Protease activity of cell-free supernatants from Pseudomonas aeruginosa grown in the presence and the absence of azithromycin. MMPsense 750 FAST was added to supernatants from VR1 and VR2 strains grown in presence or absence of AZM (SnVR1 ± AZM and SnVR2 ± AZM) concentrated 1X, 10X and 30X. IVIS imaging system has been used to quantify the time course of the fluorescence. Data were expressed as induction folds over baseline (bacterial growth medium TSB). Results are reported as mean ± SEM and significance attributed when P < 0.05 (*) or P < 0.01 (**).