Trainee: Alanna Zantingh, Resident in Large Animal Medicine
Contact Information: Email: firstname.lastname@example.org; Phone: 607-253-3110
Sponsor: Clinical Research Grants Program
Grant Number: N/A
Title: Regional Limb Perfusion of Amikacin Alone and in Combination with Ticarcillin
Annual Direct Cost: $3,550
Project Period: 02/01/11-01/31/12
DESCRIPTION (provided by applicant): Aminoglycoside and beta-lactam antimicrobials are commonly utilized, both alone and in combination, as systemic and local medications in human and veterinary medicine. The efficacy of this combination of drug classes administered systemically is well known and the combination is widely used in local applications in equine veterinary medicine (Stewart et al 2010, Kettner et al 2003, Palmer and Hogan 1999). However, there are no reports of the effect of their combination when used in local applications. This may be a major clinical oversight as beta-lactam and aminoglycoside antibiotics undergo a chemical interaction when confined to the same solution, leading to their inactivation. We want to test for an interaction when the combination is used in equine regional limb perfusion.
Our specific aims are 1) To determine the effect of regional limb perfusion with amikacin sulfate alone and in combination with ticarcillin on synovial concentration of amikacin and 2) To determine the effect of regional limb perfusion with amikacin sulfate alone and in combination with ticarcillin on synovial antimicrobial acitivity against amikacin and ticarcillin susceptible microorganisms, Klebsiella pneumonia, Escherichia coli and Staphylococcus aureus.
Regional limb perfusion will be performed on ponies that are anesthetized for a student surgical laboratory. Five hundred mg of amikacin in 30ml of lactated ringers solution (LRS) will be injected followed by 30ml of either LRS alone (group A) or 30ml LRS with 0.75g ticarcillin/clavulanate (group B). At 0, 15 and 30 minutes after injection, 1 ml of perfusate blood will be collected via the catheter. The tourniquet will be released after the 30 minute perfusate sample is collected. Following tourniquet release, 1 ml of synovial fluid will be collected from the middle carpal joint at 0, 30 and 60 minutes. The experiment will be repeated during the second student lab general anesthetic on the opposite forelimb: ponies that underwent group A treatment during the first general anesthetic, will undergo group B treatment, and vice versa. Amikacin concentration in serum and synovial samples will be determined by automated fluorescence polarization immunoassay in Dr. Schwark’s laboratory and bioactivity of serum and synovial samples will be determined against standard cultures of Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC51503 and Staphylococcus aureus ATCC25923 by agar diffusion method in Dr Schwark’s laboratory.
The work will be done entirely by Dr. Zantingh, a large animal surgery resident with oversight, assistance and instruction by Dr. Fubini during the in vivo sample collection, Dr. Schwark for the amikacin concentration assays and Dr. Watts during the antimicrobial activity assays. Dr. Zantingh will be off-clinics during these weeks and able to perform all aspects of the in vivo portion of the study. After completion of the in vivo sample collection, the samples will be stored at -80°C. At this temperature, there will be negligible antimicrobial degradation or interaction, allowing the in vitro assays (concentration and bioactivity) to be performed during Dr. Zantingh’s scheduled off-clinics weeks.