INTRACELLULAR-DISTRIBUTION OF AMPICILLIN IN MURINE MACROPHAGES INFECTED WITH SALMONELLA-TYPHIMURIUM AND TREATED WITH (H-3)AMPICILLIN-LOADEDNANOPARTICLES

The intracellular distribution of (H-3)ampicillin-loaded polyisohexylc yanoacrylate nanoparticles was studied in murine macrophages (peritone al cells and the J774 cell line) infected by Salmonella typhimurium C5 , using ultrastructural autoradiography. Ampicillin penetration and re tention into the cells obviously increased by means of nanoparticles. After short-term (2-4h) treatment with the nanoparticle formulation, n umerous intracellular bacteria were seen to be in the process of destr uction. The tritium labelling was located in the cell cytoplasm and in side vacuoles in which bacteria undergoing degradation were often pres ent. After long-term (12h) treatment, numerous spherical bodies (d: 10 0 nm to 500 nm) and larger forms (2 mu m) were seen in the vacuoles. R adioactivity was mainly found to be localized on the spherical bodies, indicating marked damaging action of the ampicillin on the bacterial walls. The targeting of ampicillin therefore allowed its penetration i nto the macrophages and vacuoles infected with S. typhimurium.