To elucidate the antibacterial mechanisms of the ceramics magnesium oxide (MgO), calcium oxide (CaO) and zinc oxide (ZnO), damage to bacteria caused by these powder slurries are studied on the basis of change insensitivities to antibiotics, of which the primary inhibitory actions are understood well. Four kinds of antibiotics, penicillin G, chloramphenicol, nalidixic acid and rifampicin, were used as the selective reagents. The MgO and CaO powder slurries increased the sensitivities of Escherichia coli to rifampicin and chloramphenicol. Though the MgO and CaO powder slurries have high pH values, changes in the sensitivities by the MgO and CaO powder slurries were obviously different from those via alkaline treatment. The ZnO powder slurry enhanced the sensitivity of the E. coli to chloramphenicol. This result suggests that the antibacterial actions of MgO and CaO powder slurries were different from those of ZnO powder slurry.
1997 The Society of Chemical Engineers, Japan