Intramuscular Antibiotics Modify Infectious Outcomes in Contaminated, Ischemic Limbs

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.

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.

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).

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.