Abstract To date very little studies are available
in the literature on the interaction of Al2O3 nanoparticles
with multidrug-resistant strains of Staphylococcus
aureus. Considering the paucity of earlier
reports the objective of present study was to
investigate the antibacterial activity of Al2O3 NPs
(50 nm) against methicillin-resistant S. aureus and
methicillin-resistant coagulase negative staphylococci
by various methods. Al2O3 NPs were characterized
by scanning electron microscopy, highresolution
transmission electron microscopy, and
X-ray diffraction. The MIC was found to be in the
range of 1,700–3,400 lg/ml. Almost no growth was
observed at 2,000 lg/ml for up to 10 h. SEM
micrograph revealed that the treated cells were
significantly damaged, showed indentation on cell
surface and clusters of NPs on bacterial cell wall.
HR-TEM micrograph shows disruption and disorganization
of cell membrane and cell wall. The cell
membrane was extensively damaged and, most
probably, the intracellular content has leaked out.
Al2O3 NPs not only adhered at the surface of cell
membrane, but also penetrated inside the bacterial
cells, cause formation of irregular-shaped pits and
perforation on their surfaces and may also interact
with the cellular macromolecules causing adverse
effect including cell death. The data presented here
are novel in that Al2O3 NPs are effective bactericidal
agents regardless of the drug resistance
mechanisms that confer importance to these bacteria
as an emergent pathogen. Therefore, in depth studies
regarding the interaction of Al2O3 NPs with cells,
tissues, and organs as well as the optimum dose
required to produce therapeutic effects need to be
ascertained before we can expect a more meaningful
role of the Al2O3 NPs in medical application.