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目的 探讨lycosin-Ⅰ对铜绿假单胞菌的体外抗菌活性.方法 随机收集中南大学湘雅二医院铜绿假单胞菌临床分离株,其中铜绿假单胞菌的多重耐药菌10株,非耐药菌10株.应用微量肉汤稀释法检测lycosin-Ⅰ对铜绿假单胞菌的体外最低抑菌浓度(MIC);选取铜绿假单胞菌的多重耐药菌的代表株Isolate 8(MIC为8μg/mL)和非耐药菌的代表株Isolate 12(MIC为8 μg/mL),检测4×MIC浓度lycosin-Ⅰ的杀菌动力学;体外构建适宜环境,培养代表株24 h,定点测定其600 nm处吸光度并绘制生长曲线;在培养环境中分别添加5 mmol/L钙离子或镁离子,检测lycosin-Ⅰ杀菌能力的盐耐受性.结果 Lycosin-Ⅰ在体外条件下对铜绿假单胞菌的多重耐药菌和非耐药菌均表现出良好的体外抗菌活性:lycosin-Ⅰ抗铜绿假单胞菌多重耐药菌的MIC为12(8,32) μg/mL,非耐药菌的MIC为12(8,32) μg/mL,两组MIC差异无统计学意义(U=42,P＞0.05).4×MIC浓度的lycosin-Ⅰ在60 min时即可杀灭约50％的铜绿假单胞菌多重耐药菌和非耐药菌.体外培养24 h,可见在MIC以下浓度(0,2,4μg/mL) lycosin-Ⅰ干预下铜绿假单胞菌多重耐药菌和非耐药菌于6～16h快速生长,18 h后生长速度趋于平缓;在MIC浓度(8μg/mL) lycosin-Ⅰ干预下,细菌均难以生长.5 mmoL/L Ca2+或Mg2+可以减弱lycosin-Ⅰ的体外抗菌活性,Ca2+的加入使lycosin-Ⅰ抗铜绿假单胞菌的多重耐药菌和非耐药菌的MIC值均由原来的8 μg/mL升高至64 μg/mL,Mg2+的加入则均使MIC值由原来的8 μg/mL升高至32 μg/mL.但是当lycosin-Ⅰ处于较高浓度状态(＞64 μg/mL或＞32 μg/mL)时,其仍然可以保持较好的抗铜绿假单胞菌多重耐药菌和非耐药菌活性.结论 Lycosin-Ⅰ在体外条件下可以有效抑制铜绿假单胞菌浮游菌的生长,具有一定的盐耐受性,有望发展成为一种新型抗菌药物.“,”Objective To investigate the in vitro antibacterial activity of lycosin-Ⅰ against clinical isolates of Pseudomonas aeruginosa.Methods The clinical isolates of Pseudomonas aeruginosa,including 10 strains of multidrug resistant Pseudomonas aeruginosa and 10 strains of non-multidrug resistant Pseudomonas aeruginosa,were randomly collected from the Second Xiangya Hospital of Central South University.The in vitro minimum inhibitory concentrations (MIC) of lycosin-Ⅰ against Pseudomonas aeruginosa were detected by the broth microdilution method.The representative isolates of multidrug resistant (Isolate 8,MIC =8 μg/mL) and non-multidrug resistant (Isolate 12,MIC =8 μg/mL) Pseudomonas aeruginosa were selected,and the bactericidal kinetics of 4 × MIC concentration of lycosin-Ⅰ against them were determined.After the representative isolates were cultured with suitable medium for 24 hours,the absorbency of 600 nm was detected and the growth curve was drawn.Five mmol/L of Ca2+ or Mg2+ were added into the medium to investigate the salt tolerance of lycosin-Ⅰ.Results Lycosin-Ⅰ in vitro showed good antibacterial activity against both multidrug resistant and non-multidrug resistant Pseudomonas aeruginosa.The MICs (median [P25,P75]) of lycosin-Ⅰ against multidrug-resistant and non-multidrug-resistant Pseudomonas aeruginosa were 12 (8,32) μg/mL,and there was no statistical difference between them (U =42,P ＞0.05).About 50％ of multidrug resistant and non-multidrug resistant Pseudomonas aeruginosa could be killed by 4 × MIC of lycosin-Ⅰ during 60 minutes.When the concentration of lycosin-Ⅰ below MIC,such as 0,2 or 4 μg/mL,was co-cultured with multidrug resistant and non-multidrug resistant Pseudomonas aeruginosa for 24 hours,the growth of bacteria was fast during 6 and 16 hours,and then tended to be slow after 18 hours.When the concentration of lycosin-Ⅰ increased to 8 μg/mL,the bacteria were hard to grow.The in vitro antibacterial activity of lycosin-Ⅰ could be reduced by the addition of 5 mmol/L of Ca2+ or Mg2+,and the MICs of lycosin-Ⅰ against multidrug resistant and non-multidrug resistant Pseudomonas aeruginosa increased from 8 μg/mL to 64 μg/mL for 5 mmol/L of Ca2+,and from 8 μg/mL to 32 μg/mL for 5 mmol/L of Mg2+,respectively.But high concentrations of lycosin-Ⅰ (＞ 64 μg/mL or ＞ 32 μg/mL) could still maintain its antibacterial activity against multidrug resistant and non-multidrug resistant Pseudomonas aeruginosa.Conclusion Lyosin-Ⅰ can effectively inhibit the growth of Pseudomonas aeruginosa in vitro,and has certain salt tolerance,which may be developed into a new type of antibacterial drug.