Ultrahigh antibacterial efficacy of meropenem-loaded chitosan nanoparticles in a septic animal model

Antimicrobial resistance is one of the most significant health challenges worldwide. Meropenem is a broad spectrum beta-lactam antibiotic that possesses high activity against Gram-positive and Gram-negative bacteria. However, it has a short plasma half-life, and thus requiring frequent administration of high doses. For the first time, meropenem-loaded chitosan nanoparticles were prepared and evaluated as a potential tool to overcome antimicrobial resistance and to improve pharmacokinetics of the drug. Spherical nanosized particles were prepared and demonstrated ultrahigh encapsulation efficiency of meropenem (i.e. 76.3%). The nanoparticles could be stored in a freeze-dried powdered form while maintaining their physicochemical characteristics. In vitro, higher antibacterial activities of the drug-loaded nanoparticles were observed against methicillin-sensitive and methicillin-resistant Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae, as compared to the free drug. The nanoparticles were then tested in a septic rat model of Klebsiella pneumoniae and showed exceptional improvement of survival and bacterial clearance, as compared to the animals treated with the free drug. Hence, meropenem-loaded chitosan nanoparticles might have great potential for overcoming antimicrobial resistance.