Antibacterial activity of lysozyme-chitosan oligosaccharide conjugates (LYZOX) against Pseudomonas aeruginosa, Acinetobacter baumannii and Methicillin-resistant Staphylococcus aureus

Abstract

The recent emergence of antibiotic-resistant bacteria requires the development of new antibiotics or new agents capable of enhancing antibiotic activity. This study evaluated the antibacterial activity of lysozyme-chitosan oligosaccharide conjugates (LYZOX) against Pseudomonas aeruginosa , Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus (MRSA), which should resolve the problem of antibiotic-resistant bacteria. Bactericidal tests showed that LYZOX killed 50% more P . aeruginosa (NBRC 13275), A . baumannii and MRSA than the control treatment after 60 min. In addition, LYZOX was shown to inhibit the growth of P . aeruginosa (NBRC 13275 and PAO1), A . baumannii and MRSA better than its components. To elucidate the antibacterial mechanism of LYZOX, we performed cell membrane integrity assays, N-phenyl-1-naphthylamine assays, 2-nitrophenyl β-D-galactopyranoside assays and confocal laser scanning microscopy. These results showed that LYZOX affected bacterial cell walls and increased the permeability of the outer membrane and the plasma membrane. Furthermore, each type of bacteria treated with LYZOX was observed by electron microscopy. Electron micrographs revealed that these bacteria had the morphological features of both lysozyme-treated and chitosan oligosaccharide-treated bacteria and that LYZOX destroyed bacterial cell walls, which caused the release of intracellular contents from cells. An acquired drug resistance test revealed that these bacteria were not able to acquire resistance to LYZOX. The hemolytic toxicity test demonstrated the low hemolytic activity of LYZOX. In conclusion, LYZOX exhibited antibacterial activity and low drug resistance in the presence of P . aeruginosa , A . baumannii and MRSA and showed low hemolytic toxicity. LYZOX affected bacterial membranes, leading to membrane disruption and the release of intracellular contents and consequent bacterial cell death. LYZOX may serve as a novel candidate drug that could be used for the control of refractory infections.

Bioactive Secondary Metabolites from Trichoderma spp. against Phytopathogenic Bacteria and Root-Knot Nematode

“…Others are responsible for membrane disruption [59] and inhibition of cell wall and nucleic acid synthesis [60,61]. Lysosime affects bacterial cell walls and the cell membrane, leading to membrane disruption and the release of intracellular contents and consequent bacterial cell death [62]. These mechanisms of action are consistent with our SEM studies.…”

Preparation and Antimicrobial Activity of Chitosan and Its Derivatives: A Concise Review

“…represent a serious threat, due to its remarkable ability to acquire resistance and to the rapid spread of resistant strains in the hospital environment [ 69 ]. Saito et al obtained lysozyme–chitosan oligosaccharides conjugates with good antibacterial activity against P. aeruginosa , A. baumannii and MRSA [ 69 ]. Further studies using multidrug resistant clinical isolates of A. baumannii would be of great interest.…”

Antimicrobial Chitosan Conjugates: Current Synthetic Strategies and Potential Applications

“…Examples include the Maillard reaction [106], acid-base salt formation reaction [36], and electrochemical reaction [107]. For instance, the Maillard reaction is commonly used for the coupling of xylan [108], polylysine [109], and lysozyme [47,106,110] with chitosan. The Maillard reaction is a non-enzymatic browning reaction, which occurs between the ε-amino group in a protein and the reducing carbonyl group in a polysaccharide upon heating.…”