Monitorization of Staphylococcus aureus infection in mice by PET image

Trabajo presentado en el 5th Congress of European Microbiologists, celebrado en Leipzig (Alemania) del 21 al 25 de julio de 2013.
Staphylococcus aureus biofilms cause persistent chronic infections that require repeated antibiotic treatments at high doses. A major limitation to evaluate new bacterial biofilm treatments is the in vivo animal models available. Positron emission tomography (PET) using 18FluoroDeoxyGlucose (18FDG) has been widely used in cancer diagnosis, since the tumoral transformation usually increases the expression of glucose transporter and glycolytic enzymes. The aim of this work was to evaluate the feasibility of 18FDG-PET imaging for in vivo monitoring of bacterial biofilm infections in mice. For this, sealed catheters of VialonTM biomaterial were pre-colonized with Staphylococcus aureus ATCC15981, and subcutaneously implanted in mice (n=5). The in vivo infections were monitored at days 1, 7 and 14 post-infection, in a micro-PET scanner (Mosaic, Philips), 1 hour after intravenous injection of 18FDG. Images were quantitatively analysed by means of Standardized Uptake Value (SUV60) index. In parallel, the number of CFU/catheter and lesions induced by the infected catheter were determined. Similarly, the usefulness of this mouse model was assessed, after oral treatment with rifampin. SUV60 indexes were calculated in the catheter area and in the regional lymph nodes, associated to high number of both bacteria and PMN cells around the catheter. After antibiotic treatment, both SUV60 index and CFU/catheter decreased drastically, and lymph node images became negative. In conclusion, this study represents an advance for the in vivo monitoring of biofilm infections and follow-up evaluation of the efficacy of antibiotic therapies in living mice.