Non invasive real-time monitoring of bacterial infection & therapeutic effect of anti-microbials in five mouse models

BACKGROUND & OBJECTIVES: In vivo imaging system has contributed significantly to the understanding of bacterial infection and efficacy of drugs in animal model. We report five rapid, reproducible, and non invasive murine pulmonary infection, skin and soft tissue infection, sepsis, and meningitis models using Xenogen bioluminescent strains and specialized in vivo imaging system (IVIS). METHODS: The progression of bacterial infection in different target organs was evaluated by the photon intensity and target organ bacterial counts. Genetically engineered bioluminescent bacterial strains viz. Staphylococcus aureus Xen 8.1, 29 and 31; Streptococcus pneumoniae Xen 9 and 10 and Pseudomonas aeruginosa Xen-5 were used to induce different target organs infection and were validated with commercially available antibiotics. RESULTS: The lower limit of detection of colony forming unit (cfu) was 1.7-log(10) whereas the lower limit of detection of relative light unit (RLU) was 4.2-log(10). Recovery of live bacteria from different target organs showed that the bioluminescent signal correlated to the live bacterial count. INTERPRETATION & CONCLUSIONS: This study demonstrated the real time monitoring and non-invasive analysis of progression of infection and pharmacological efficacy of drugs. These models may be useful for pre-clinical discovery of new antibiotics.