Multi-drug-resistant Enterococcus spp. as a cause of non-responsive septic synovitis in three horses

Abstract

CASE HISTORY: Three Thoroughbred horses, a 6-week-old filly (Case 1), a 15-year-old broodmare (Case 2) and a yearling filly (Case 3), sustained synovial sepsis secondary to trauma.

CLINICAL FINDINGS: Case 1 presented with a heel bulb laceration communicating with the distal interphalangeal joint. Arthroscopic lavage was performed and treatment commenced using systemic and local broad spectrum antimicrobial drugs. A pure growth of multi-drug-resistant (MDR) Enterococcus gallinarum was cultured from samples of synovium and joint fluid. Antimicrobial treatment was changed according to the susceptibility results. Response to treatment was poor and despite repeat arthroscopic lavage and intra-osseous regional perfusion of antimicrobials the filly was subject to euthanasia 24 days after the initial injury. Post-mortem examination confirmed septic synovitis, cartilage degeneration and osteomyelitis.

Case 2 sustained a full thickness wound to the carpus which was sharply debrided and closed. The wound dehisced with effusion within the tendon sheath. Drainage was established and treatment included systemic broad spectrum antimicrobials, topical lavage with povodine-iodine and manuka honey infusion. A mixed infection including MDR Enterococcus faecalis was cultured from the synovial fluid. Antebrachiocarpal joint effusion developed 21 days after initial injury and joint sepsis was confirmed. Arthroscopic lavage and tendon sheath debridement were performed, followed by treatment with systemic and local antimicrobials. The mare improved and was discharged. Three months later lameness recurred and corticosteroids were administered intra-articularly. The mare became non-weight bearing lame and was subject to euthanasia. Post-mortem examination confirmed joint sepsis of the antebrachiocarpal and intercarpal joint.

Case 3 presented with a complete articular open fracture of the tibial crest. Under general anaesthesia the fracture was stabilised and the wounds debrided and closed. Systemic broad-spectrum antimicrobials were administered. Six days later the wound dehisced and a bone fragment was removed. Three weeks post-surgery the wound deteriorated with a purulent discharge. Culture of the discharge revealed a mixed bacterial infection, including a MDR Enterococcus faecalis. Femoropatellar joint involvement was confirmed, and treatment included joint lavage, local and systemic antibiosis, and manuka honey instilled into the wound. The filly initially improved, and then deteriorated such that euthanasia was performed.

DIAGNOSIS: All three cases had synovial sepsis with MDR Enterococcus spp.

CLINICAL RELEVANCE: Increased awareness of MDR pathogens in equine wound infections is essential. Prompt diagnostic testing, appropriate therapy, infection control strategies and on-going monitoring and management are vital to limit the clinical impact of these organisms.     

Seedling Growth of Agronomic Crops in Crude Oil Contaminated Soil

Phytoremediation of hydrocarbon‐contaminated soil shows promise as a low‐cost alternative to most remediation methods. This study evaluated seedling growth of six crop species in crude oil contaminated soils. The experiments were conducted in a greenhouse. Weathered crude oil was added to an Ipava silt loam soil at the rate of 0 (control), 10, 50 and 100 g of crude oil kg^?1 of soil, which was then placed into pots. Irrigation was used to maintain soil moisture at approximately field capacity. Five seeds of Zea mays, Meticago sativa, Lolium perenne, Triticum aestivum, Glycine max or Vicia villosa were sown per pot. The experimental design was completely randomized with five replications per treatment. Germination and seedling height data were recorded on day 7, 14, 21 and 28. Plants were harvested on day 28, separated into shoots and roots and dried to measure biomass. Analysis of variance was used to determine treatment significance. Significant treatment mean values were separated using Tukey's Honestly Significant Difference Test. Based upon percent emergence and plant biomass production in contaminated soil, Z. mays and G. max seedlings show the greatest potential to enhance remediation.     

Antigenic stability of fimbriae of Bacteroides nodosus

Successful vaccination of sheep against footrot and attempts to eradicate the disease depend on there being a limit to the antigenic diversity of the causative bacterium, Bacteroides nodosus. Fimbrial antigenic variation was therefore investigated in vivo, both under conditions of chronic infection and under the pressure of a vaccine-induced immune response, to ascertain whether this represented an obstacle to such goals. Material was available from 5 experiments and although B. nodosus appeared to have undergone changes in its fimbrial antigens in one of these, the possibility that superinfection was responsible for the variation detected could not be ruled out because all sheep in this case were maintained at pasture. Overall, the results provided no evidence of fimbrial antigenic shift in B. nodosus in vivo and in conclusion, the survival of the organism in the sheep's foot, both in long-term natural infection and following vaccination, must therefore be related to factors other than the ability to undergo antigenic variation in order to evade the host's immune response.     

Phytoremediation and Modeling of Contaminated Soil using Eastern Gamagrass and Annual Ryegrass

The effectiveness of a warm season grass (eastern gamagrass), a cool season grass (annual ryegrass) and a rotation of warm and cool season grasses in the remediation of soil freshly contaminated with trinitrotoluene (TNT) and polybrominated biphenyls (PBBs) was evaluated. A total of 96 columns were filled with a Weswood silt loam soil that was mixed with TNT and PBB compounds to a target concentration of 10 mg of each contaminant. Chemical losses during this two-year field lysimeter experiment were similar for all experimental treatments and at all depths. Although higher microbial biomass was found in the rhizosphere soil, enumeration of soil microorganisms revealed a robust population in both the bulk and rhizosphere soils and the microbial growth was not dependent on root exudates only. Microbial degradation rates in the freshly contaminated soil were more affected by soil properties and the chemical characteristics of the contaminant than the presence of roots. The field data collected from the lysimeter experiment was used to calibrate a recently developed phytoremediation model. The phytoremediation computer model successfully simulated TNT soil concentrations in the column lysimeters. The model may be a valuable tool for the selection and optimization of phytoremediation methods at contaminated field sites.     

SELENIUM FERTILIZATION INFLUENCES BIOMASS,ELEMENTAL ACCUMULATIONS,AND PHYTOCHEMICAL CONCENTRATIONS IN WATERCRESS

Watercress (Nasturtium officinale R. Br.) produces carotenoids and sulfur-containing glucosinolates (GSs) beneficial to human health. Selenium (Se) imparts dietary health properties and substitutes for S in plant biochemical pathways. Experimental objectives were to determine the influence of Se fertilization on 1) biomass, 2) elemental accumulations, 3) carotenoids, and 4) glucosinolates in watercress leaf and shoot tissues. Watercress was greenhouse grown in solution culture with Se treatments of 0, 0.125, 0.25, 0.50, 1.0, 2.0, and 4.0 mg Se L^?1, delivered as sodium selenate (Na₂SeO₄). Fresh and dry biomass were unaffected while shoot tissue Se (P = 0.057) and S (P = 0.003) increased linearly in response to increasing Se treatments. Linear decreases were measured for β-carotene (P = 0.017) and lutein (P = 0.018) in response to increasing Se. Total levels of GS increased, then decreased quadratically (P = 0.003). Results indicate that Se supplementation can increase Se tissue concentrations and GS in watercress; however, carotenoids were negatively affected.