Microstructural, physico-chemical, antibacterial and antibiofilm efficacy of imipenem loaded chitosan nano-carrier systems to eradicate multidrug resistant Acinetobacter baumannii

Abstract

Acinetobacter baumannii, being labelled as “critical priority pathogen” is a major threat faced by humanity nowadays as it is responsible for numerous life-threatening nosocomial infections. A. baumannii is a highly resistant microbe that forms biofilms at infection site thus interfering with the permeability of antibiotics. Therefore, intrinsically antibacterial biopolymer, chitosan, is utilized to synthesize imipenem (IPM) encapsulated chitosan nano-carrier system (CS-IPM-NCS) against multidrug resistant A. baumannii (MDRAB). CS-IPM-NCS were fabricated using ionic gelation method. The developed CS-IPM-NCSs were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), zeta potential, average size and Fourier transform infrared (FTIR) spectroscopy. It was observed that SEM and AFM analyses revealed smooth, regular and homogeneously distributed nano-carrier systems. The mean size of CS-IPM-NCS was found to be < 100 nm and the zeta potential was 38.9 ± 5.52 mV that indicated the stability of the nano-carrier systems. Encapsulation efficiency was optimized to ensure high encapsulation (87 ± 3%) of IPM in 0.3% (w/v) CS-NCS. Changes in characteristic peaks in FTIR spectra demonstrated the successful encapsulation of IPM inside the CS-NCS. The antibacterial activity of CS-IPM-NCS was evaluated by growth kinetics assay and the results exhibited potent (100%) inhibition of MDRAB. The outcome of CS-IPM-NCS on the pre-formed biofilms by MDRAB strains were ∼90%, due to the cationic-anionic interaction between NCS and biofilm structures. Thus, the present study findings suggest that CS-IPM-NCS might be an alternative strategy to conventional (failing) antibiotics to eradicate MDRAB.