Analysis of the cause for Salmonella spread from bacteriological sampling of stall surroundings

The cause for Salmonella spread and reinfection was tried to be analysed and identified from bacteriological sampling of stall surroundings in 50 fattening farms and closed farms that had shown an increased prevalence of Salmonella detected by meat-juice-examination. In the bacteriological examination 388 samples of the stall surroundings were analysed. Only in 5 (3x rodent droppings, 1x stall dust and 1x animal feed) samples Salmonelfa Typhimurium was isolated. Generally, it was impossible to ascertain the reasons for Salmonella spread and reinfection in a farm with a positive meat-juice sample based on pathogen identification

Evaluation of the tolerability of the Salmonella Typhimurium live vaccine Salmoporc® for oral administration in three day old piglets

Vaccination against Salmonella is a measure to reduce salmonella disease in pigs. In this study a S. Typhimurium live vaccine (Salmoporc®, lmpfstoffwerk Dessau-Tornau, Rosslau, Germany) was applied to 3 day old conventional piglets in order to investigate safety and persistence of the vaccine strain in different tissues. The results indicate that an early vaccination against Salmonella shall be deemed to be safe

Production of highly oxygenated organic molecules (HOMs) from trace contaminants during isoprene oxidation

During nucleation studies from pure isoprene oxidation in the CLOUD chamber at the European Organization for Nuclear Research (CERN) we observed unexpected ion signals at m∕z&thinsp; = &thinsp;137.133 (C10H17+) and m∕z&thinsp; = &thinsp;81.070 (C6H9+) with the recently developed proton-transfer-reaction time-of-flight (PTR3-TOF) mass spectrometer instrument. The mass-to-charge ratios of these ion signals typically correspond to protonated monoterpenes and their main fragment. We identified two origins of these signals: first secondary association reactions of protonated isoprene with isoprene within the PTR3-TOF reaction chamber and secondly [4+2] cycloaddition (Diels–Alder) of isoprene inside the gas bottle which presumably forms the favored monoterpenes limonene and sylvestrene, as known from literature. Under our PTR3-TOF conditions used in 2016 an amount (relative to isoprene) of 2&thinsp;% is formed within the PTR3-TOF reaction chamber and 1&thinsp;% is already present in the gas bottle. The presence of unwanted cycloaddition products in the CLOUD chamber impacts the nucleation studies by creating ozonolysis products as the corresponding monoterpenes and is responsible for the majority of the observed highly oxygenated organic molecules (HOMs), which in turn leads to a significant overestimation of both the nucleation rate and the growth rate. In order to study new particle formation (NPF) from pure isoprene oxidation under relevant atmospheric conditions, it is important to improve and assure the quality and purity of the precursor isoprene. This was successfully achieved by cryogenically trapping lower-volatility compounds such as monoterpenes before isoprene was introduced into the CLOUD chamber.</p

Bacteria in milk from anterior and posterior mammary glands in sows affected and unaffected by postpartum dysgalactia syndrome (PPDS)

<p>Abstract</p> <p>Background</p> <p>The performance of piglet weight gain is strongly dependent on the sow's ability to meet the demand for adequate milk. Postparturient disorders, especially those subsumed under the term postpartum dysgalactia syndrome (PPDS), can alter or reduce the milk production sensitively, resulting in starving piglets. The aim of this study was to gather further information about the prevalence of different bacterial species in the anterior and posterior mammary glands of sows with respect to the clinical appearance of PPDS.</p> <p>Methods</p> <p>In this study, the health status of 56 sows after farrowing was determined with special regard to mastitis and dysgalactia. Pooled milk samples from anterior and posterior glands were taken from both affected and non-affected animals and analysed bacteriologically for the presence of a wide spectrum of different pathogens.</p> <p>Results</p> <p>Mainly <it>Escherichia coli</it>, staphylococci and streptococci were detected in high percentages but without significant differences in healthy and diseased animals and anterior and posterior glands. However, the large percentages of coliform bacteria suggested a transmission route via faecal contamination.</p> <p>Conclusion</p> <p>In this study, the prevalence of different bacteria in anterior and posterior glands in PPDS positive and negative sows was analysed. No significant differences in bacteria of healthy and diseased sows were assessed. Therefore, the development of clinical PPDS and actual infection seems to be largely dependant on individual resistance in single sows.</p

Global atmospheric particle formation from CERN CLOUD measurements

Fundamental questions remain about the origin of newly formed atmospheric aerosol particles because data from laboratory measurements have been insufficient to build global models. In contrast, gas-phase chemistry models have been based on laboratory kinetics measurements for decades. Here we build a global model of aerosol formation using extensive laboratory-measured nucleation rates involving sulfuric acid, ammonia, ions and organic compounds. The simulations and a comparison with atmospheric observations show that nearly all nucleation throughout the present-day atmosphere involves ammonia or biogenic organic compounds in addition to sulfuric acid. A significant fraction of nucleation involves ions, but the relatively weak dependence on ion concentrations indicates that for the processes studied variations in cosmic ray intensity do not significantly affect climate via nucleation in the present-day atmosphere

Experimental particle formation rates spanning tropospheric sulfuric acid and ammonia abundances, ion production rates, and temperatures

Binary nucleation of sulfuric acid and water as well as ternary nucleation involving ammonia are thought to be the dominant processes responsible for new particle formation (NPF) in the cold temperatures of the middle and upper troposphere. Ions are also thought to be important for particle nucleation in these regions. However, global models presently lack experimentally measured NPF rates under controlled laboratory conditions and so at present must rely on theoretical or empirical parameterizations. Here with data obtained in the European Organization for Nuclear Research CLOUD (Cosmics Leaving OUtdoor Droplets) chamber, we present the first experimental survey of NPF rates spanning free tropospheric conditions. The conditions during nucleation cover a temperature range from 208 to 298K, sulfuric acid concentrations between 5x10(5) and 1x10(9)cm(-3), and ammonia mixing ratios from zero added ammonia, i.e., nominally pure binary, to a maximum of -1400 parts per trillion by volume (pptv). We performed nucleation studies under pure neutral conditions with zero ions being present in the chamber and at ionization rates of up to 75ion pairs cm(-3)s(-1) to study neutral and ion-induced nucleation. We found that the contribution from ion-induced nucleation is small at temperatures between 208 and 248K when ammonia is present at several pptv or higher. However, the presence of charges significantly enhances the nucleation rates, especially at 248K with zero added ammonia, and for higher temperatures independent of NH3 levels. We compare these experimental data with calculated cluster formation rates from the Atmospheric Cluster Dynamics Code with cluster evaporation rates obtained from quantum chemistry.Peer reviewe

The role of low-volatility organic compounds in initial particle growth in the atmosphere

About half of present-day cloud condensation nuclei originate from atmospheric nucleation, frequently appearing as a burst of new particles near midday1. Atmospheric observations show that the growth rate of new particles often accelerates when the diameter of the particles is between one and ten nanometres2, 3. In this critical size range, new particles are most likely to be lost by coagulation with pre-existing particles4, thereby failing to form new cloud condensation nuclei that are typically 50 to 100 nanometres across. Sulfuric acid vapour is often involved in nucleation but is too scarce to explain most subsequent growth5, 6, leaving organic vapours as the most plausible alternative, at least in the planetary boundary layer7, 8, 9, 10. Although recent studies11, 12, 13 predict that low-volatility organic vapours contribute during initial growth, direct evidence has been lacking. The accelerating growth may result from increased photolytic production of condensable organic species in the afternoon2, and the presence of a possible Kelvin (curvature) effect, which inhibits organic vapour condensation on the smallest particles (the nano-Köhler theory)2, 14, has so far remained ambiguous. Here we present experiments performed in a large chamber under atmospheric conditions that investigate the role of organic vapours in the initial growth of nucleated organic particles in the absence of inorganic acids and bases such as sulfuric acid or ammonia and amines, respectively. Using data from the same set of experiments, it has been shown15 that organic vapours alone can drive nucleation. We focus on the growth of nucleated particles and find that the organic vapours that drive initial growth have extremely low volatilities (saturation concentration less than 10−4.5 micrograms per cubic metre). As the particles increase in size and the Kelvin barrier falls, subsequent growth is primarily due to more abundant organic vapours of slightly higher volatility (saturation concentrations of 10−4.5 to 10−0.5 micrograms per cubic metre). We present a particle growth model that quantitatively reproduces our measurements. Furthermore, we implement a parameterization of the first steps of growth in a global aerosol model and find that concentrations of atmospheric cloud concentration nuclei can change substantially in response, that is, by up to 50 per cent in comparison with previously assumed growth rate parameterizations