Report on Salmonella isolates submitted to the German National Reference Laboratory for running analyses and tests on zoonoses (Salmonella) in the year 2009

The present report deals with Salmonella strains received at the German National Reference Laboratory for Salmonella (NRL-Salm) for routine diagnostic in the year 2009. Hence, the working group continues the previous report from Friedrich et al. (2010) about the documentation on the serovar distribution of Salmonella received at the NRL-Salm in the years 2004-2008. As in the recent years, most of the Salmonella strains originated from livestock and food. In the year 2009 the NRL-Salm received 4765 isolates, most of them (85,1 %) were routine diagnostic. Salmonella ser. Typhimurium, its monophasic variant S. enterica subspecies enterica serovar 1,4,[5],12:i:- and Salmonella ser. Enteritidis were the most prevalent serovars. The number of S. enterica subsp. enterica serovar 1,4,[5],12:i:- isolates increased in 2009, in comparison to the years 2004-2008, and became the second most prevalent serovar serotyped at the NRL-Salm.     

The cost of risk management and multifunctionality in forestry: a simulation approach for a case study area in Southeast Germany

Forest management faces growing uncertainty concerning environmental conditions and demand for ecosystem services. To help forest managers consider uncertainty, we applied a robust and multi-criteria approach to select the optimal composition of a forest enterprise from 12 stand types. In our simulation, the forest enterprise strives for either financial return or a multi-criteria forest management considering financial return, carbon storage and forest ecosystem stability. To quantify the influence of climate change on these decision criteria, we used the concept of analogous climate zones. Our results provide recommendations for long-term strategies for tree species selection in a Southeast German forest enterprise. The results show that considering both uncertainty and multifunctionality in forest management led to more diversified forest compositions. However, robust and multi-criteria optimisation required the forest enterprise to pay a premium in terms of lower income. Financial returns decreased when forest composition accounted for uncertainty or multiple objectives. We also found that adaptation measures could only partly financially compensate the effects of climate change. As the study is limited to two tree species, including additional tree species, variants of mixing proportions and further silvicultural strategies in the optimisation appears a promising avenue for future research.

     

Requirement of salicylic Acid for the induction of systemic acquired resistance

It has been proposed that salicylic acid acts as an endogenous signal responsible for inducing systemic acquired resistance in plants. The contribution of salicylic acid to systemic acquired resistance was investigated in transgenic tobacco plants harboring a bacterial gene encoding salicylate hydroxylase, which converts salicylic acid to catechol. Transgenic plants that express salicylate hydroxylase accumulated little or no salicylic acid and were defective in their ability to induce acquired resistance against tobacco mosaic virus. Thus, salicylic acid is essential for the development of systemic acquired resistance in tobacco.     

Teat canal closure in non-lactating heifers and its association with udder health in the consecutive lactation

Prevention of heifer mastitis is a key element in preventing mastitis. Since pathogenesis of heifer mastitis is not fully understood yet, combating it is arduous. The goal of this study was to examine whether the premature loss of the keratin plug of the teat canal represents an important risk factor for the development of heifer mastitis. 84 dairy heifers (German Holstein) from six high-yielding dairy herds in Northern Germany were examined between March 2005 and June 2006. Each quarter was examined clinically at least three times before calving. If the teat canal of a quarter was open, secretion samples were collected for bacteriological analysis. After calving, four quarter samples were collected during the first lactation. A rapid increase of the proportion of open teat canals was detected in the preparturition period. No teat canals were open till 80 days before parturition, while 60% of the teat canals were open at 60 days before parturition. A time-scheduled infection pattern was observed: during the days 90-61, 60-31, and 30-0 before calving, skin inhabitants (coagulase-negative staphylococci, coryneform bacteria), cow-related, and environment-related microorganisms prevailed, respectively. A total of 77% of intramammary infections encountered at parturition had established previously. No significant association between the duration of open teat canals before calving and the udder health post partum was found. However, the incidence of clinical mastitis during first lactation was influenced largely by the duration of infection ante partum and the mastitis pathogen involved. This study shows that a high proportion of teat canals already opens several months before calving and that opening of the teat canal before calving is an important factor in the aetiology of heifer mastitis.     

Rapid testing and quantification of Salmonella in ileocaecal lymph nodes of Austrian pigs slaughtered for consumption

Traditionally, quantitative microbial risk assessment (QMRA) is based on culture-dependent technologies. However, molecular quantification could forge additional, detailed information. A prerequisite of quantitative real-time PCR in animal science is a tissue preparation method where large volumes of tissue material can be reduced and particularly target cells can be concentrated. An easy-to-use sample preparation method for food (Matrix-Lysis) was recently adapted to tissues and now permits quantification of target cells from up to 5 g of organic matrix. The aim of this study was to examine the suitability of Matrix-Lysis for quantification of Salmonella in porcine ileocaecal lymph nodes (ICLNs). After demonstrating constant recovery rates, ICLNs from 540 pigs were examined for Salmonella spp. with Matrix-Lysis. Samples were also analysed using ISO 6579:2002, a combined enrichment/qPCR method and a lateral flow test. It could be shown that qPCR coupled with Matrix-Lysis can contribute to QMRA in food safety by enabling reproducible quantitative data, even at low contamination rates.     

Effects on boar semen quality after infection with porcine reproductive and respiratory syndrome virus: a case report

The effect of porcine reproductive and respiratory syndrome virus (PRRSV) on semen quality was examined in a group of 11 spontaneously infected boars in a commercial boar stud. Semen samples were collected 4 weeks prior to 4 weeks post-infection (wpi). Infection with PRRSV of the European genotype subtype 1 (EU-1) was verified by specific quantitative real-time polymerase chain reaction (RT-PCR) in 36% of the serum samples. All boars seroconverted before 4 wpi and remained in normal condition throughout the study. Comparison of the percentage of morphologically intact spermatozoa revealed an increase of acrosome-defective spermatozoa (P = 0.012) between −4 and 4 wpi. Significant deleterious effects on semen quality were detected for membrane integrity when semen had been stored for 2 days after sampling. Analysis of sperm subpopulations in a thermoresistance test on day 7 after sampling revealed alterations in the percentage of circular, progressively motile spermatozoa (P = 0.013), in the percentage of non-linear, progressively motile spermatozoa (P = 0.01), and on the amplitude of lateral sperm head displacement (P = 0.047). There was no difference in the incidence of mitochondrially active spermatozoa (P = 0.075). Investigation of routine production data between pre- and post-infection status showed no differences on ejaculate volume (P = 0.417), sperm concentration (P = 0.788), and percentage of motile spermatozoa (P = 0.321). This case report provides insights into a potential control strategy for PRRSV outbreaks in boar studs.     

The dose dependence of 15N-incorporation in organ proteins of newborn rats after pulse labeling with different tracers

A short-chain 15N-peptide mixture characterized by an average chain length of 2.3 was obtained when 15N-labeled yeast protein has hydrolyzed enzymatically by thermitase from Thermoactinomyces vulgaris. Fifteen newborn Wistar-rats were given a single pulse of [15N]glycine. [15N]H4Cl and [15N]yeast protein-thermitasehydrolysate (YPTH) in a dosage of 50 mg 15N excess kg-1 by gastric tube. In comparison with [15N]glycine the 15N-incorporation rates of brain, muscle and liver were approximately 150% higher after [15N]YPTH-application. Uniform labeling, high 15N-enrichment, almost complete absorption, avoidance of imbalances and the low price make this tracer substance superior to other tracers conventionally used for organ labeling.