Distribution of RTX toxin genes in strains of [Actinobacillus] rossii and [Pasteurella] mairii

Strains of [Actinobacillus] rossii, [Pasteurella] mairii and [Pasteurella] aerogenes can be isolated from abortion in swine. The RTX toxin Pax has previously been found only in those [P.] aerogenes strains isolated from abortion. Nothing is known about RTX toxins in field isolates of the other two species. To gain insight into the distribution of selected RTX toxin genes and their association with abortion, PCR screening for the pax, apxII and apxIII operons on 21 [A.] rossii and seven [P.] mairii isolates was done. Since species can be phenotypically misidentified, the study was backed up by a phylogenetic analysis of all strains based on 16S rRNA, rpoB and infB genes. The pax gene was detected in all [P.] mairii but not in [A.] rossii strains. No apx genes were found in [P.] mairii but different gene combinations for apx were detected in [A.] rossii strains. Most of these strains were positive for apxIII, either alone or in combination with apxII. Whereas pax was found to be associated to strains from abortion no such indication could be found with apx in [A.] rossii strains. Phylogenetically [A.] rossii strains formed a heterogeneous cluster separated from Actinobacillus sensu stricto. [P.] mairii strains clustered with [P.] aerogenes but forming a separate branch. The fact that [P.] aerogenes, [P.] mairii and [A.] rossii can phylogenetically clearly be identified and might contain distinct RTX toxin genes allows their proper diagnosis and will further help to investigate their role as pathogens.     

SSR marker analysis of Monilinia fructicola from Swiss apricots suggests introduction of the pathogen from neighbouring countries and the United States

Monilinia fructicola is a quarantine fungal pathogen in Europe, but many major stone fruit growing countries in Europe have reported its presence recently. In Switzerland, the fungus was first found in a single apricot orchard in 2008. This study confirms the presence of M. fructicola in nine out of 22 commercial orchards in Canton Valais, Switzerland. Five simple sequence repeat markers (SSRs) were developed for M. fructicola and samples from Switzerland, Spain, Italy, France and the United States were analysed and compared in order to assess the genetic diversity of the pathogen, identify the origin of the disease, and verify if the fungus reproduces sexually in Europe. In the 119 European samples analysed, 12 different haplotypes were found, indicating a relatively high genetic diversity of the pathogen considering that the first report in Europe was 10 years ago. Three haplotypes found in Europe were identical to those found in the American samples (two from the east coast and one from the west coast). Population structure analysis suggests that the European population is derived from at least two ‘invasion’ events probably originating from the US (one from the east coast, the other from the west coast). Preliminary evidence of sexual reproduction of M. fructicola in Europe is reported.     

Comparing silvopastoral systems and prospects in eight regions of the world

Silvopasture systems combine trees, forage, and livestock in a variety of different species and management regimes, depending on the biophysical, economic, cultural, and market factors in a region. We describe and compare actual farm practices and current research trials of silvopastoral systems in eight regions within seven countries of the world: Misiones and Corrientes provinces, Argentina; La Pampa province, Argentina; northwestern Minas Gerais, Brazil; the Aysén region of Patagonia, Chile; the North Island of New Zealand; the Southeast United States; Paraguay; and Uruguay. Some countries use native trees and existing forests; some use plantations, particularly of exotic species. Natural forest silvopasture systems generally add livestock in extensive systems, to capture the benefits of shade, forage, and income diversification without much added inputs. Plantation forest systems are more purposive and intensive, with more focus on joint production and profits, for small owners, large ranches, and timber companies. Trends suggest that more active management of both natural and planted silvopastoral systems will be required to enhance joint production of timber and livestock, achieve income diversification and reduce financial risk, make more profit, improve environmental benefits, and realize more resilience to adapt to climate change.     

Coprological analyses on apparently healthy Alpine ibex (Capra ibex ibex) from two Swiss colonies

To provide baseline parasitological data for health surveillance in free-ranging Alpine ibex (Capra ibex ibex), we assessed the endoparasite population and level of parasitism in apparently healthy ibex. Faecal samples from 148 ibex were collected between 2006 and 2008 in two different Swiss ibex colonies. They were analysed by coprology, including combined sedimentation/flotation method, sedimentation method, Baermann funnel technique and Ziehl-Neelsen staining. Gastrointestinal parasites and lungworms were identified in 100% and 81.8% of the examined animals, respectively. Highest prevalences were recorded for gastrointestinal strongylids other than Nematodirus/Marshallagia spp. (100%), Eimeria spp. (100%), Muellerius spp. (79.8%) and Nematodirus/Marshallagia spp. (79.0%). We report for the first time Cryptosporidium sp. in free-ranging Alpine ibex and Cystocaulus spp. in free-ranging ibex from Switzerland. On average, ibex were infected with 3.9 different parasites taxa (range: 1-8). Parasite prevalence and diversity varied significantly between sexes, study sites and seasons. Parasite egg output was low in 95.7% and moderate in 5.3% of the samples. Overall, the results indicate that Alpine ibex are widely infected with endoparasites and suggest that multiple infections are very common in apparently healthy populations. Furthermore, our data underline the potential influence of factors such as sex, study site and season on parasitological findings.     

Molecular epidemiology and genetic linkage of macrolide and aminoglycoside resistance in Staphylococcus intermedius of canine origin

A collection of 77 Staphylococcus intermedius isolates from dogs and cats in Switzerland was examined for resistance to erythromycin. Resistance profiles for 14 additional antibiotics were compared between erythromycin-resistant and susceptible isolates. A resistance prevalence of 27% for erythromycin was observed in the population under study. Complete correlation between resistance to erythromycin, and to spiramycin, streptomycin, and neomycin was observed. The erythromycin-resistant isolates all had a reduced susceptibility to clindamycin when compared to the erythromycin-susceptible isolates. Both constitutive and inducible resistance phenotypes were observed for clindamycin. Ribotyping showed that macrolide-aminoglycoside resistance was randomly distributed among unrelated strains. This suggests that this particular resistance profile is not related to a single bacterial clone but to the horizontal transfer of resistance gene clusters in S. intermedius populations. The erythromycin-resistant isolates were all carrying erm(B), but not erm(A), erm(C), or msr(A). The erm(B) gene was physically linked to Tn5405-like elements known as resistance determinants for streptomycin, streptothricin, neomycin and kanamycin. Analysis of the region flanking erm(B) showed the presence of two different groups of erm(B)-Tn5405-like elements in the S. intermedius population examined and of elements found in Gram-positive species other than staphylococci. This strongly suggests that erm(B) or the whole erm(B)-Tn5405-like elements in S. intermedius originate from other bacterial species, possibly from enterococci.     

The efficacy of a standardised product from dried leaves of Solanum glaucophyllum as source of 1,25-dihydroxycholecalciferol for poultry

1. Chemical characterisation of an extract of Solanum glaucophyllum (SG) leaves affirmed the predominant presence of 1,25-dihydroxycholecalciferol (1,25(OH)₂D₃) glycosides. The compound 1-(ß-D-glucopyranosyl)-1α,25-dihydroxycholecalciferol was isolated for the first time from a natural source.

2. Vitamin D activity of the extract was confirmed by the calcaemic properties shown in a quail eggshell bioassay. The results suggested a 1,25(OH)₂D₃ bioavailability of approximately 15%.

3. A broiler feeding experiment replicated in time was carried out with 6 treatments. A basic control diet containing 25 μg cholecalciferol/kg was supplemented with 2.5 and 5 μg free 1,25(OH)₂D₃/kg, with a product based on dried SG leaves (Panbonis) providing 10 μg of 1,25(OH)₂D₃-glycosides/kg, with two concentrations of an SG extract providing 8.8 and 37.8 μg of 1,25(OH)₂D₃-glycosides/kg.

4. Tibia breaking strength and stiffness were numerically greater in all treatment groups with free 1,25(OH)₂D₃ and with SG products compared to controls, though the overall treatment effects only had probabilities in the range of P = 0.07 to P = 0.1. Values for both characteristics increased progressively, with additions of synthetic 1,25(OH)₂D₃; values with the dried SG product were similar to those with 5 μg synthetic 1,25(OH)₂D₃/kg.

5. Plasma calcium was mildly elevated (P < 0.05) in treatment groups. The SG extract treatment containing 37.8 μg 1,25(OH)₂D₃/kg gave the highest plasma calcium concentration and lowest bodyweight, signs of marginal hypervitaminosis D. Plasma 1,25(OH)₂D₃ concentrations were in the normal range for all treatments.

6. Tibial dyschondroplasia occurred in only one replicate. The incidences were 31% in controls but considerably lower or zero with all other treatments.

7. Bioavailability of 1,25(OH)₂D₃ in the SG product seemed to be higher in broiler chickens than in Japanese quails.

8. It is concluded that the inclusion of the dried SG product as a source of vitamin D₃ in broiler diets at a dietary concentration of 1 g/kg, providing 10 μg 1,25(OH)₂D₃/kg, is safe and efficacious.     

Camel Streptococcus agalactiae populations are associated with specific disease complexes and acquired the tetracycline resistance gene tetM via a Tn916-like element

Camels are the most valuable livestock species in the Horn of Africa and play a pivotal role in the nutritional sustainability for millions of people. Their health status is therefore of utmost importance for the people living in this region. Streptococcus agalactiae, a Group B Streptococcus (GBS), is an important camel pathogen. Here we present the first epidemiological study based on genetic and phenotypic data from African camel derived GBS. Ninety-two GBS were characterized using multilocus sequence typing (MLST), capsular polysaccharide typing and in vitro antimicrobial susceptibility testing. We analysed the GBS using Bayesian linkage, phylogenetic and minimum spanning tree analyses and compared them with human GBS from East Africa in order to investigate the level of genetic exchange between GBS populations in the region. Camel GBS sequence types (STs) were distinct from other STs reported so far. We mapped specific STs and capsular types to major disease complexes caused by GBS. Widespread resistance (34%) to tetracycline was associated with acquisition of the tetM gene that is carried on a Tn916-like element, and observed primarily among GBS isolated from mastitis. The presence of tetM within different MLST clades suggests acquisition on multiple occasions. Wound infections and mastitis in camels associated with GBS are widespread and should ideally be treated with antimicrobials other than tetracycline in East Africa.     

Optimization of an oxygen-based approach for community-level physiological profiling of soils

Current approaches for rapid assessment of carbon source utilization by whole soil communities (i.e., community-level physiological profiling or CLPP) provide a limited, biased view of microbial communities with little connection to in situ activities. We developed an alternative CLPP approach based upon fluorometric detection of dissolved oxygen consumption in a microtiter platform which offers flexible manipulation of experimental factors. In the attempt to reduce oxygen re-dissolution, the wells were filled with liquid to very near the top and sealed. We found that filling the wells with 240 vs. 150 μl of sample improved the sensitivity of the system to discern both the response to a substrate amendment as low as 10 mg l⁻¹ and un-amended, endogenous respiration. The preparation of a soil slurry facilitates inoculation into the microplate. Disruption of soil samples had a limited effect on the endogenous respiration in comparison to intact soil microbags in a 24-well microplate. Storage time (up to 33 days) reduced the level of activity in intact soil microbags but not in disrupted samples. A microcosm fertilization experiment was set to study the effects of N availability on the respiratory response in the plates. The use of soil organic carbon (SOC) and amended C-substrates (50 mg l⁻¹) was increased by the addition of nitrogen (N) in the plate, and appeared N-limited shortly after microcosm fertilization. The addition of the eukaryotic inhibitor cycloheximide delayed the initial increase in fluorescence (time to minimum response) of several C sources (casein, acetate, asparagine, coumaric acid), varying among soils, which could be explained by the fungal use of these compounds. However, the extent of the inhibition caused by cycloheximide did not increase at higher fungal to bacteria ratios as estimated by PLFA analysis, indicating that the direct estimation of the fungal biomass from cycloheximide addition is not feasible. This paper provides an optimized, standardized protocol for soil analysis, and sets the basis for further validation studies that will continue to define the underlying capabilities/biases of this approach.     

Comparative analysis of the lppA locus in Mycoplasma capricolum subsp. capricolum and Mycoplasma capricolum subsp. capripneumoniae.

The lppA gene, encoding the lipoprotein named LppA[Mcaca] was characterised in Mycoplasma capricolum subsp. capricolum. It encodes a lipoprotein with an apparent molecular mass of 57 kDa as determined by SDS-PAGE. Using antibodies directed against recombinant LppA[Mcaca], we showed the expression of this lipoprotein in all M. capricolum subsp. capricolum by immunoblot analysis. The serum did not cross-react with other members of the Mycoplasma mycoides cluster, hence showing that LppA[Mcaca] was antigenically specific to M. capricolum subsp. capricolum. The lppA gene was conserved within the subspecies and was used for the development of a specific PCR assay for the identification of M. capricolum subsp. capricolum. The taxonomically related Mycoplasma capricolum subsp. capripneumoniae (F38) was found to contain an lppA-pseudo-gene. It showed high similarity to functional lppA genes of other mycoplasmas in the M. mycoides cluster. However, it contained interrupted open reading frames. Moreover, the nucleotide sequence of the lppA pseudo-genes in different strains of M. capricolum subsp. capripneumoniae were quite variable. Interestingly, the lppA pseudo-gene had a size similar to that of the functional lppA genes of other mycoplasmas of the M. mycoides cluster and occupied the same genomic location as the latter ones in the vicinity of the mtlD genes. This study showed that all members of the M. mycoides cluster contain each a species-, subspecies- respectively type- specific lppA gene analogue which encodes a lipoprotein that has structural and functional relationship to the surface lipoprotein LppA [MmymySC], previously named P72, of M. mycoides subsp mycoides SC, with the exception of M. capricolum subsp. capripneumoniae which seems not to express an LppA analogue.     

Report of the 3rd Havemeyer workshop on allergic diseases of the Horse, Hólar, Iceland, June 2007

Allergic diseases occur in most mammals, although some species such as humans, dogs and horses seem to be more prone to develop allergies than others. In horses, insect bite hypersensitivity (IBH), an allergic dermatitis caused by bites of midges, and recurrent airway obstruction (RAO), a hyperreactivity to stable born dust and allergens, are the two most prevalent allergic diseases. Allergic diseases involve the interaction of three major factors: (i) genetic constitution, (ii) exposure to allergens, and (iii) a dysregulation of the immune response determined by (i) and (ii). However, other environmental factors such as infectious diseases, contact with endotoxin and degree of infestation with endoparasites have been shown to influence the prevalence of allergic diseases in humans. How these factors may impact upon allergic disease in the horse is unknown at this time. The 3rd workshop on Allergic Diseases of the Horse, with major sponsorship from the Havemeyer Foundation, was held in Hólar, Iceland, in June 2007 and focussed on immunological and genetic aspects of IBH and RAO. This particular venue was chosen because of the prevalence of IBH in exported Icelandic horses. The incidence of IBH is significantly different between Icelandic horses born in Europe or North America and those born in Iceland and exported as adults. Although the genetic factors and allergens are the same, exported adult horses show a greater incidence of IBH. This suggests that environmental or epigenetic factors may contribute to this response. This report summarizes the present state of knowledge and summarizes important issues discussed at the workshop.