Differentiation Between Responders and Non-Responders to Antibiotic Treatment in Mice Using...

Bacterial infection causes significant mortality and morbidity worldwide despite the availability of antibiotics. Differentiation between responders and non-responders early on during antibiotic treatment will be informative to patients and healthcare providers. Our objective was to investigate whether PET imaging with ¹⁸F-Fluorodeoxysorbitol (¹⁸F-FDS) or ¹⁸F-FDG can be used to differentiate responders from non-responders to antibiotic treatment.

NTUH-K2044 was used for infection in Albino C57 female mice. Each mouse was inoculated intratracheally with NTUH-K2044 to induce lung infection (n = 8). For treatment studies, two bacterial doses for animal inoculation and two treatment starting times were compared to optimize treatment profiles. ¹⁸F-FDS or ⁸F-FDG /PET imaging was performed to monitor treatment progression.

Our results demonstrated that the treatment profiles for mice infected with 25 CFU hvKp and antibiotic treatment starting at 24 p.i. were not ideal due to no evidence of lung infection and lack of treatment efficacy. The optimal scheme is to use 250 CUF for infection and start antibiotic treatment at 24 h p.i. to monitor antimicrobial efficacy. 75% of the mice were classified as responders to antibiotic treatment. 25% of the mice were classified as non-responders. ¹⁸F-FDG was used to compare with ¹⁸F-FDS, but all mice showed increased lung uptake of ¹⁸F-FDG during 3-day treatments.

¹⁸F-FDS is a promising PET tracer to image bacterial infection. It can be used to monitor response to treatment, and differentiate responders from non-responders to antibiotic treatment, but ¹⁸F-FDG cannot, probably due to the presence of high degree of inflammation before and after treatment.