Detection of acute bacterial infection within soft tissue injuries using a 99mTc-labeled chemotactic peptide.

OBJECTIVE

Infection imaging with a 99mTc-labeled chemotactic peptide was evaluated in a rabbit model of Escherichia coli infections in burned tissue.

MATERIALS AND METHODS

The peptide was radiolabeled with 99mTc via the hydrazino nicotinamide derivative. Three groups of six animals were studied: (group A) unilateral infected burns; (group B) bilateral burns with unilateral infection; and (group C) uninfected burns. Twenty-four hours after injury, groups A and B were infected, and 8 hours later, all animals were injected with approximately 0.50 mCi of 99mTc-peptide.

MEASUREMENTS AND MAIN RESULTS

In groups A and B, excellent images of the infections were obtained at 3 to 4 and 16 to 18 hours after injection of the peptide. At 3 to 4 hours after injection, the target-to-background ratios (T/B) were 3.12 +/- 0.28 for group A and 4.33 +/- 0.61 for group B (p = n.s.). At 16 to 18 hours, the T/B ratios increased significantly (p < 0.01): group A = 8.10 +/- 1.03 and B = 7.70 +/- 1.25. The T/B ratio for group C was only slightly greater than unity.

CONCLUSIONS

These results indicate that 99mTc-labeled chemotactic peptides are effective radiopharmaceuticals for the rapid detection of focal sites of infection within thermally injured tissues.