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Intramuscular Antibiotics Modify Infectious Outcomes in Contaminated, Ischemic Limbs
Michaela Hall1,2, Savannah Walker3, Brian France4
1174th Medical Group, 174th Attack Wing Hancock Field Air National Guard Base, Syracuse, NY 13211, United States.
Introduction:
Tourniquets are sometimes necessary for hemorrhage control in the setting of traumatic limb injuries but may increase the risk of ischemic complications, including infection and impaired wound healing. Antibiotics may help to reduce infection rates in combat-associated injuries; however, intravenous access is not always readily available, particularly in austere environments. This study evaluates the effect of ertapenem administered intramuscularly at the tourniquet site on infection rates in a 24-hour porcine contaminated wound model.
Materials And Methods:
Yorkshire pigs (n = 12; 33.6 ± 1.4 kg) were anesthetized. A crush laceration injury was created in the ventral forelimb and inoculated with Staphylococcus aureus (SA) and Klebsiella pneumoniae (KP). Subsequently, a tourniquet was applied for 4 hours. Pigs were randomized into a Control group (n = 6) receiving 1% lidocaine and an Ertapenem group (n = 6) receiving 1% lidocaine and Ertapenem, both administered intramuscularly at the tourniquet site. Hemodynamics and respiratory parameters were monitored continuously for 24 hours, and resuscitation was administered according to critical care guidelines. Wound cultures and histopathology were obtained at baseline, and 4 and 24 hours post-injury.
Results:
No animal in either group grew SA or KP in the wound at baseline. At 4 and 24 hours, deep tissue cultures from all Control animals (100%, n = 6) were positive for both SA and KP. In the Ertapenem group, SA was detected in deep tissue cultures in 50% of animals (n = 3) at 4 hours (P = .046 vs. Control) and 33% (n = 2) at 24 hours (P = .014 vs. Control). KP was present in 33% of Ertapenem animals (n = 2) at both 4 and 24 hours (P = .014 vs. Control).
Conclusions:
Ertapenem administered intramuscularly at the tourniquet site in a contaminated crush laceration with ischemia reduced the rates of SA and KP infection by 67%. Intramuscular antibiotic delivery with tourniquet placement represents a potential therapy for combat-related injuries to reduce infectious complications.
Insights
Intramuscular ertapenem at tourniquet sites significantly reduced infection rates in a porcine wound model. This localized antibiotic delivery offers a promising strategy for combat injuries, mitigating complications from hemorrhage control.
Area of Science:
- Trauma and Emergency Medicine
- Infectious Disease Research
- Pharmacology
Background:
- Tourniquets are vital for hemorrhage control in limb trauma but risk ischemic complications like infection.
- Intravenous antibiotic access is often limited in austere environments, complicating infection prevention.
- This study investigates intramuscular ertapenem at the tourniquet site to combat infection in contaminated wounds.
Purpose of the Study:
- To evaluate the efficacy of intramuscular ertapenem administered at the tourniquet site.
- To assess the impact on bacterial infection rates in a porcine model of contaminated crush laceration with ischemia.
- To determine the feasibility of localized antibiotic delivery in resource-limited settings.
Main Methods:
- A 24-hour porcine model with simulated crush laceration and bacterial inoculation (Staphylococcus aureus and Klebsiella pneumoniae).
- Tourniquet application for 4 hours, followed by intramuscular administration of either lidocaine (Control) or lidocaine with ertapenem.
- Continuous hemodynamic monitoring, wound cultures, and histopathology at multiple time points.
Main Results:
- Control group showed 100% deep tissue infection with both bacteria at 4 and 24 hours.
- Ertapenem group demonstrated a significant reduction in bacterial presence: Staphylococcus aureus in 50% (4h) and 33% (24h), Klebsiella pneumoniae in 33% (4h & 24h).
- Statistically significant differences (P < .05) in infection rates were observed between groups.
Conclusions:
- Intramuscular ertapenem at the tourniquet site effectively reduced bacterial infection rates by 67% in a contaminated, ischemic wound model.
- Localized antibiotic delivery via intramuscular injection alongside tourniquet application is a viable strategy.
- This approach holds potential for preventing infectious complications in combat-related injuries.
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