Efficacy of tetracycline encapsulated O-carboxymethyl chitosan nanoparticles against intracellular infections of Staphylococcus aureus.

Intracellular bacterial infections are recurrent, persistent and are difficult to treat because of poor penetration and limited availability of antibiotics within macrophages and epithelial cells. We developed biocompatible, 200 nm sized tetracycline encapsulated O-carboxymethyl chitosan nanoparticles (Tet-O-CMC Nps) via ionic gelation for its sustained delivery of Tet into cells. S. aureus binds and aggregates with Tet-O-CMC Nps increasing drug concentrations at the infection site. Tet-O-CMC Nps were sixfold more effective in killing intracellular S. aureus compared to Tet alone in HEK-293 and differentiated THP1 macrophage cells proving it to be an efficient nanomedicine to treat intracellular S. aureus infections.