Kit with technetium‐99m labelled antimicrobial peptide UBI 29‐41 for specific infection detection

Abstract

Abstract The purpose of this study was to investigate radiochemical and biological characteristics of an instant kit for the preparation of 99m Tc‐labelled UBI 29‐41 for specific detection of infections. The kit is based on 99m Tc‐labelling via HYNIC conjugated to the terminal amine of the peptide, producing a well‐understood labelled compound. One hour after the addition of fresh 99m TcO to the kit ITLC and HPLC reverse‐phase analysis was performed. Stability of the labelled complex was challenged and the binding to bacterial pellets was assessed. Finally, the biodistribution and accumulation in MRSA ‐infected tissues were studied using scintigraphy and ex vivo countings. Data were compared to a non‐kit control method. Radiochemical analysis indicated >96% labelling, stability for 24 h and the preparation was used without purification. In vitro studies showed 41% of radioactivity was bound to bacteria. After injection into mice with a bacterial infection the site of infection was visualized within 30 min. Kit prepared 99m Tc‐HYNIC‐UBI 29‐41 was rapidly (half‐life 113 min) cleared via the kidneys and urinary bladder, essentially slower than control peptide (half‐life 74 min). This slower clearance results in higher activities in blood and other tissues. Nevertheless, 99m Tc‐HYNIC‐UBI 29‐41 shows favourable radiochemical characteristics and deserves further evaluation in a clinical setting. Copyright © 2005 John Wiley & Sons, Ltd.