| Summary: | 碩士 === 國立臺灣大學 === 農業化學研究所 === 90 === Pseudomonas aeruginosa is an opportunistic pathogen that can cacuse serious nosocomial infections especially in immuno -compromised hosts, cystic fibrosis and severe burned patients. When the biofilms form, they will increase 500~1000 times of resistance against antimicrobial agents in comparision with its planktonic counter parts. One explanation to their recalcitrance is that the insoluble extracellular polymers (EPS) of biofilm offer a physical barrier to prevent cells from directly interactig with chemical biocides and antibiotics. In this study, two kinds of bismuth thiols: bismuth dimercaprol (BisBAL) and bismuth β-mercaptolethanol (BisβME) were applied to investigate the different formation stages of P. aeruginosa biofilm formation on the inhibitive effect of polysaccharide production in response to antimicrobial treatment. The results showed that treatment of 1×MIC BisBAL and BisβME for 24h at early stage of biofilm accumulation phase reduced 43%、48％ EPS production, but no inhibition was found at late stage. Increasing the treating time of BisBAL or BisβME up to 72h against early stage biofilm did not enhace inhibitive effect of EPS. There was 64% reduction in EPS production when treated by 4×MIC of BisBAL to 8h-old biofilm, but treated with 4×MIC BisβME at early stage, no futher inhibitive effect of EPS was found. Combining 1×MIC BisBAL with 1×MIC kanamycin showed significant synergy when biofilms were treated at 16h old. The survial ratio droped from (0.84±0.19) to (0.10±0.06). We demonstrated that BisBAL and BisβME could inhibit EPS production at early stage of P.aeruginosa biofilm and BisBAL could enhance the antimicrobial activity of kanamycin.
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