Evaluation of the hoof centre-of-pressure path in horses affected by chronic osteoarthritic pain.

INTRODUCTION: The Centre of Pressure (COP) is the single point summarising all forces transferred to the hoof during the stance phase of a stride. COP path (COPp) is the trajectory that COP follows from footstrike to lift-off. Aim of the present study was to characterize the COP and COPp in horses affected by osteoarthritis and chronic lameness. MATERIALS AND METHODS: Seventeen adult horses with a diagnosis of osteoarthritis and single limb chronic lameness were recruited. The COP was recorded using a wireless pressure measuring system (TekScan®) with sensors taped to the hooves (either fore- or hind limb, depending on lameness location). The COPp coordinates were further processed. Procrustes analysis was performed to assess the variability of single strides COPp and average COPp among strides, gaits, and limbs by calculating Procrustes distances (D-values). A linear mixed-effects model was run to analyse D-values differences for lame and sound limbs. Additionally, average COPp D-values and COPp hoofprint shape indices were compared for lame and sound limbs with the Signed Rank Test. RESULTS: At walk and trot the single-stride COPp D-values were significantly lower in lame than in sound limbs (marginal effects p<0.001). Analysis of the average COPp D-values confirmed that each hoof COPp is highly consistent with itself over subsequent trials but is different from the contralateral. COPp and hoofprint shape indices did not differ between sound and lame limbs. Footstrike and lift-off within the hoofprint showed that most horses had lateral footstrike and lift-off, independently of the lameness location. CONCLUSION: Our findings are in line with previous observations that COPp are highly repetitive and characteristic for each horse and limb. There seems to be a further decrease in COPp variability in the presence of a painful limb pathology.

Novel ß-Lactamase blaARL in Staphylococcus arlettae.

Whole-genome sequencing of penicillin-resistant Staphylococcus arlettae strain SAN1670 from bovine mastitis milk revealed a novel ß-lactamase operon consisting of the ß-lactamase-encoding gene blaARL, the antirepressor-encoding gene blaR1ARL, and the repressor-encoding gene blaIARL. The functionality of blaARL was demonstrated by gene expression in Staphylococcus aureus. The blaARL operon was chromosomally located in SAN1670 and present in 10 additional unrelated strains, suggesting intrinsic penicillin resistance in S. arlettae. Furthermore, a GenBank search revealed more unique potential ß-lactamases in Staphylococcus species. IMPORTANCE Penicillins are an important group of antibiotics used to treat various types of infections caused by Gram-positive bacteria. So far, the blaZ gene was the only known ß-lactamase gene in staphylococci. However, other putative ß-lactamases were identified, and one of them was shown to be a novel functional ß-lactamase encoded by blaARL in Staphylococcus arlettae, further limiting treatment options.

New Macrolide-Lincosamide-Streptogramin B Resistance Gene erm(48) on the Novel Plasmid pJW2311 in Staphylococcus xylosus.

Whole-genome sequencing of Staphylococcus xylosus strain JW2311 from bovine mastitis milk identified the novel 49.3-kb macrolide-lincosamide-streptogramin B (MLSB) resistance plasmid pJW2311. It contained the macrolide resistance gene mph(C), the macrolide-streptogramin B resistance gene msr(A), and the new MLSB resistance gene erm(48) and could be transformed into Staphylococcus aureus by electroporation. Functionality of erm(48) was demonstrated by cloning and expression in S. aureus.