Screening Bactericidal Action of Cytoplasm Extract from Kumazasa Bamboo (Sasa veitchii) Leaf against Antibiotics- Resistant Pathogens such as MRSA and VRE Strains

Abstract

We aimed to develop a new treatment against antibi- otic-resistant bacteria by focusing on cytoplasm of Kumazasa bamboo leaf. The cytoplasmic extract displ ays potent bactericidal action against Gram-positive ba cte- ria such as Staphylococcus aureus, Enterococci and Strep- tococcus pneumoniae and also multi-antibiotic resis tant MRSA (methicillin-resistant Staphylococcus aureus) and VRE (vancomycin-resistant Enterococci) strains. It in- duced bacteriolysis by firmly aggregating MSSA (me- thicillin-susceptible Staphylococcus aureus) and MR SA, and by lysis of VSE (vancomycin-susceptible Entero- cocci) and VRE. Clinical isolates of MRSA (30 strai ns in total) were susceptible to this extract, which g ave MICs of Kumazasa-cytoplasmic extract ranging from 1.6 to 6.3%. The antibacterial action was bactericidal on scan- ning electron microscopy (SEM) analysis. A synergis tic effect of this extract with ampicillin (ABPC) was obvi- ously observed in all MRSA strains. The synergistic ef- fect with vancomycin (VCM) was observed against VRE . The combination with clarithromycin (CAM) or tetrac y- cline (TC) additively enhanced the antibacterial ac tivity of CAM against CAM-susceptible Enterococci strains, and also that of TC against TC-resistant VRE strain s. The present results should encourage research on an ti- bacterial–hydrophilic ingredients derived from Kuma zasa for use against antibiotic-resistant bacteria. The combi- nation of Kumazasa-cytoplasmic extract with a cell wall synthesis inhibitor (ABPC or VCM) will be a highly ef- ficient treatment for infections caused by multidru g-re- sistant MRSA and VRE strains