujets DS, des différences considérables dans la progression de cette maladie se manifestent. Aucune étude n'a encore été entreprise dans laquelle la microflore sous-gingivale a été mise en relation avec les conditions observées. But: Le but de cette étude a été (1) d'analyser la microflore sous-gingivale chez les sujets DS et d'autres retardés mentaux servant de contrôles et (2) mieux connaître la microflore sous-gingivale chez les groupes de patients DS avec faible et haut risques. Matériaux et méthodes: 17 sujets DS et 17 sujets contrôles ont été analysés de manière parallèle en fonction de l'âge, du niveau de plaque dentaire et du saignement au sondage. De plus, le groupe DS était scindé en deux sous-groupes: "petit risque" (0 à 2 dents perdues pour cause de maladie parodontale; n=6), et "haut risque" (6 à 13 dents perdues; n=11). La fréquence globale et les proportions de pathogènes parodontaux putatifs l'Actinobacillus actinomycetemcomitans, le Porphyromonas gingivalis, le Prevotella intermedia, le Bacteroides forsythus, le Peptostreptococcus micros, le Fusobacterium nucleatum et le Campylobacter rectus dans la plaque sous-gingivale ont été déterminés en utilisant des techniques de culture anaérobie. Résultats: Aucune différence dans la fréquence globlale de ces bactéries ni dans la composition de la flore sous-gingivale n'a été trouvée entre le groupe DS et le groupe contrôle. Il n'y avait également aucune différence entre les sous-groupes à faible et à haut risques. Conclusions: Parce qu'aucune différence n'a été décelée dans la microflore entre les groupes DS et contrôle, aucun effet spécifique de leur flore sous-gingivale ne pourrait être responsable; les facteurs de l'hôte constituent très vraisemblablement l'explication des différences observées chez les sujets DS. [source] Relationship of cigarette smoking to the subgingival microbiotaJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 5 2001A. D. Haffajee Abstract Background: The relationship of cigarette smoking to the composition of the subgingival microbiota is not clear. Some studies indicated higher levels of certain species in smokers, while other studies failed to detect differences in the microbiota between subjects with different smoking histories. Thus, the purpose of the present investigation was to examine the prevalence, proportions and levels of the subgingival species in adult subjects who were current, past or never smokers. Method: 272 adult subjects ranging in age from 20,86 years with at least 20 teeth were recruited for study. Smoking history was obtained using a questionnaire. Clinical measures were taken at 6 sites per tooth at all teeth excluding third molars at a baseline visit. Subgingival plaque samples were taken from the mesial surface of all teeth excluding third molars in each subject at baseline and assayed individually for counts of 29 subgingival species using checkerboard DNA-DNA hybridization. Subjects were subset according to smoking history into never (n=124), past (n=98) and current smokers (n=50). Uni-variate and multi-variate analyses were used to seek associations between smoking category and the counts, proportions and prevalence of subgingival species. Results: Greater differences were observed for the prevalence (% of sites colonized) of the test species in the 3 smoking groups than were observed for counts or proportions of total counts. Members of the orange and red complexes including E. nodatum, F. nucleatum ss vincentii, P. intermedia, P. micros, P. nigrescens, B. forsythus, P. gingivalis and T. denticola were significantly more prevalent in current smokers than in the other 2 groups. The difference in prevalence between smokers and non-smokers was due to greater colonization at sites with pocket depth <4 mm. Stepwise multiple linear regression analysis indicated that combinations of the prevalence of 5 microbial species and pack years accounted for 44% of the variance for mean pocket depth (p<0.000001), while the prevalence of 3 microbial taxa along with age, pack years, current smoking and gender accounted for 31% of the variance in mean attachment level (p<0.000001). The difference in prevalence between current and never smokers of all members of the red complex and 8 of 12 members of the orange complex was significantly greater in the maxilla than in the mandible. Conclusions: The major difference between the subgingival microbiota in subjects with different smoking history was in the prevalence of species rather than counts or proportions. The greater extent of colonization in smokers appeared to be due to greater colonization at pocket depths <4 mm. Differences in colonization patterns between current and never smokers were greater in the maxilla than in the mandible. Zusammenfassung Grundlagen: Die Beziehung zwischen dem Zigarettenrauchen und der Zusammensetzung der subgingivalen Mikroflora ist nicht klar. Einige Studien verweisen auf höhere Titer von bestimmten Spezies bei Rauchern, während andere Studien keine Unterschiede in der Mikroflora zwischen Personen mit unterschiedlichem Raucher- oder Nichtraucherverhalten nachweisen konnten. Daher war der Zweck der vorliegenden Studie die Untersuchung von Prävalenz, Anteil und Titer der subgingivalen Spezies bei erwachsenen Patienten, die zur Zeit, früher oder niemals Raucher waren. Methode: Für die Studie wurden 272 erwachsene Patienten im Alter zwischen 20 und 86 Jahren und wenigstens 20 Zähnen rekrutiert. Die Anamnese des Rauchverhaltens wurde under Verwendung eines Fragebogens durchgeführt. Bei einer Eingangsuntersuchung erfolgten die klinischen Messungen an 6 Stellen pro Zahn bei allen Zähnen außer den dritten Molaren. Bei der Eingangsuntersuchung wurden, bei allen Zähnen außer den dritten Molaren, von den Mesialflächen subgingivale Plaqueproben entnommen. Für die einzelnen Flächen wurde die Anzahl von 29 subgingivalen Spezies mittels Schachbrett-DNA-DNA-Hybridisierung bestimmt. Die Patienten wurden entsprechend der Rauchervorgeschichte in folgende Gruppen eingeteilt: niemals (n=124), früher (n=98) und zur Zeit (n=50). Um Assoziationen zwischen den Rauchkategorien und der Anzahl, dem Anteil und der Prävalenz der subgingivalen Spezies herauszufinden wurden eine uni-variate und multi-variate Analyse verwendet. Ergebnisse: Es wurden größere Unterschiede zwischen den 3 Gruppen hinsichtlich der Prävalenz der Testspezies (% der Taschen die kolonisiert waren) beobachtet als bei der Anzahl oder dem Anteil an der Gesamtzahl der Keime beobachtet wurde. Die Prävalenz der Keime des orangen und roten Komplexes einschließlich. E. nodatum, F. nucleatum ss vincentii, P. intermedia, P. micros, P. nigrescens, B. forsythus, P. gingivalis und T. denticola war bei den aktuellen Rauchern stärker prävalent als in den anderen beiden Gruppen. Die Differenz in der Prävalenz zwischen Rauchern und Nichrauchern wurde verursacht durch eine stärkere Kolonisation in Taschen mit einer Taschentiefe <4 mm. Die schrittweise multiple lineare Regressionsanalyse zeigte, dass Kombinationen der Prävalenz von 5 mikrobiellen Spezies und der Packungsjahre für 44% der Varianz der mittleren Taschentiefe verantwortlich waren (p<0.000001), während die Prävalenz von 3 mikrobiellen Taxa zusammen mit Alter, Packungsjahre, Raucherstatus und Geschlecht für 31% der Varizna im mittleren Attachmentniveau verantwortlich waren (p<0.000001). Die Differenz in der Prävalenz zwischen den aktuellen Rauchern und den die niemals rauchten war für alle Keime der roten Komplexes und 8 von 12 Keimen des orangen Komplexes im Oberkiefer signifikant größer als im Unterkiefer. Schlussfolgerung: Der Hauptunterschied zwischen der subgingivalen Mikroflora bei Patienten mit unterschiedlicher Rauchervorgeschichte lag mehr bei der Prävalenz der Spezies als bei der Anzahl der Keime oder den Anteilen an der Gesamtflora. Das größere Maß an Kolonisation bei den Rauchern schien durch eine stärkere Kolonisation in Taschen <4 mm verursacht zu sein. Differenzen im Kolonisationsmuster zwischen aktuellen Rauchern und Nichtrauchern die niemals rauchten waren im Oberkiefer größer als im Unterkiefer. Résumé Origine, but: La relation entre l'usage de la cigarette et la composition de la microflore sous gingivale n'est pas claire. Certaines études indiquent d'importants niveaux de certaines espèces chez les fumeurs, alors que d'autres études n'arrivent pas à détecter de différences dans la micrflore entre des sujets ayant des histoires tabagiques différentes. Aussi, le propos de cette recherche est d'examiner la prévalence, les proportions et le niveau des espèces sous gingivales chez des sujets adultes fumeurs, anciens fumeurs ou non-fumeurs. Méthodes: 272 sujets adultes, âgès de 20 à 86 ans, ayant au moins 20 dents furent recrutés pour l'étude. L'histoire tabagique fut obtenue à l'aide d'un questionnaire. Des mesures cliniques furent prises sur 6 sites par dents, sur toutes les dents à l'exception des troisièmes molaires lors de la première visite. Des échantillons de plaque sous gingivale étaient prélevés sur la face mésiale de chaque dent à l'exception des troisièmes molaires chez chaque sujet lors de la première visite et individuellement testés pour le comptage de 29 espèces sousgingivales par hybridisation en damier ADN-ADN. Les sujets étaient groupés en sous ensembles en fonction de leur histoire tabagique en non-fumeurs (n=124), ancien fumeurs (n=98), et fumeurs (n=50). Des analyses monovariées et multivariées furent utilisées pour rechercher des associations entre les catégories de fumerus et les comptages, proportions et prévalences des espèces bactériennes. Résultats: De plus grandes différences étaient observées pour la prévalence (% de sites colonisés) des expèces testées dans les 3 groupes, que pour le comptage ou la proportion des comptages totaux. Les membres des complexes orange et rouge dont E. nodatum, F. nucléatum ss vicentii, P. intermedia, P. micros, P. nigrescens, B. forsythus, P. gingivalis, et T. denticolaétait significativement plus prévalent chez les fumeurs que dans les 2 autres groupes. La différence de prévalence entre les fumeurs et les non-fumeurs était due à une plus grande colonisation des sites dont la profondeur de poche était <4 mm. L'analyse par régression linéaire multiple stepwise indiquait que les combinaisons de la prévalence de 5 espèces microbiennes et les paquets-années comptaient pour 44% de la variance pour la moyenne de profondeur de poche (p<0.000001), alors que la prévalence de 3 taxons microbiens avec l'âge, les paquets-années, le tabagisme présent et le sexe comptaient pour 31% de la variance pour le niveau d'attache moyen (p<0.000001). La différence de prévalence entre les fumerus en activité et les non-fumeurs (jamais fumé) de tous les membres du complexe rouge et de 8 des 12 membres du complexe orange était significativement plus élevée au maxillaire qu'à la mandibule. Conclusions: La différence majeure entre les microflores sous gingivales chez les sujets ayant des histoires tabagiques différentes se trouvaient dans la prévalence des expèces plutôt que dans leurs quantité ou leurs proportions. La plus grande importance de colonisation chez les fumerus apparaît être dûe à une colonisation plus grande dans les poches <4 mm. Des différences des caractéristiques de colonisation entre les fumerus actifs et les personnes n'ayant jamais fuméétaient plus importantes au maxillaire qu'à la mandibule. [source] The microbiota on different oral surfaces in healthy childrenMOLECULAR ORAL MICROBIOLOGY, Issue 3 2009W. Papaioannou Introduction:, Knowledge of the early oral colonization patterns could provide a better understanding of oral biofilm development and disease initiation that in turn could be the basis for early preventive programmes. Methods:, Microbial samples were collected from five different oral habitats from a total of 93 children (age 3,12 years), attending the Dental School of the University of Athens, who were split into three age groups. A total of 38 microbial species were sought out by the checkerboard DNA,DNA hybridization technique. Results:, All of the test species, except Parvimonas micra and Porphyromonas gingivalis, differed significantly among sample locations providing quite distinct microbial profiles for the different oral surfaces. Supragingival and subgingival plaque had similar profiles and exhibited higher proportions of Actinomyces species and Green complex while soft tissue samples were dominated by streptococci of the Yellow complex. The profiles of the tongue dorsum and saliva were also similar. Many of the species were in similar proportions in all three age groups for a given location. Periodontal pathogens showed increases in proportions with increasing age. Specifically, the Red complex species (Tannerella forsythia, P. gingivalis, Treponema denticola) showed a significant increase in proportion with age (P < 0.05) in all sample locations. Conclusions:, The results showed a pattern of colonization in children similar to that previously found in adults. Differences in the profile between age groups suggest a gradual maturation of the oral microbiota, with it being made up of an increasing number of Orange and Red complex species. [source] Microbiological analysis of infected root canals from symptomatic and asymptomatic teeth with periapical periodontitis and the antimicrobial susceptibility of some isolated anaerobic bacteriaMOLECULAR ORAL MICROBIOLOGY, Issue 5 2003R. C. Jacinto The purpose of the present study was to investigate the correlation between the composition of the bacterial flora isolated from infected root canals of teeth with apical periodontitis with the presence of clinical signs and symptoms, and to test the antibiotic susceptibility of five anaerobic bacteria mostly commonly found in the root canals of symptomatic teeth against various substances using the E-test. Microbial samples were taken from 48 root canals, 29 symptomatic and 19 asymptomatic, using adequate techniques. A total of 218 cultivable isolates were recovered from 48 different microbial species and 19 different genera. Root canals from symptomatic teeth harbored more obligate anaerobes and a bigger number of bacterial species than the asymptomatic teeth. More than 70% of the bacterial isolates were strict anaerobes. Statistical analysis used a Pearson Chi-squared test or a one-sided Fisher's Exact test as appropriate. Suggested relationships were found between specific microorganisms, especially gram-negative anaerobes, and the presence of spontaneous or previous pain, tenderness to percussion, pain on palpation and swelling amoxicillin, amoxicillin + clavulanate and cephaclor were effective against all the strains tested. The lowest susceptibility rate was presented by Prevotella intermedia/nigrescens against Penicillin G. Our results suggested that specific bacteria are associated with endodontic symptoms of infected teeth with periapical periodontitis and the majority of the anaerobic bacterial species tested were susceptible to all antibiotics studied. [source] Non-host resistance in plants: new insights into an old phenomenonMOLECULAR PLANT PATHOLOGY, Issue 3 2005THORSTEN NÜRNBERGER SUMMARY Resistance of an entire plant species to all isolates of a microbial species is referred to as non-host or species resistance. An interplay of both constitutive barriers and inducible reactions comprises the basis for this most durable form of plant disease resistance. Activation of inducible plant defence responses is probably brought about by the recognition of invariant pathogen-associated molecular patterns (PAMP) that are characteristic of whole classes of microbial organisms. PAMP perception systems and PAMP-induced signalling cascades partially resemble those known to mediate activation of innate immune responses in animals, suggesting an evolutionarily ancient molecular concept of non-self recognition and immunity in eukaryotes. Genetic dissection has recently provided clues for SNARE-complex-mediated exocytosis and directed vesicle trafficking in executing plant non-host resistance. Recent functional analysis of bacterial effector proteins indicates that establishment of infection in susceptible plants is associated with suppression of plant species resistance. [source] Recent developments in the molecular discrimination of formae speciales of Fusarium oxysporumPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 8 2008Bart Lievens Abstract Rapid and reliable detection and identification of potential plant pathogens is required for taking appropriate and timely disease management measures. For many microbial species of which all strains generally are plant pathogens on a known host range, this has become quite straightforward. However, for some fungal species this is quite a challenge. One of these is Fusarium oxysporum Schlechtend:Fr., which, as a species, has a very broad host range, while individual strains are usually highly host-specific. Moreover, many strains of this fungus are non-pathogenic soil inhabitants. Thus, with regard to effective disease management, identification below the species level is highly desirable. So far, the genetic basis of host specificity in F. oxysporum is poorly understood. Furthermore, strains that infect a particular plant species are not necessarily more closely related to each other than to strains that infect other hosts. Despite these difficulties, recently an increasing number of studies have reported the successful development of molecular markers to discriminate F. oxysporum strains below the species level. Copyright © 2008 Society of Chemical Industry [source] | ||||||||||||||||