Synergistic antibacterial effect of Bi2S3 nanospheres combined with ineffective antibiotic gentamicin against methicillin-resistant Staphylococcus aureus

Abstract

In this paper, Bi₂S₃ nanospheres with size of 212nm were prepared by a simple hydrothermal process. The selectively enhanced antibacterial effects of Bi₂S₃ nanospheres with three classes of ineffective antibiotics, β-lactam (cefuroxime, CXM; cefotaxime, CTX and piperacillin, PIP), quinolone (ciprofloxacin, CIP) and aminoglycoside (gentamicin, GEN) against clinical isolated methicillin-resistant Staphylococcus aureus (MRSA) were investigated for the first time. GEN shows significantly synergistic growth inhibition against MRSA when combined with Bi₂S₃ nanospheres, while CXM, CTX, PIP and CIP do not. Raman spectroscopy and Z potential studies reveal that Bi₂S₃ could interact with GEN and the combination showed small electronegativity, which probably induced the increase of GEN content in cytoplasm of bacteria. Furthermore, the combination of Bi₂S₃ nanospheres and GEN can destroy the bacterial membrane function and induce more bactericidal reactive oxygen generation than that of Bi₂S₃ or GEN alone. The cytotoxicity test indicates that the combination of Bi₂S₃ and GEN presented low toxicity to human normal hepatocyte L02. This work shows that Bi₂S₃ nanospheres can be used to enhance the action of ineffective antibiotic GEN against MRSA, thus strengthening the antibiotic capacity for fighting MRSA infections.

Keywords: Bi(2)S(3) nanospheres; Gentamicin; MRSA; Mechanism; Synergistic antibacterial effect.