Application of [^99mTc]Tc-GSA in the diagnosis of Staphylococcus aureus infections

Staphylococcus aureus can cause a variety of conditions such as bacteremia, sepsis, toxic shock syndrome, pneumonia, and infective endocarditis; therefore, a rapid and accurate diagnosis should be made to pinpoint the site of infection. This study aimed to use the existing nuclear medicine tracer [^99mTc]Tc-dimercaptosuccinic acid galactosyl human serum albumin ([^99mTc]Tc-GSA) as a simple technique for the early diagnosis of S. aureus infection.

The in vitro studies evaluated the accumulation of [^99mTc]Tc-GSA in S. aureus. In addition, the effect of metabolic and vital activity and inhibition of asialoglycoprotein receptors on [^99mTc]Tc-GSA accumulation were evaluated. In vivo studies were performed on the biodistribution and imaging of [^99mTc]Tc-GSA in the S. aureus SR3637 mouse thigh infection model.

In vitro studies have confirmed that [^99mTc]Tc-GSA accumulates to the same extent as 2-deoxy-2-[¹⁸F]fluoro-d-glucose, and it was thought that [^99mTc]Tc-GSA binds to the receptors that recognize the saccharide molecules and glycan chains expressed in S. aureus. In addition, in the distribution and imaging of [^99mTc]Tc-GSA, it was confirmed that the latter accumulates at the infection site and shows a clear contrast with the non-infected site.

The application of [^99mTc]Tc-GSA to the imaging diagnosis of S. aureus infection is expected to non-invasively detect the localization of S. aureus in real time, pinpoint the site of infection and determine the number of viable bacteria, and help in the selection of optimal therapeutic agents and treatments.