For new bacterial suspensions of E. coli and S. aureus prepa- ration, the aliquots of E. coli and S. aureus stored at −21 °C were first rehydrated separately in LB medium for 3 h at 37 °C under constant stirring (110 rpm). The rehydrated aliquots were im- merged individually into fresh LB medium (5% v/v) and incubated at 37 °C for 16 h until reaching the stationary bacterial growth phase [12] . Subsequently, the cultivated bacteria were collected by centrifugation for 10 min at 12 °C with 40 0 0 rpm. The recov- ered pellets were washed at least three times under the same conditions (40 0 0 rpm centrifugation for 10 min at 12 °C) using the stroke-physiological saline solution and the nutrient can be removed for avoiding the bacterial development, prior to the bactericidal test. After centrifugation, the washed bacterial pellets were suspended separately in stroke-physiological saline solution, the absorbance of the suspensions were measured at 600 nm to determine the bacterial concentration, according to calibration curves previously obtained. Finally, bacterial cells were diluted by a double dilution method, in order to obtain a bacterial suspension with 10 6 CFU/mL cell concentration.