Liu Yu-Qing, Zhang Yu-Zhong, Sun Cai-Yun, Gao Pei-Ji
Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Science, Jinan 250100, China.
Am J Chin Med. 2005;33(4):671-82. doi: 10.1142/S0192415X05003260.
The antibacterial pharmacodynamics against E. coli of Chinese medicine (CM) Rhizoma coptidis (Coptis Root) and its formula Sanhuang, and the control antibiotics enoxacin, were analyzed by a concentration-killing curve (CKC) approach, and the novel parameters BC50 and r for antibacterial potency were proposed. Using the agar plate method, about 400 cells of E. coli were evenly inoculated into LB agar plates containing a series of different concentrations of CM or antibiotic, and after a 24 hour incubation at 37 degrees C, all the viable colonies were enumerated. This resulted in a sigmoid concentration-killing curve , in which No, that could be closely fitted (R2 > 0.9) with the function: N = 1 + e(r(x-BC50))/N0 in which N0, BC50 and r represent meaningfully inoculums size, median bactericidal concentration, and bactericidal intensity, respectively. N modeled the survival of colony-forming units on each plate (CFU/plate) in a concentration series x of the drug. The CKC was symmetrical about its single inflexion (BC50, N0/2). Therefore theoretically, 2BC50 can replace MBC (minimum bactericidal concentration). BC1 = BC50 + r/ln(N0-1), the drug concentration at r which only one colony survived, was the least critical value of MBC in CKC. The parameters 2BC50 and BC1 agreed more closely with the definition of MBC, and were little affected by either the biochemical basis of the antibacterial or the inoculum's size (200-400 CFU/plate), and were determined by a multi-point curve. As a result, these were more accurate, reproducible and practical as metrics than was the endpoint of MBC. The two-dimensional CKC, involving BC50 and r, captures the intrinsic dynamics of the antibacterial effect of CM/strain versus concentration, and it is consistent with the Logistic equation of the bacterial growth curve in the format. This verified approach has considerable value as a tool for the accurate and proper administration of CM. The CKC of CM, different from that of antibiotics, is likely to be the resultant force of each ingredient in certain CM, which provides a clue to solve the problem of antibiotic resistance.
采用浓度-杀菌曲线（CKC）法分析了中药黄连及其方剂三黄对大肠杆菌的抗菌药效动力学，并提出了新的抗菌效力参数BC50和r。采用琼脂平板法，将约400个大肠杆菌细胞均匀接种到含有一系列不同浓度黄连或抗生素的LB琼脂平板上，于37℃孵育24小时后，计数所有活菌菌落。由此得到一条S形浓度-杀菌曲线，其中No可与函数N = 1 + e(r(x - BC50))/N0紧密拟合（R2 > 0.9），式中N0、BC50和r分别有意义地代表接种量、半数杀菌浓度和杀菌强度。N模拟了药物浓度系列x中每个平板上菌落形成单位（CFU/平板）的存活情况。CKC关于其单一拐点（BC50，N0/2）对称。因此从理论上讲，2BC50可替代最低杀菌浓度（MBC）。BC1 = BC50 + r/ln(N0 - 1)，即仅一个菌落存活时的药物浓度r，是CKC中MBC的最低临界值。参数2BC50和BC1与MBC的定义更相符，且受抗菌生化基础或接种量大小（200 - 400 CFU/平板）的影响较小，由多点曲线确定。因此，作为指标，它们比MBC终点更准确、可重复且实用。涉及BC50和r的二维CKC捕捉了黄连/菌株抗菌作用相对于浓度的内在动力学，且与细菌生长曲线的逻辑斯蒂方程形式一致。这种经过验证的方法作为一种准确合理应用黄连的工具具有相当大的价值。黄连的CKC与抗生素的不同，可能是某些黄连中各成分的合力，这为解决抗生素耐药性问题提供了线索。
