Gentamicin concentrations in synovial fluid obtained from the tarsocrural joints of horses after implantation of gentamicin-impregnated collagen sponges

In vitro Elution of Penicillin, Ampicillin, Tetracycline, Tulathromycin, and Florfenicol From Plaster of Paris Beads

The objectives of this study were to report a recipe for making antibiotic impregnated Plaster of Paris (AI-PoP) beads using penicillin, ampicillin, tetracycline, tulathromycin, and florfenicol and to determine the in vitro elution rates of those antibiotics in the beads. The AI-PoP beads were made using Plaster of Paris powder, antibiotic, and water, cured for 24 h, sterilized by ethylene oxide, and stored up to 5 months before testing. For each antibiotic, 20 beads were combined with bovine serum in sterile tubes and incubated at 37°C on a rocker. Serum was replaced at intervals over the 14 days study period, and antibiotic concentrations were determined by high pressure liquid chromatography with mass spectrometry. Separately, in a proof-of-concept study, the growth of E. coli and T. pyogenes in eluent from 10 beads for each antibiotic was quantified by flow cytometry. Antibiotic was detected in AI-PoP bead eluent for 14 days for all but the ampicillin beads, for which antibiotic was detected for 8 days. The concentration of antibiotic in eluent was greater than the minimum inhibitory concentration (MIC) of tested bacteria for the entire study period for penicillin, tetracycline, tulathromycin, and florfenicol. The concentration of ampicillin remained greater than the MIC of E. coli for 4 days and T. pyogenes for 6 days. The colony forming units (CFU)/ml of live E. coli and T. pyogenes was reduced over a 72-h period by 1-3 log10 CFU, with the exception of tetracycline, which reduced CFU/ml of T. pyogenes by Collapse

Key Words

• Plaster of Paris
• antibiotics
• cattle
• elution
• wound infection

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Affiliation(s)

Paul Merkatoris Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
Jennifer Schleining Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX, United States
Adam Krull Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
David Borts Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
Virginia Fajt Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX, United States

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Collagen-Based Tissue Engineering Strategies for Vascular Medicine

Cardiovascular diseases (CVDs) account for the 31% of total death per year, making them the first cause of death in the world. Atherosclerosis is at the root of the most life-threatening CVDs. Vascular bypass/replacement surgery is the primary therapy for patients with atherosclerosis. The use of polymeric grafts for this application is still burdened by high-rate failure, mostly caused by thrombosis and neointima hyperplasia at the implantation site. As a solution for these problems, the fast re-establishment of a functional endothelial cell (EC) layer has been proposed, representing a strategy of crucial importance to reduce these adverse outcomes. Implant modifications using molecules and growth factors with the aim of speeding up the re-endothelialization process has been proposed over the last years. Collagen, by virtue of several favorable properties, has been widely studied for its application in vascular graft enrichment, mainly as a coating for vascular graft luminal surface and as a drug delivery system for the release of pro-endothelialization factors. Collagen coatings provide receptor-ligand binding sites for ECs on the graft surface and, at the same time, act as biological sealants, effectively reducing graft porosity. The development of collagen-based drug delivery systems, in which small-molecule and protein-based drugs are immobilized within a collagen scaffold in order to control their release for biomedical applications, has been widely explored. These systems help in protecting the biological activity of the loaded molecules while slowing their diffusion from collagen scaffolds, providing optimal effects on the targeted vascular cells. Moreover, collagen-based vascular tissue engineering substitutes, despite not showing yet optimal mechanical properties for their use in the therapy, have shown a high potential as physiologically relevant models for the study of cardiovascular therapeutic drugs and diseases. In this review, the current state of the art about the use of collagen-based strategies, mainly as a coating material for the functionalization of vascular graft luminal surface, as a drug delivery system for the release of pro-endothelialization factors, and as physiologically relevant in vitro vascular models, and the future trend in this field of research will be presented and discussed.

A review of local antibiotic implants and applications to veterinary orthopaedic surgery

In the face of increasing incidence of multidrug resistant implant infections, local antibiotic modalities are receiving increased attention for both infection prophylaxis and treatment. Local antibiotic therapy that achieves very high antibiotic drug concentrations at the site of the implant may represent an avenue for treatment of biofilmforming bacterial pathogens. Randomized controlled trials in human patients have demonstrated an infection risk reduction when antibiotic-impregnated cement is used for infection prophylaxis in implanted joint prostheses, and when a gentamicin-impregnated collagen sponge is used for infection prophylaxis in midline sternotomy. The other modalities discussed have for the most part yet to be evaluated in randomized controlled trials in veterinary or human patients. In general, the in vivo pharmacokinetics and appropriate dosing profiles for local antibiotic modalities have yet to be elucidated. Toxicity is possible, and attention to the dose applied is warranted.

Septic Arthritis, Physitis, and Osteomyelitis in Foals

Despite differences in etiology and diagnostics, the mainstay of therapy in the foal is similar to the adult: local lavage and/or debridement and local antimicrobial therapy. When musculoskeletal infection is concurrent with neonatal sepsis, the prognosis for survival is fair. When musculoskeletal infection is the primary problem, the prognosis is fair to good for survival of synovial, bony, and physeal infections with appropriate and aggressive local therapy. Recent literature may indicate that prognosis for survival and potential athleticism in foals that are treated expediently with local therapies and are without comorbidities may be more favorable than has been previously indicated.

Pharmacokinetics and local tolerance of cefovecin sodium after intra-articular administration in horses

Searching for new therapeutic options against septic arthritis in horses, this research was focused on the study of the kinetics and local side effects after the intra-articular treatment of horses with cefovecin sodium. A single dose (240 mg) of the drug (Convenia^® ) was administered into the radiocarpal joint of adult healthy horses (n = 6), and drug concentrations in plasma and synovial fluid were determined by high-performance liquid chromatography (HPLC). Local tolerance was also studied based on the modification of different joint physiopathological parameters (pH, cellular, and protein concentration in synovial fluid). Although no clinically relevant joint damage was noticed, significant increases in the protein concentrations at 5 min and in the cellular concentration at 30 min after cefovecin administration were observed in the treated radiocarpal joints. The duration of the cefovecin above the minimal inhibitory concentration (MIC) ≤1 μg/mL was 28.80 ± 2.58 h in the radiocarpal joint and 16.00 ± 2.86 h in plasma. The results of this study showed that intra-articular administration of cefovecin sodium in horses could be considered in the future to manage septic arthritis in horses, as it offers a good pharmacokinetic behavior and good local tolerance.

Intra-articular pharmacokinetics of a gentamicin impregnated collagen sponge in the canine stifle: an experimental study

OBJECTIVE

To investigate local and systemic pharmacokinetics of gentamicin after intra-articular implantation of a gentamicin impregnated collagen sponge (GICS) in the inflamed canine joint.

STUDY DESIGN

Descriptive repeated measures experimental study.

ANIMALS

Dogs (n = 9).

METHODS

Stifle joint inflammation was caused by urate injection. Twenty-four hours later a GICS (gentamicin dose, 6 mg/kg) was arthroscopically implanted. Synovial fluid and plasma gentamicin concentrations were measured for 14 days after implantation, and pharmacokinetic parameters modeled using statistical moment analyses.

RESULTS

Intra-articular gentamicin concentrations fell to sub-MIC for Staphylococcus sp. (4 µg/mL) by 22.4 hours (95% CI: 18.6-26.2) after sponge implantation. Cmax synovial was 2397 µg/mL (95%CI: 1161-3634 µg/mL) at 1.2 hours (95%CI: 0.5-1.8 hours). Plasma gentamicin concentrations achieved levels of Cmax plasma  = 8.0 µg/mL (95%CI: 6.1-10.0 µg/mL) at 1.5 hours (95%CI: 0.8-2.1) after GICS placement and fell below target trough of 2.0 µg/mL by 5.6 hours (95%CI: 4.7-6.5 hours) after GICS placement.

CONCLUSIONS

Intra-articular gentamicin concentration after GICS placement at an IV-equivalent dose reached high levels and declined rapidly. The maximum plasma levels attained were ∼1/3 of the recommended sub-toxic target for people after parenteral gentamicin administration.

In vitro elution of amikacin and ticarcillin from a resorbable, self-setting, fiber reinforced calcium phosphate cement

OBJECTIVE

To determine in vitro elution characteristics of amikacin and ticarcillin from fiber reinforced calcium phosphate beads (FRCP).

SAMPLE POPULATION

Experimental.

METHODS

FRCP beads with water (A), amikacin (B), ticarcillin/clavulanate (C), or both amikacin and ticarcillin/clavulanate (D) were bathed in mL phosphate-buffered saline (PBS) at 37°C, 5% CO(2) and 95% room air. PBS was sampled (eluent) and beads were placed in fresh PBS at time points 1 and 8 hours and 1, 2, 3, 4, 5, 6, 7, 10, 12, 14, 18, 21, 25, 28, 35, 42, 49, and 56 days. Antibiotic concentration and antimicrobial activity of eluent against Escherichia coli, Staphylococcus aureus, and Klebsiella pneumoniae were determined.

RESULTS

Both antibiotics eluted in a bimodal pattern. Beads with a single antibiotic eluted 20.8 ± 2.5% of amikacin and 29.5 ± 0.8% of ticarcillin over 56 days. Coelution of the antibiotics resulted in a lower proportion (AUC(0-∞) ) of antibiotics eluted for both amikacin (9.5 ± 0.2%) and ticarcillin (21.7 ± 0.09%). Bioassay of antimicrobial activity of the eluent (t = 1, 8, and 24 hours) established reduced antimicrobial activity of amikacin from combination beads (D).

CONCLUSIONS

FRCP beads with amikacin or ticarcillin/clavulanate, but not the combination, are suitable carriers for wound implantation.

CLINICAL RELEVANCE

Duration before complete resorption of FRCP beads in vivo should be determined before clinical use as a resorbable depot. The results of this study underscore the importance of testing drug combinations, despite success of the combination systemically, before their use in local applications.

Antimicrobial delivery by intrasynovial catheterisation with systemic administration for equine synovial trauma and sepsis

OBJECTIVE

To present the technique for intra-articular catheter placement and report the clinical outcomes of 38 cases of equine synovial trauma and/or infection treated with broad-spectrum antimicrobials administered via an intrasynovial catheter (ISC).

DESIGN

Retrospective study.

PROCEDURE

Medical records of 38 horses treated for synovial trauma and sepsis with frequent antimicrobial administration through an ISC from 1995 to 2008 were reviewed. Follow-up information was obtained via clinical re-evaluation or telephone contact with the owners.

RESULTS

The majority of horses (84%) received amikacin and Timentin(R) four times daily. In addition, synovial lavage through the ISC was carried out in 27 horses (71%). Only radiological evidence of osteolysis had a significant negative impact on both lameness at the time of hospital discharge and the long-term outcome. In total, 92% of horses treated with frequent antimicrobial administration through an ISC had clinical resolution of infection. Catheter obstruction occurred in three cases, necessitating replacement or removal, and two synovial fistulae developed at sites of open drainage. The majority of horses treated had a favourable outcome, with 86% being at least pasture sound and 43% returned to riding.

CONCLUSION

Septic synovial structures treated with frequent antimicrobial administration through an ISC had a good prognosis for survival and 43% returned to riding, which is consistent with the results of other studies. The use of a simple ISC should be considered when broad-spectrum intrasynovial antimicrobial administration and lavage of a septic synovial structure are indicated.