Stereologic analysis of tibial-plateau cartilage and femoral cancellous bone in guinea pigs with spontaneous osteoarthritis

Two strains of guinea pig develop spontaneous osteoarthritis of the knee. Although the disease evolves at different rates in the two strains, it is not known whether these differences are reflected in the structure of the cartilage and cancellous bone.

Evaluation of multimeric tyrosine-O-sulfate as a cytoprotectant in an in vivo model of acute myocardial infarction in pigs

Intracoronary administration of glycosaminoglycan analogs, including the complement inhibitor dextran sulfate, attenuates myocardial ischemia/reperfusion injury (I/R injury). However, dextran sulfate has a distinct anticoagulatory effect, possibly limiting its use in specific situations in vivo. We therefore developed multimeric tyrosine sulfate (sTyr-PAA), a novel, minimally anticoagulatory, fully synthetic non-carbohydrate-containing polyacrylamide conjugate, for in vivo testing in an acute closed-chest porcine model of acute myocardial infarction.

A novel isolation method of Brucella species and molecular tracking of Brucella suis biovar 2 in domestic and wild animals

Brucella suis biovar 2 is the most common aetiological agent of porcine brucellosis in Europe. B. suis biovar 2 is considered to have low zoonotic potential, but is a causative agent of reproductive losses in pigs, and it is thus economically important. The multilocus variable-number of tandem repeats genotyping analysis of 16 loci (MLVA-16) has proven to be highly discriminatory and is the most suitable assay for simultaneously identifying B. suis and tracking infections. The aim of this study was to investigate the relatedness between isolates of B. suis biovar 2 obtained during a brucellosis outbreak in domestic pigs and isolates from wild boars and hares collected from proximal or remote geographical areas by MLVA-16. A cluster analysis of the MLVA-16 data revealed that most of the isolates obtained from Switzerland clustered together, with the exception of one isolate. The outbreak isolates constituted a unique subcluster (with a genetic similarity >93.8%) distinct from that of the isolates obtained from wild animals, suggesting that direct transmission of the bacterium from wild boars to domestic pigs did not occur in this outbreak. To obtain a representative number of isolates for MLVA-16, alternative methods of Brucella spp. isolation from tissue samples were compared with conventional direct cultivation on a Brucella-selective agar. We observed an enhanced sensitivity when mechanical homogenisation was followed by host cell lysis prior to cultivation on the Brucella-selective agar. This work demonstrates that MLVA-16 is an excellent tool for both monitoring brucellosis and investigating outbreaks. Additionally, we present efficient alternatives for the isolation of Brucella spp.

Prevalence and genotypes of Toxoplasma gondii in feline faeces (oocysts) and meat from sheep, cattle and pigs in Switzerland

The protozoan parasite Toxoplasma gondii infects almost all warm blooded animal species including humans, and is one of the most prevalent zoonotic parasites worldwide. Post-natal infection in humans is acquired through oral uptake of sporulated T. gondii oocysts or by ingestion of parasite tissue cysts upon consumption of raw or undercooked meat. This study was undertaken to determine the prevalence of oocyst-shedding by cats and to assess the level of infection with T. gondii in meat-producing animals in Switzerland via detection of genomic DNA (gDNA) in muscle samples. In total, 252 cats (44 stray cats, 171 pet cats, 37 cats with gastrointestinal disorders) were analysed coproscopically, and subsequently species-specific identification of T. gondii oocysts was achieved by Polymerase Chain Reaction (PCR). Furthermore, diaphragm samples of 270 domestic pigs (120 adults, 50 finishing, and 100 free-range animals), 150 wild boar, 250 sheep (150 adults and 100 lambs) and 406 cattle (47 calves, 129 heifers, 100 bulls, and 130 adult cows) were investigated by T. gondii-specific real-time PCR. For the first time in Switzerland, PCR-positive samples were subsequently genotyped using nine PCR-restriction fragment length polymorphism (PCR-RFLP) loci (SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico) for analysis. Only one of the cats shed T. gondii oocysts, corresponding to a T. gondii prevalence of 0.4% (95% CI: 0.0-2.2%). In meat-producing animals, gDNA prevalence was lowest in wild boar (0.7%; 95% CI: 0.0-3.7%), followed by sheep (2.0%; 95% CI: 0.1-4.6%) and pigs (2.2%; 95% CI: 0.8-4.8%). The highest prevalence was found in cattle (4.7%; 95% CI: 2.8-7.2%), mainly due to the high prevalence of 29.8% in young calves. With regard to housing conditions, conventional fattening pigs and free-range pigs surprisingly exhibited the same prevalence (2.0%; 95% CI: 0.2-7.0%). Genotyping of oocysts shed by the cat showed T. gondii with clonal Type II alleles and the Apico I allele. T. gondii with clonal Type II alleles were also predominantly observed in sheep, while T. gondii with mixed or atypical allele combinations were very rare in sheep. In pigs and cattle however, genotyping of T. gondii was often incomplete. These findings suggested that cattle in Switzerland might be infected with Toxoplasma of the clonal Types I or III, atypical T. gondii or more than one clonal Type.

Relationship of porcine IGF2 imprinting status to DNA methylation at the H19 DMD and the IGF2 DMRs 1 and 2

BACKGROUND: Porcine IGF2 and the H19 genes are imprinted. The IGF2 is paternally expressed, while the H19 gene is maternally expressed. Extensive studies in mice established a boundary model indicating that the H19 differentially methylated domain (DMD) controls, upon binding with the CTCF protein, reciprocal imprinting of the IGF2 and the H19 genes. IGF2 transcription is tissue and development specific involving the use of 4 promoters. In the liver of adult Large White boars IGF2 is expressed from both parental alleles, whereas in skeletal muscle and kidney tissues we observed variable relaxation of IGF2 imprinting. We hypothesized that IGF2 expression from both paternal alleles and relaxation of IGF2 imprinting is reflected in differences in DNA methylation patterns at the H19 DMD and IGF2 differentially methylated regions 1 and 2 (DMR1 and DMR2). RESULTS: Bisulfite sequencing analysis did not show any differences in DNA methylation at the three porcine CTCF binding sites in the H19 DMD between liver, muscle and kidney tissues of adult pigs. A DNA methylation analysis using methyl-sensitive restriction endonuclease SacII and 'hot-stop' PCR gave consistent results with those from the bisulfite sequencing analysis. We found that porcine H19 DMD is distinctly differentially methylated, at least for the region formally confirmed by two SNPs, in liver, skeletal muscle and kidney of foetal, newborn and adult pigs, independent of the combined imprinting status of all IGF2 expressed transcripts. DNA methylation at CpG sites in DMR1 of foetal liver was significantly lower than in the adult liver due to the presence of hypomethylated molecules. An allele specific analysis was performed for IGF2 DMR2 using a SNP in the IGF2 3'-UTR. The maternal IGF2 DMR2 of foetal and newborn liver revealed a higher DNA methylation content compared to the respective paternal allele. CONCLUSIONS: Our results indicate that the IGF2 imprinting status is transcript-specific. Biallelic IGF2 expression in adult porcine liver and relaxation of IGF2 imprinting in porcine muscle were a common feature. These results were consistent with the IGF2 promoter P1 usage in adult liver and IGF2 promoter P2, P3 and P4 usages in muscle. The results showed further that bialellic IGF2 expression in liver and relaxation of imprinting in muscle and kidney were not associated with DNA methylation variation at and around at least one CTCF binding site in H19 DMD. The imprinting status in adult liver, muscle and kidney tissues were also not reflected in the methylation patterns of IGF2 DMRs 1 and 2.

Effects of isoflurane upon minimum alveolar concentration and cerebral cortex depression in pigs and goats: an interspecies comparison

This study compared the effects of isoflurane in pigs (n=10 Yorkshire-Landrace cross) and dairy goats (n=10) by evaluation of electroencephalographic (EEG) burst suppression thresholds (BST) in the cerebral cortex and minimum alveolar concentration (MAC) values in the spinal cord. The study also investigated whether individual MAC values can predict the effects of isoflurane on the cerebral cortex. MAC values and BST/MAC ratios were significantly different between species. Inhibition of movement by isoflurane may be less effective in pigs than in goats. No significant correlation was found between individual MAC and BST values, indicating that in single animals the individual MAC poorly reflects the cerebrocortical depressant effect of isoflurane in pigs and goats.

Establishing a European network for wildlife health surveillance

Surveillance of wildlife health in Europe remains informal and reporting wildlife diseases is not yet coordinated among countries. At a meeting in Brussels on 15 October 2009, delegates from 25 countries provided an overview of the current status of wildlife health surveillance in Europe. This showed that every year in Europe over 18,000 wild animals are examined as part of general surveillance programmes and over 50,000 wild animals are examined in the course of targeted surveillance. The participants at the Brussels meeting agreed to set up a European network for wildlife health surveillance. The goals of this network, which was established in February 2010, are to improve procedures for the rapid exchange of information, harmonise procedures for investigation and diagnosis of wildlife diseases, share relevant expertise, and provide training opportunities for wildlife health surveillance.

A study to demonstrate freedom of Trichinella spp. in domestic pigs in Switzerland

Trichinellosis is a food-borne zoonotic disease caused by the nematode Trichinella spp. Many omnivorous and carnivorous animal species can act as host for this parasite, including domestic pigs. To protect public health, it should be ensured that pork should not contain infective Trichinella larvae. Surveillance for Trichinella spp. can be done using direct (larval detection) and indirect (antibody detection) diagnostic techniques. The aim of this study was to demonstrate the absence of infection in Swiss domestic pigs. An ELISA was used as the initial screening test, and sera reacting in ELISA were further investigated using both a Western blot for serology and an artificial digestion test with 20 g of diaphragm tissue for larval detection. A total of 7412 adult pigs, 9973 finishing pigs and 2779 free-ranging pigs were tested. Samples from 17 (0.23%) adult pigs, 16 (0.16%) finishing pigs and nine (0.32%) free-ranging pigs were ELISA-positive, but all of these sera were subsequently negative by Western blot and by the artificial digestion method. Based on these findings, an absence of Trichinella infections in adult pigs (target prevalence 0.04%) and finishing pigs (target prevalence 0.03%) can be concluded. The results also demonstrated that the prevalence of Trichinella infections does not exceed 0.11% in free-ranging pigs, the group with the highest risk of exposure.

The increase of methicillin-resistant Staphylococcus aureus (MRSA) and the presence of an unusual sequence type ST49 in slaughter pigs in Switzerland

Background: In years past, methicillin-resistant S. aureus (MRSA) has been frequently detected in pigs in Europe, North America and Asia. Recent, yet sporadic studies have revealed a low occurrence of MRSA in Switzerland. In 2009, a monitoring survey of the prevalence and genetic diversity of methicillin-resistant S. aureus (MRSA) in slaughter pigs in Switzerland was conducted using methods recommended by the EU guidelines, and using a sampling strategy evenly distributed throughout the year and representative of the Swiss slaughter pig population. Monitoring should determine if the overall prevalence of MRSA in the entire country is increasing over the years and if specific multi-resistant MRSA clones are spreading over the country.;Results: In 2009, the nasal cavities of eight out of 405 randomly selected pigs were positive for MRSA, representing a prevalence of 2.0% (95% CI 0.9-3.9). The following year, 23 out of 392 pigs were positive for MRSA [5.9% prevalence (95% CI 3.8-8.7)]. Three multilocus sequence types (ST), four spa types and two types of staphylococcal cassette chromosome mec (SCCmec) elements were detected. The most frequent genotypes were ST398 (MLST)-(spa)t034-V (SCCmec) (n = 18) and ST49-t208-V (n = 7), followed by ST398-t011-V (n = 4), ST398-t1451-V (n = 1), and ST1-t2279-IVc (n = 1). The isolates displayed resistance to beta-lactams [mecA, (31/31); blaZ, (19/31)]; tetracycline [tet(M), (31/31); tet(K), (30/31)] (n = 31); macrolides and lincosamides [erm(C) (4/31) or erm(A) (18/31)] (n = 22); tiamulin [vga(A)v (9/31) or unknown mechanism (18/31)] (n = 27); trimethoprim [dfr(G) (18/31); spectinomycin [ant(9)-Ia (19/31) or unknown mechanism (3/31)] (n = 22); streptomycin [str(19/31)]; sulphamethoxazole (7/31) and ciprofloxacin (n = 1) (mechanisms not determined).;Conclusions: This study is the first to describe the presence of MRSA ST49 in slaughter pigs, and to demonstrate a significant and nearly three-fold increase of MRSA prevalence in pigs within two years. The presence of a specific clonal lineage of MRSA from Switzerland suggests that it has been selected in Swiss pig husbandry. Effective hygiene measures should be enhanced within the entire pig production chain to suppress the spread of these pathogens into the community.

Coping personality type and environmental enrichment affect aggression at weaning in pigs

This study investigated the effects of different environmental treatments and personality types on aggression at mixing of newly weaned domestic piglets. From birth to weaning, 16 litters were housed with their dams in either barren (B) or larger, substrate-enriched (E) environments. At 15 days old, piglets were classified as 'high' (HR) or low resistant' (LR) in a manual restraint test (backtest), which is thought to identify proactive (HR) and reactive (LR) stress coping strategies that may reflect different personality types. At 30 days old, 128 piglets were weaned, relocated and mixed into 32 pens comprising two HR and two LR unfamiliar pigs, balanced for sex and weaning weight. Eight B and eight E groups changed environmental condition whereas the others remained in the same type of environment. Number and duration of fights. fight outcomes and unilateral fighting were scored for 5 h post-mixing and skin lesions were counted before and 5 h, 1 day and 2 days after mixing. On the day following weaning, fighting and also exploratory and oral manipulative behaviours were measured for 6 h. Generalized Linear Mixed Model analyses suggested interactions between pre-weaning environment, post-weaning environment and personality type. Overall, pre-weaning E pigs had longer fights at weaning and mixing (P=0.01) and fought for longer on the next day (P=0.02) than pre-weaning B pigs, and inflicted more skin lesions (P=0.02). Post-weaning enrichment did not affect fighting at mixing but reduced the time spent fighting the next day (P=0.03). Personality had subtle and environment-dependent effects on fighting, and influenced the "structure" rather than the amount of aggressive behaviour. HR pigs, for instance, bullied (i.e. chased surrendering pigs) more often (P=0.009) and their fighting behaviour was less affected by their relative body weight than that of LR pigs. Post-weaning E pigs showed relatively higher levels of exploratory behaviour (P=0.02) and less oral manipulative behaviour (P=0.04) than post-weaning B pigs. In particular, switching from a good quality environment (E) to a worse quality one (B) at weaning decreased exploratory behaviour on the next day, especially for LR pigs, who also tended to fight with and orally manipulate their pen mates more in that condition, and seemed to be more affected by a deterioration of the environment. Overall, pre-weaning enrichment increased aggression after weaning whereas post-weaning enrichment reduced it, and personality type related to some aspects of fighting behaviour. (C) 2011 Elsevier B.V. All rights reserved.

Staphylococcus rostri sp. nov., a haemolytic bacterium isolated from the noses of healthy pigs

Twenty coagulase-negative Staphylococcus strains displaying alpha-haemolysis (delta-haemolysin) on sheep-blood agar were isolated from the noses of different pigs in Switzerland. The strains were Gram-stain-positive, non-motile cocci, catalase-positive and coagulase-negative. Sequence analysis of the 16S rRNA gene, sodA, rpoB, dnaJ and hsp60 and phylogenetic characteristics revealed that the strains showed the closest relatedness to Staphylococcus microti CCM 4903(T) and Staphylococcus muscae DSM 7068(T). The strains can be differentiated from S. microti by the absence of mannose fermentation and arginine arylamidase and from S. muscae by the absence of beta-glucuronidase activity and production of alkaline phosphatase. The chosen type strain ARI 262(T) shared 20.1 and 31.9 % DNA relatedness with S. microti DSM 22147(T) and S. muscae CCM 4903(T), respectively, by DNA-DNA hybridization. iso-C(15 : 0), anteiso-C(15 : 0) and iso-C(17 : 0) were the most common fatty acids. Cell-wall structure analysis revealed the peptidoglycan type A3alpha l-Lys-Gly(2)-l-Ser-Gly (type A11.3). The presence of teichoic acid was determined by sequencing the N-acetyl-beta-d-mannosaminyltransferase gene tarA, which is involved in biosynthesis of ribitol teichoic acid. Menaquinone 7 (MK-7) was the predominant respiratory quinone. The G+C content of ARI 262(T) was 38.8 mol%. The isolated strains represent a novel species of the genus Staphylococcus, for which we propose the name Staphylococcus rostri sp. nov. The type strain is ARI 262(T) (=DSM 21968(T) =CCUG 57266(T)) and strain ARI 602 (=DSM 21969 =CCUG 57267) is a reference strain.

Antibiotic resistance profile of Staphylococcus rostri, a new species isolated from healthy pigs

Staphylococcus rostri is a newly described Staphylococcus species that is present in the nasal cavity of healthy pigs. Out of the 225 pigs tested at slaughterhouse, 46.7% carried the new species alone and 22% in combination with Staphylococcus aureus. An antibiotic resistance profile was determined for S. rostri and compared to that of S. aureus isolated from the same pig. Resistance to tetracycline specified by tet(M), tet(K) and tet(L), streptomycin (str(pS194)), penicillin (blaZ), trimethoprim (dfr(G)), and erythromycin and clindamycin (erm genes), were found in both species; however, with the exception of streptomycin and trimethoprim, resistance was higher in S. aureus. S. rostri isolates display very low genetic diversity as demonstrated by pulsed-field gel electrophoresis, which generated two major clusters. Several clonal complexes (CC1, CC5, CC9, CC30 and CC398) were identified in S. aureus with CC 9 and CC 398 being the most frequent. Our study gives the first overview of the distribution, genetic relatedness, and resistance profile of one coagulase-negative Staphylococcus species that is commonly present in the nares of healthy pigs in Switzerland, and shows that S. rostri may harbor resistance genes associated with transferable elements like Tn916.