179 research outputs found
Etablierung eines Pseudomonas aeruginosa Biofilmassays zur Antibiotikawirksamkeitstestung
No full textDie Hauptmortalitätsursache von Mukoviszidosepatienten ist die Abnahme der Lungenfunktion aufgrund von bakteriellen Infektionen, wobei P. aeruginosa den essentiellsten Erreger darstellt. Bei chronischen Infektionen bildet P. aeruginosa in der Lunge Biofilme aus. Biofilme sind eine Gemeinschaft von Mikroorganismen, welche an eine abiotische oder biotische Oberfläche haften und von extrazellulären Komponenten (Polysaccharide, Proteine und DNA) umgeben sind. Dieser Biofilm schützt die Bakterien gegenüber antimikrobiellen Substanzen. Die derzeitigen in vitro Assays beziehen sich auf das Wachstum der Bakterien in planktonischer Form. Dies stellt die Situation in einer chronischen Infektion allerdings nur unzureichend dar, da die Bakterien dort in Biofilmen auftreten. Aus diesem Grund war das Ziel der vorliegenden Bachelorarbeit einen in vitro Biofilm-Assay in der Arbeitsgruppe zu etablieren und dieses mit der traditionellen Bestimmung der minimalen Hemmkonzentration (MHK) zu vergleichen. Zudem sollte untersucht werden, ob eine schnellere Bestimmung der Keimvitalität über die Messung der respiratorischen Aktivität (Resazurin-Assay und CTC-Assay) möglich ist. Für den in vitro Biofilm-Assay wurden die Biofilme von den P. aeruginosa Stämmen PAO1 und ATCC 9027 in 96 Well Mikrotiterplatten für 24 Stunden angezogen und nachfolgend für 24 Stunden mit verschiedenen Konzentrationen von Ceftazidim und Tobramycin behandelt. Anschließend wurden die Biofilme resuspendiert und die Lebendkeimzahl durch einen Verdünnungsausstrich bestimmt und mit dem MHK verglichen. Die Ergebnisse der MHK zeigte deutlich, dass die Bakterien in ihrer planktonischen Form sowohl von Ceftazidim als auch von Tobramycin bereits in niedrigen Konzentrationen in ihrem Wachstum gehemmt werden. Aus dem in vitro Biofilm-Assay ging hervor, dass die Bakterien auch bei sehr hohen Ceftazidimkonzentrationen (10 mg/ml) keinen Verlust der Vitalität aufwiesen. Tobramycin hemmt die in Biofilmen gewachsenen Bakterien erst in deutlich höheren Konzentrationen. Der Vergleich der MHK und des in vitro Biofilm-Assays zeigt, dass unterschiedliche Antibiotikakonzentrationen notwendig sind, um das Wachstum der Bakterien zu hindern. Somit stellt der in vitro Biofilm Assay im Vergleich zur MHK ein prädiktiveres Modell dar, um die Wirksamkeit von Antibiotika in Biofilm-assoziierten Infektionen zu überprüfen. Eine Bewertung der Keimvitalität im Biofilm über die metabolische Aktivität mittels Resazurin und CTC Färbung ist nur bedingt möglich, da die unterschiedlichen Stämme hohe Permeabilitätsunterschiede für die Farbstoffe aufwiesen.The decline of pulmonary function is the major cause of mortality for patients with cystic fibrosis due to bacteria infections, such as infection with P. aeruginosa. This essential pathogen generates a biofilm in the lungs during chronic infections. Biofilms are associations of microorganisms, which adhere on an abiotic and biotic surface and are enclosed from extracellular components such as polysaccharides, proteins and DNA. This protects the bacteria against antimicrobial substances. Current in-vitro assays showed an insufficient representation of the in-vivo situation, because they refer to bacteria growth in planktonic environment. Therefore, the aim of this bachelorthesis was to establish an in vitro biofilm-assay for testing the efficiency of antibiotics and to compare this assay with the traditional method of minimal inhibitory concentration (MIC). Furthermore, it was to investigate whether it is possible to determine the vitality of the pathogens also by measuring the respiratory activity (Resazurin-Assay und CTC-Assay). P. aeruginosa PAO1 and ATCC 9027 were used for in vitro biofilm-assay, cultivated into 96-well plates for 24 hours and treated with different concentrations of Ceftazidim and Tobramycin for additional 24 hours. Afterwards the biofilm was resuspended and the viable count was determined through a dilution streak and compared with MIC-assay. The results of the MIC-assay demonstrate that the bacteria were inhibited through Ceftazidim and Tobramycin. The in vitro biofilm-assay reflects that the bacteria treated with a high concentration of Ceftazidim (10 mg/ml) indicated a pronounced vitality. Tobramycin inhibited the growth of bacteria in biofilms. However, a higher antibiotic-concentration is required for MIC-assay. The comparison of in vitro biofilm- and MIC-assays demonstrate that higher antibiotic-concentrations are necessary to inhibit the growth of bacteria. Thus the in vitro biofilm-assay is better to verify the efficiency of antibiotics to infections with biofilms. The Resazurin- and CTC-assay is not suitable, because different strains indicated high differences in permeability
Serological and molecular detection as well as typing of Leptospira spp. in foxes, raccoons, and other wild carnivores in North-Eastern Germany, 2021-2022.
No full textLeptospirosis is a worldwide zoonosis caused by pathogenic Leptospira spp. While the latter are reported from various mammal hosts such as humans, dogs, or rodents, less is known about their presence in wild carnivores. We therefore investigated the presence of Leptospira spp. in foxes, raccoons, badgers, raccoon dogs, and martens in North-Eastern Germany. Kidney, urine, and blood specimens obtained from legally hunted or road-killed animals were tested by real-time PCR and by serogroup specific antibody detection for the presence of Leptospira spp. Additionally, kidney and urine specimens were tested by real-time PCR for the presence of Brucella spp. and Francisella tularensis, with all being negative for these two zoonotic pathogens. Leptospira spp. were detected by PCR in 12.6 % (n = 21/166) and serologically in 26.2 % (n = 53/202) of tissue and serum samples, respectively. Antibodies to 15 different serogroups were identified with Javanica (n = 25) and Bataviae (n = 12) being predominant. A high sero-prevalence of 34.0 % and 18.6 % in foxes and raccoons, respectively, and the presence of ST17 associated with human and animal leptospirosis indicates a reservoir and the zoonotic potential of these wild animals
Human Activity and Forest Degradation Threaten Populations of the Nigeria–Cameroon Chimpanzee (Pan troglodytes ellioti) in Western Cameroon
No full textAbstract
Increased human activities such as commodity-led deforestation, extension of agriculture, urbanization, and wildfires are major drivers of forest loss worldwide. In Cameroon, these activities cause a loss of suitable primate habitat and could ultimately threaten the survival of chimpanzees (
Pan troglodytes
). We derived independent estimates of the population size of the Endangered Nigeria–Cameroon chimpanzee (
Pan troglodytes ellioti
) in Kom-Wum Forest Reserve, Cameroon, and surrounding unprotected forest areas through 1) direct observations, 2) camera trapping, 3) distance sampling, 4) marked nest counts, and 5) standing crop nest counts. In addition, we georeferenced signs of chimpanzee and human activity along line transects. We used a generalized linear mixed model to predict the occurrence of chimpanzees in response to edge length (measured as the perimeter of core forest patches), core area of forest patches (measured as area of forest patches beyond an edge width of 100 m), habitat perforation (measured as the perimeter of nonforested landscape within core forest patches), patch size(measured as area of forest patches), and forest cover. Chimpanzee density estimates ranged from 0.1 (direct observation) to 0.9 (distance sampling) individuals km
−2
depending on estimation method with a mean nest group size of 7 ± 5.4 (SD). The mean encounter rate for signs of chimpanzee activity was significantly higher in mature forests (2.3 signs km
−1
) than in secondary forests (0.3 signs km
−1
) and above 1000 m elevation (4.0 signs km
−1
) than below 1000 m (1.0 signs km
−1
). The mean encounter rate for signs of human activity was significantly higher in secondary (8.0 signs km
−1
) than in mature forests (0.9 signs km
−1
). Secondary forests, habitat perforation, and edge length had a significant negative effect on the occurrence of chimpanzee signs. Overall, human activity and forest degradation affected the number of observed chimpanzee signs negatively. Regular antipoaching patrols and reforestation programs in degraded areas could potentially reduce threats to populations of endangered species and may increase suitable habitat area
Tool use by Nigeria-Cameroon chimpanzees for driver ant predation in Kom-Wum Forest Reserve, North-West Region Cameroon
No full textMapping suitable habitat for Nigeria–Cameroon chimpanzees in Kom-Wum Forest Reserve, North-Western Cameroon
No full textAbstract Great apes lose suitable habitats required for their reproduction and survival due to human activities across their distribution range in Africa. Little is known about habitat suitability of the Nigeria–Cameroon chimpanzee [ Pan troglodytes ellioti (Matschie, 1914)], particularly for populations inhabiting forest reserves in North-West Cameroon. To address this knowledge gap, we employed a common species distribution model (MaxEnt) to map and predict suitable habitats for the Nigeria–Cameroon chimpanzee in Kom-Wum Forest Reserve, North-West Cameroon, based on environmental factors that potentially affect habitat suitability. We related these environmental factors to a dataset of chimpanzee occurrence points recorded during line transect and reconnaissance (recce) surveys in the forest reserve and surrounding forests. Up to 91% of the study area is unsuitable for chimpanzees. Suitable habitats only represented 9% of the study area, with a high proportion of highly suitable habitats located outside the forest reserve. Elevation, secondary forests density, distance to villages and primary forests density were the most important predictors of habitat suitability for the Nigeria–Cameroon chimpanzee. The probability of chimpanzee occurrence increased with elevation, secondary forest density and distance from villages and roads. Our study provides evidence that suitable chimpanzee habitat in the reserve is degraded, suggesting that efforts to maintain protected areas are insufficient. The reserve management plan needs to be improved to conserve the remaining suitable habitat and to avoid local extinction of this endangered subspecies.Rufford Foundation http://dx.doi.org/10.13039/100007463International Foundation for Science http://dx.doi.org/10.13039/100004413Brandenburgische TU Cottbus-Senftenber
Comparison of immunomodulatory properties of cystatins in free-living and parasitic nematodes
No full textDeckblatt, Inhaltsverzeichnis, Abkürzungsverzeichnis, Literatur,
Publikationen, Danksagung, Lebenslauf, Erklärung
Zusammenfassung
summary
Einleitung
Ziel der Arbeit
Ergebnisse Teil 1
Ergebnisse Teil 2
Diskussion
Schlussfolgerung
Methoden
MaterialParasitische Nematoden (Fadenwürmer) beeinflussen das Immunsystem ihres
Wirtes, um ihn möglichst lange ausnutzen zu können. Um diese Immunmodulation
zu verstehen, ist eine Untersuchung der Mechanismen auf molekularer Ebene
notwendig. Meine Arbeit versucht, in einem vergleichenden Ansatz die bei
parasitären Nematoden evolvierten Mechanismen der Immunmodulation
herauszuarbeiten, indem von den Würmern ausgeschiedene Proteinase-inhibitoren
(Cystatine) untersucht werden. Cysele1 und Cysele2, Cystatine des
freilebenden, nichtparasitären Nematoden Caenorhabditis elegans, wurden
kloniert, exprimiert und hinsichtlich ihres Einflusses auf die zelluläre
Immunantwort von Mäusen und Menschen untersucht. Als Vergleich dienten bereits
beschriebene rekombinante Cystatine parasitärer Nematoden, Av17 (Hartmann et
al., 1997), ein Cystatin der Nagetierfilarie Acanthocheilonema viteae, sowie
Ov17 (Schönemeyer et al., 2001), ein Cystatin der humanpathogenen Filarie
Onchocerca volvulus. Der markanteste Unterschied in der Wirkung der Cystatine
bestand in ihrem Einfluß auf die Proliferation von T-Lymphozyten.
Filariencystatine supprimierten signifikant die Proliferation polyklonal und
antigenspezifisch stimulierter Mausmilzzellen und humaner PBMC. Demgegenüber
hatten die C. elegans-Cystatine keinen bzw. einen geringen Einfluß auf diese
Formen der Proliferation. Auf der Suche nach den Ursachen für diesen
Unterschied wurden verschiedene Vorgänge betrachtet. Humane Cathepsine, die an
einer Antigenprozessierung und ?präsentation durch APC beteiligt sind, wurden
durch die untersuchten Cystatine unterschiedlich stark inhibiert (besonders
Cathepsin S und B). Dafür sind wahrscheinlich Mutationen in der
Inhibitionsdomäne der Proteine verantwortlich. Das Zytokinmuster polyklonal
stimulierter, humaner PBMC und somit die Regulation von Immunantworten wurde
durch Filarien- und C. elegans-Cystatine ebenfalls unterschiedlich beeinflußt.
Während Filariencystatine die Produktion des entzündungshemmenden Zytokins
IL-10 induzierten, wurden unter dem Einfluß der C. elegans-Cystatine verstärkt
die entzündungsfördernden Zytokine IFN-g und IL-12 gebildet. Die Produktion
von NO durch murine Peritonealmakrophagen wurde durch Filarien- bzw. C.
elegans-Cystatine ähnlich stark stimuliert. Meine Daten zeigen, daß einige
immunmodulatorische Effekte von Filariencystatinen sich klar von den Effekten
der C. elegans-Cystatine unterscheiden. Damit ist zu vermuten, daß Filarien im
Lauf der Evolution bestimmte, auch schon bei freilebenden Formen vorhandene
Proteine so modifiziert haben, daß diese die Immunantwort ihres Wirtes gezielt
beeinflussen und eine spezifische Toleranz des Parasiten herbeiführen.Parasitic nematodes modulate the immune systems of their hosts to exploit them
as long as possible. In an effort to understand the molecular mechanisms
involved in this immunomodulation, I examined the role of nematode-encoded
secreted protease inhibitors (cystatins). Cysele1 and Cysele2, cystatins of
the free-living, non-parasitic nematode Caenorhabditis elegans were cloned,
expressed and investigated for their impact on mice and human cellular immune
responses. For comparision, previously described recombinant cystatins of
parasitic nematodes were used: Av17 (Hartmann et al., 1997), a cystatin of the
rodent filarial pathogen Acanthocheilonema viteae; and Ov17 (Schönemeyer et
al., 2001), a cystatin of the human filarial pathogen Onchocerca volvulus. The
most striking difference in the effect of the cystatins was the impact on the
proliferation of T lymphocytes. Filarial cystatins strongly suppressed the
proliferation of polyclonally and antigen specific stimulated murine spleen
cells and human PBMC. In contrast, the C. elegans cystatins had little or no
effect on either type of proliferation. Different processes were investigated
to find the basis for these differences. Human cathepsins involved in antigen
processing and presentation by APC were differentially inhibited by the
cystatins examined (mostly cathepsin S and B). Mutations in the domain of
inhibition of the proteins are probably responsible. The pattern of cytokine
production by polyclonally stimulated human PBMC and therefore the regulation
of the immune response were differentially effected by filarial and C. elegans
cystatins. Filarial cystatin induced the production of the antiinflammatory
cytokine IL-10 whereas C. elegans cystatins induced the production of the
proinflammatory cytokines IFN-g and IL-12. The production of NO by murine
peritoneal macrophages was stimulated by both the filarial and C. elegans
cystatins. My data show, that certain immunomodulatory effects of filarial
cystatins are clearly different from the effects of the C. elegans cystatins.
We propose that during evolution of filarial parasites selection for
modifications in proteins pre-existing in free-living nematodes occured which
targeted the immune response of their hosts resulting in reduced immune
clearance
Profiles of criteria and non-criteria anti-phospholipid autoantibodies are associated with clinical phenotypes of the antiphospholipid syndrome
No full textSpecific anti-phospholipids antibodies (aPLs) are used as classification criteria of the antiphospholipid syndrome (APS). These aPLs, although essential for diagnosis, do not predict disease phenotypes, which may require specific therapies. Non-criteria aPLs are rarely evaluated and their role is yet to be defined. In the current study, we aimed to examine the association between criteria and non-criteria aPLs and APS phenotypes
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No full textExPEC-typical virulence associated genes correlate with successful colonization by intestinal E. coli in a piglet group
No full textZoonotic bacterial and parasitic intestinal pathogens in foxes, raccoons and other predators from eastern Germany.
No full textIn this study, we investigated faecal specimens from legally hunted and road-killed red foxes, raccoons, raccoon dogs, badgers and martens in Germany for parasites and selected zoonotic bacteria. We found that Baylisascaris procyonis, a zoonotic parasite of raccoons, had spread to northeastern Germany, an area previously presumed to be free of this parasite. We detected various pathogenic bacterial species from the genera Listeria, Clostridium (including baratii), Yersinia and Salmonella, which were analysed using whole-genome sequencing. One isolate of Yersinia enterocolitica contained a virulence plasmid. The Salmonella Cholerasuis isolate encoded an aminoglycoside resistance gene and a parC point mutation, conferring resistance to ciprofloxacin. We also found tetracycline resistance genes in Paeniclostridium sordellii and Clostridium baratii. Phylogenetic analyses revealed that the isolates were polyclonal, indicating the absence of specific wildlife-adapted clones. Predators, which scavenge from various sources including human settlements, acquire and spread zoonotic pathogens. Therefore, their role should not be overlooked in the One Health context
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