Influence of intravenous regional limb perfusion with amikacin sulfate on Staphylococcus aureus bioburden in distal limb wounds in horses.
Authors: Freeland Russell B, Morello Samantha L, DeLombaert Melissa, Rajamanickam Victora
Journal: Veterinary surgery : VS
Summary
# Editorial Summary Intravenous regional limb perfusion (IVRLP) is commonly used in equine practice to deliver high antibiotic concentrations to distal limb wounds, yet this 2017 experimental study questions its efficacy against established *Staphylococcus aureus* bioburden. Russell and colleagues created full-thickness wounds on the dorsal metacarpi of four horses, deliberately inoculated them with *S. aureus*, then treated one randomly assigned forelimb with amikacin sulphate via cephalic vein IVRLP on days 2–4 post-wounding, whilst the contralateral limb served as untreated control; the study was repeated in crossover design in two horses (six experiments total). Bacterial bioburden quantified from tissue biopsies revealed no significant difference between treated and control limbs at any timepoint (days 2, 5, or 8), with comparable frequencies of positive cultures in both groups, suggesting IVRLP failed to concentrate sufficient antibiotic within the wound bed itself. Tracer dye studies using methylene blue demonstrated that perfusion via the cephalic vein did not reliably deliver fluid to distal tissues, whereas palmar digital vein administration produced visible dye distribution in all tissues. These findings suggest that current IVRLP protocols may not effectively penetrate wound beds as clinicians assume, raising important questions about whether this technique meaningfully influences outcomes in naturally occurring infections or whether alternative routes of administration and timing protocols warrant investigation.
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Practical Takeaways
- •IVRLP via cephalic vein may not reliably deliver antibiotics to distal limb wounds — consider alternative perfusion routes or delivery methods for infected distal limb injuries
- •Palmar digital vein perfusion showed better dye distribution than cephalic vein, suggesting route of administration significantly affects drug delivery to the wound bed
- •Do not rely on standard IVRLP protocols with cephalic vein access to control S. aureus bioburden in experimental wound infections
Key Findings
- •IVRLP with amikacin did not reduce S. aureus bioburden compared to control limbs at any time point (days 2, 5, or 8 post-wounding)
- •Methylene blue dye was visible in all tissues after palmar digital vein perfusion but absent after cephalic vein perfusion, suggesting inadequate drug delivery via cephalic route
- •No difference in frequency of positive bacterial growth between treated and control limbs across all sampling periods