Evaluation of [67Ga]Citrate in The Detection of Various Microorganism Infections in Animal Models

Gallium-67 citrate has been known as a good infection agent in nuclear medicine for decades. In this work the value of 67Ga-citrate has been investigated in infected animal models using SPECT imaging at optimized/standardized conditions. The bacterial (Staphylococcus aureus; S.a. and Escherichia coli; E.c.) and fungal (Candidae albicans; C.a.) species from standard sources were cultured according to the standard procedures and wild-type NMRI rats were inoculated by the injection of 5x107 microorganisms (MO) into their thighs and animals incubated for infection site formation for 2 and 3 days followed by iv injection of freshly prepared 67Ga-citrate (45-50 µCi) and SPECT imaging performed at 2, 4 and 24 hours post injection in parallel with control groups. In S.a.-infected rats 67Ga-citrate demonstrated hot spot foci at all time intervals esp. 24h post injections in contrast with normal animal scans. In case of C.a., the infected animals also demonstrated significant accumulation foci being most significant after 24h. In E.c.-infected animals however weak positive scans were obtained even after 24 hours. Our animal models developed for the evaluation of new infection-targeting agents were successfully positive using 67Ga scan. These models can also be used in the evaluation of newly developed antibiotics in animal models for in vivo studies. The efficacy of 67Ga-scan in our microorganism infection models can be summarized as S.A.>C.a.>E.c..