Effect of nanoparticle-bound ampicillin on the survival of Listeria monocytogenes in mouse peritoneal macrophages.

The efficacy of ampicillin bound to polyisohexylcyanoacrylate nanoparticles was studied in vitro in mouse peritoneal macrophages infected with Listeria monocytogenes. Nanoparticles containing ampicillin 1 mg/L were more effective after 30 h than free ampicillin at the same concentration, with viable counts of 3.68 and 5.43 log10 cfu/mL, respectively. The nanoparticles acted on the intracellular bacteria after a lag period of 6-9 h; this time was apparently required for the degradation of the polymer. At the doses used in these experiments, empty nanoparticles had neither an anti-listeria nor a cytotoxic effect.