Target genes for virulence assessment of Escherichia coli isolates from water, food and the environment

The widespread species Escherichia coli includes a broad variety of different types, ranging from highly pathogenic strains causing worldwide outbreaks of severe disease to avirulent isolates which are part of the normal intestinal flora or which are well characterized and safe laboratory strains. The pathogenicity of a given E. coli strain is mainly determined by specific virulence factors which include adhesins, invasins, toxins and capsule. They are often organized in large genetic blocks either on the chromosome (‘pathogenicity islands'), on large plasmids or on phages and can be transmitted horizontally between strains. In this review we summarize the current knowledge of the virulence attributes which determine the pathogenic potential of E. coli strains and the methodology available to assess the virulence of E. coli isolates. We also focus on a recently developed procedure based on a broad-range detection system for E. coli-specific virulence genes that makes it possible to determine the potential pathogenicity and its nature in E. coli strains from various sources. This makes it possible to determine the pathotype of E. coli strains in medical diagnostics, to assess the virulence and health risks of E. coli contaminating water, food and the environment and to study potential reservoirs of virulence genes which might contribute to the emergence of new forms of pathogenic E. col

Mannheimia indoligenes sp. nov., proposed for clade V organisms of Mannheimia

A set of 25 strains belonging to clade V of Mannheimia mainly isolated from cattle was investigated and is proposed to represent Mannheimia indoligenes sp. nov. The species can be separated from the other validly published species of the genus by pheno-and genotype. Only indole separates M. indoligenes and Mannheimia varigena while two to seven characters separate M. indoligenes from other species of Mannheimia. Thirteen strains belonging to biogroups 6, 7, 8C, 9, 10, 12 and UG5 formed a monophyletic group based on 16S rRNA gene sequence comparisons with 98–100% similarity. Eight of these strains were further included in the whole genome comparison. Digital DNA–DNA hybridization showed that the similarities between the suggested type strain M14.4T and the other strains of M. indoligenes were 62.9% or higher. The average nucleotide identity was 95.5% or higher between M14.4T and the other strains of the species. The rpoB gene sequence similarity was 95–100% within M. indoligenes. MALDI-TOF allowed a clear separation from other Mannheimia species further supporting classification as a novel species and making it the diagnostic identification tool of choice for M. indoligenes. The type strain is M14.4T (=CCUG 77347T=DSM 116804T) isolated from a cattle tongue in Scotland.</p

Nachfrage nach Öko-Lebensmitteln: Ergebnisse einer repräsentativen Verbraucherstudie

Der erste deutsche BSE-Fall im November 2000 hat zu heftigen Reaktionen der Verbraucher bei der Nachfrage nach Lebensmitteln geführt. Der Rindfleischkonsum brach im Dezember 2000 und Januar 2001 um fast 70 % im Vergleich zu den Vorjahresmonaten ein, während Geflügelfleisch, Fisch, Gemüse und andere Beilagen deutlich in der Verbrauchergunst stiegen. Auch der Markt für ökologische Lebensmittel profitierte deutlich von der deutschen BSE-Krise. Vor diesem Hintergrund stellte sich die Frage, ob die genannten Veränderungen möglicherweise Ausdruck eines veränderten Verbraucherbewusstseins gegenüber Lebensmitteln – insbesondere gegenüber ökologisch erzeugten Produkten – sind. Die Beantwortung dieser und einer Reihe weiterer Fragen waren leitend für die Untersuchung

Nachfrage nach Öko-Lebensmitteln: Veränderung durch BSE?

Der erste deutsche BSE-Fall im November 2000 hat zu starken Veränderungen in der Lebensmittelnachfrage geführt. Der Rindfleischkonsum brach im Dezember 2000 und Januar 2001 um fast 70 Prozent im Vergleich zu den Vorjahresmonaten ein, während vor allem Geflügelfleisch, Fisch und Gemüse deutlich in der Verbrauchergunst stiegen (GfK, 2001). Auch der Markt für ökologisch erzeugte Lebensmittel profitierte von der deutschen BSE-Krise: Der Bundesverband Naturkost Naturwaren (BNN) meldete für das erste Halbjahr 2001 ein Umsatzwachstum von 36,5 Prozent gegenüber dem Vorjahreszeitraum (Rippin, 2002). Auch die Daten des ACNielsen Handelspanels zum Absatz von Bio-Frischmilch über den konventionellen Lebensmitteleinzelhandel (LEH) wiesen für Anfang 2001 ungewöhnlich hohe Wachstumsraten auf (Rippin, 2001). Handelt es sich bei diesen Beobachtungen möglicherweise um Anzeichen für ein verändertes Verbraucherbewusstsein gegenüber Lebensmitteln und insbesondere gegenüber ökologisch erzeugten Produkten? Diese und eine Reihe weiterer Fragen wurden in einer repräsentativen Verbraucherstudie der Universität Hamburg untersucht, bundesweit waren dazu 2 000 Personen im Alter von 18-75 Jahren im September 2001 befragt worden

Ovine footrot: A review of current knowledge

Footrot is a contagious foot disease mainly affecting sheep. It is caused by the Gram-negative anaerobic bacterium Dichelobacter nodosus. Warm, wet environmental conditions favour development of footrot, and under perfect conditions, it takes just 2–3 weeks from infection to manifestation of clinical signs. Affected sheep show lameness of various degrees and often graze while resting on their carpi. Local clinical signs vary in severity and extent from interdigital inflammation (benign footrot) to underrunning of the complete horn shoe in advanced stages of virulent footrot. Laboratory diagnosis ideally involves collection of four-foot interdigital swab samples followed by competitive real time PCR, allowing for detection of the presence of D. nodosus and differentiation between benign and virulent strains. Laboratory-based diagnostics at the flock level based on risk-based sampling and pooling of interdigital swab samples are recommended. The list of treatment options of individual sheep includes careful removal of the loose undermined horn, local or systemic administration of antimicrobials, systemic administration of non-steroidal anti-inflammatories (NSAIDs) and disinfectant footbathing. Strategies for control at the flock level are manifold and depend on the environmental conditions and the procedures traditionally implemented by the respective country. Generally, measures consist of treatment/culling of infected sheep, vaccination and prevention of reinfection of disease-free flocks. Gaining deeper insight into the beneficial effects of NSAIDs, screening for eco-friendly footbath solutions, developing better vaccines, including the development of a robust, reproducible infection model and elucidation of protective immune responses, as well as the elaboration of effective awareness training programs for sheep farmers, are relevant research gaps

Speciating Campylobacter jejuni and Campylobacter coli isolates from poultry and humans using six PCR-based assays

Six previously published polymerase chain reaction (PCR) assays each targeting different genes were used to speciate 116 isolates previously identified as Campylobacter jejuni using routine microbiological techniques. Of the 116 isolates, 84 were of poultry origin and 32 of human origin. The six PCR assays confirmed the species identities of 31 of 32 (97%) human isolates and 56 of 84 (67%) poultry isolates as C. jejuni. Twenty eight of 84 (33%) poultry isolates were identified as Campylobacter coli and the remaining human isolate was tentatively identified as Campylobacter upsaliensis based on the degree of similarity of 16S rRNA gene sequences. Four of six published PCR assays showed 100% concordance in their ability to speciate 113 of the 116 (97.4%) isolates; two assays failed to generate a PCR product with four to 10 isolates. A C. coli-specific PCR identified all 28 hippuricase gene (hipO)-negative poultry isolates as C. coli although three isolates confirmed to be C. jejuni by the remaining five assays were also positive in this assay. A PCR-restriction fragment length polymorphism assay based on the 16S rRNA gene was developed, which contrary to the results of the six PCR-based assays, identified 28 of 29 hipO-negative isolates as C. jejuni. DNA sequence analysis of 16S rRNA genes from four hipO-negative poultry isolates showed they were almost identical to the C. jejuni type strain 16S rRNA sequences ATCC43431 and ATCC33560 indicating that assays reliant on 16S rRNA sequence may not be suitable for the differentiation of these two specie

Field validation of an antibiotic-free hoof spray to effectively treat ovine footrot by eliminating virulent Dichelobacter nodosus.

Ovine footrot caused by Dichelobacter nodosus is a highly contagious hoof disease negatively impacting animal welfare and causing major economic losses to the sheep industry. Bactericidal footbaths have shown to be an efficient treatment option and will be used in the national footrot control program in Switzerland. However, the application of footbaths is laborious and economically not sound for small flock holders. We therefore tested in a field study the Intra Repiderma spray for its applicability and efficacy to treat ovine footrot. Ten independent flocks fulfilling defined parameters (e.g. clinical signs, positive for D. nodosus, flock size) could be identified and were included in the study. Farms were visited weekly to fortnightly and clinical scores and swabs for D. nodosus real-time (rt)PCR were taken. Treatment with the Intra Repiderma spray was started after initial claw trimming at the very first visit and was carried out three times within a week. Clearly visible clinical improvement was evident after one week of treatment. Virulent D. nodosus amounts on feet declined constantly during treatment which was continued until all sheep of a flock tested rtPCR-negative (1-10 weeks). Results indicate that a highly effective improvement of clinical signs and complete elimination of virulent D. nodosus can be achieved with the spray treatment. Therefore, it is a valuable alternative to cumbersome footbaths especially for small flocks. A sustainable control of footrot and its pathogen in a successfully treated flock can be maintained by strict biosecurity measures and continued treatment as far as necessary

Parameter Identification by Deep Learning of a Material Model for Granular Media

Classical physical modelling with associated numerical simulation (model-based), and prognostic methods based on the analysis of large amounts of data (data-driven) are the two most common methods used for the mapping of complex physical processes. In recent years, the efficient combination of these approaches has become increasingly important. Continuum mechanics in the core consists of conservation equations that -- in addition to the always necessary specification of the process conditions -- can be supplemented by phenomenological material models. The latter are an idealized image of the specific material behavior that can be determined experimentally, empirically, and based on a wealth of expert knowledge. The more complex the material, the more difficult the calibration is. This situation forms the starting point for this work's hybrid data-driven and model-based approach for mapping a complex physical process in continuum mechanics. Specifically, we use data generated from a classical physical model by the MESHFREE software to train a Principal Component Analysis-based neural network (PCA-NN) for the task of parameter identification of the material model parameters. The obtained results highlight the potential of deep-learning-based hybrid models for determining parameters, which are the key to characterizing materials occurring naturally, and their use in industrial applications (e.g. the interaction of vehicles with sand).Comment: arXiv admin note: text overlap with arXiv:2212.0313

Innovationen bei der Vermittlung kommunikativer Kompetenzen in der Medizinerausbildung [an der Medizinischen Fakultät der Universität Rostock]: Eine Querschnittsstudie vor dem Hintergrund des Bologna-Prozesses

Die Arbeit stellt die Frage nach den inhaltlichen, methodischen, organisatorischen und strukturellen Details von Lehrveranstaltungen zur Steigerung der kommmunikativen Kompetenzen von Medizinstudierenden. Das RoMeLeTz (Rostocker Mediziner- und Lehrertrainingszentrum) wird als eine realistische Möglichkeit für eine solche Organisationsform aus einer Datenanalyse von fast 700 TN an einer empirischen Studie herausgestellt. Kliniker, Vorkliniker und Ärzte wurden repräsentativ befragt und rund 28.000 Daten erfasst sowie ausgewertet

Digital Averaging Phasemeter for Heterodyne Interferometry

A digital averaging phasemeter has been built for measuring the difference between the phases of the unknown and reference heterodyne signals in a heterodyne laser interferometer. This phasemeter performs well enough to enable interferometric measurements of distance with accuracy of the order of 100 pm and with the ability to track distance as it changes at a speed of as much as 50 cm/s. This phasemeter is unique in that it is a single, integral system capable of performing three major functions that, heretofore, have been performed by separate systems: (1) measurement of the fractional-cycle phase difference, (2) counting of multiple cycles of phase change, and (3) averaging of phase measurements over multiple cycles for improved resolution. This phasemeter also offers the advantage of making repeated measurements at a high rate: the phase is measured on every heterodyne cycle. Thus, for example, in measuring the relative phase of two signals having a heterodyne frequency of 10 kHz, the phasemeter would accumulate 10,000 measurements per second. At this high measurement rate, an accurate average phase determination can be made more quickly than is possible at a lower rate