Aubert G, Carricajo A, Fonsale N, Vautrin A-C
Laboratoire d'Antibiologie, Hôpital Nord, CHU de Saint-Etienne, 42055 Saint-Etienne Cedex 02, France.
Pathol Biol (Paris). 2009 May;57(3):236-9. doi: 10.1016/j.patbio.2007.12.005. Epub 2008 Mar 6.
To compare mutant prevention concentration (MPC) of ciprofloxacin and time-killing curve with regards to 11 genotyped Escherichia coli.
MICs were determined using the E-test method. Time-killing studies were performed in accordance with the NCCLS guidelines. The genes gyrA, gyrB, parC, parE and marR were amplified by PCR and sequenced. The MPC was defined as the lowest antibiotic concentration preventing the growth of resistant colonies when 10(10) CFU/mL were spread on a solid medium.
Strains with no genes gyrA, gyrB, parC, parE and marR mutation presented MIC less or equal to 0.023 mg/L and MPC less or equal to 0.25 mg/L. Strains with two mutations (gyrA and parC) presented MIC equal to 1.5 mg/L and MPC equal to 4 mg/L. Strains with one mutation (gyrA) presented MIC less or equal to 0.75 mg/L, but MPC ranged from 0.5 to 6 mg/L depending of the MIC of ciprofloxacin. The time-killing curves for ciprofloxacin showed a bactericidal activity of 0.25 mg/L in 1h for strains without mutation, compared with a bactericidal activity of 2 and 4 mg/L in 4h for strains with one and two mutations, respectively.
For strains of E. coli resistant to nalidixic acid, it was necessary to evaluate the MIC of ciprofloxacin in order to asses the optimal dosage of ciprofloxacin.
比较环丙沙星对11株基因分型的大肠杆菌的突变预防浓度（MPC）和时间杀菌曲线。
采用E-test法测定最低抑菌浓度（MIC）。按照美国国家临床实验室标准委员会（NCCLS）指南进行时间杀菌研究。通过聚合酶链反应（PCR）扩增并测序gyrA、gyrB、parC、parE和marR基因。MPC定义为当10(10)CFU/mL接种于固体培养基上时，阻止耐药菌落生长的最低抗生素浓度。
未发生gyrA、gyrB、parC、parE和marR基因突变的菌株MIC小于或等于0.023mg/L，MPC小于或等于0.25mg/L。发生两种突变（gyrA和parC）的菌株MIC等于1.5mg/L，MPC等于4mg/L。发生一种突变（gyrA）的菌株MIC小于或等于0.75mg/L，但MPC根据环丙沙星的MIC范围为0.5至6mg/L。环丙沙星的时间杀菌曲线显示，未发生突变的菌株在1小时内0.25mg/L具有杀菌活性，而发生一种和两种突变的菌株分别在4小时内2mg/L和4mg/L具有杀菌活性。
对于耐萘啶酸的大肠杆菌菌株，有必要评估环丙沙星的MIC以确定环丙沙星的最佳剂量。
