Detection of the antibacterial activity of chitosan

Using three bacterial strains the antibacterial activity of Chitoskin (R), a chitosan-containing wound-dressing, was investigated by determining the viable bacterial cell count in liquid cultures in the absence and presence of Chitoskin (R). Results were compared to those obtained for cellulose and silver-laminated cellulose. While the pure cellulose wound-dressing had no impact on the bacterial growth, Chitoskin (R) and, to an even greater extend, silver-laminated cellulose reduced the viable cell count over 4,5 hrs. Adding a second sample after 2 hrs of incubation resulted in a significantly increased activity of Chitoskin (R). In the presence of protein the activity of the silver-laminated cellulose was completely abolished, while that of Chitoskin (R) continued for at least 3 hrs. Covering bacterial cells on an agar plate with Chitoskin (R) reversibly inhibited their growth, but did not kill them. Instead, they could be transferred to another sterile agar plate. The results are compatible with the hypothesis that Chitoskin (R) shows a bacteriostatic activity due to its ability to strongly adsorb the cells. From the theoretical point of view, heavily contaminated wounds would benefit from an early renewal of the wound dressing.