Effects of zinc oxide on the attachment of Staphylococcus aureus strains

Abstract We examined the attachment of Staphylococcus aureus to plastic tissue-culture coverslips after incubation for 24 h. The attachment to coverslips was weaker in rabbit plasma with 5% zinc oxide (ZnO) than in the control rabbit plasma without ZnO ( P S. aureus strains was not detected in plasma with 5% ZnO after incubation for 24 h. The membranous structure (an immature biofilm) was formed on the coverslips by S. aureus cells in plasma after incubation for 24 h. The colony counts of S. aureus cells on the membranous structures were lower in plasma with 5% ZnO, plasma with 0.2% hinokitiol, plasma with 5% ZnO+0.2% hinokitiol, plasma with cefdinir at 4 minimum inhibitory concentration (MIC) and plasma with levofloxacin at 4 MIC, than in the control plasma after incubation for 24 h ( P P S. aureus strains peaked at an MIC distribution of 16–32 μ g/ml. The peak shifted to below 1 μ g/ml by adding 5% ZnO in agar plate method. The results suggest that the attachment of S. aureus cells to the coverslips is suppressed in the presence of 5% ZnO and that antistaphylococcal activities of cefdinir, levofloxacin and hinokitiol increase in the presence of 5% ZnO.