Greenwood D
J Gen Microbiol. 1975 Nov;91(1):110-8. doi: 10.1099/00221287-91-1-110.
The activities of polymyxin B sulphate, colistin (polymyxin E) sulphate and their sulphomethyl derivatives were compared by continuous turbidimetric monitoring of dense cultures of an Escherichia coli strain exposed to these agents. Judged by the concentration of antibiotic which caused a rapid fall in opacity of the culture, polymyxin B sulphate and colistin sulphate had similar activities, but the sulphomethyl compounds differed considerably: sulphomyxin sodium induced lysis of the culture at a concentration four times that of the parent compound, whereas colistin sulphomethate sodium induced a delayed fall in opacity consistent with recruitment of activity as the inactive sulphomethyl derivative was broken down to the parent compound. Durign overnight incubation, regrowth of cultures which had initially succumbed to polymyxin action occurred, apparently due to the selection of phenotypically resistant variants from within the population. In this way cultures could easily be adapted to growth in concentrations of antibiotic well above the conventionally-determined minimum inhibitory concentration. The comparative ease of adaptation was in the order: colistin sulphomethate greater than sulphomyxin greater than colistin sulphate greater than polymyxin B sulphate.
通过对暴露于这些药物的大肠杆菌菌株的密集培养物进行连续比浊监测，比较了硫酸多粘菌素B、硫酸粘菌素（多粘菌素E）及其磺甲基衍生物的活性。以导致培养物浊度迅速下降的抗生素浓度来判断，硫酸多粘菌素B和硫酸粘菌素具有相似的活性，但磺甲基化合物有很大差异：磺粘菌素钠在浓度为母体化合物四倍时诱导培养物裂解，而甲磺粘菌素钠诱导浊度延迟下降，这与随着无活性的磺甲基衍生物分解为母体化合物而活性增加一致。在过夜培养期间，最初因多粘菌素作用而死亡的培养物出现了再生长，显然是由于从群体中选择了表型抗性变体。通过这种方式，培养物可以很容易地适应在远高于传统测定的最低抑菌浓度的抗生素浓度下生长。适应的相对难易程度顺序为：甲磺粘菌素＞磺粘菌素＞硫酸粘菌素＞硫酸多粘菌素B。
