Cisneros Benavides M E
Universidad Autónoma Metropolitana-Xochimilco, México, D.F.
Rev Latinoam Microbiol. 1992 Jan-Mar;34(1):53-60.
By genetic studies, it was tried to find the mechanism by which a bacterial fraction from different isolated clinical cultures resistant to 25 micrograms/ml of kanamycin can grow in media containing 500 micrograms/ml of kanamycin (at a frequency of about 10(-5)). This study was done in six clinical isolates of Escherichia coli resistant to more than three antibiotics. The results from the bacterial fraction (subpopulation) resistant to high concentrations of kanamycin in the level of resistance to aminoglycoside and non-aminoglycoside antibiotics, in the conjugation experiments, and in the percentage of resistant bacteria to 500 micrograms/ml of kanamycin when the subpopulations were subsequently cultivated in the absence of antibiotics suggest that genetic amplification occurred when one of the strains was growing in the presence of 500 micrograms/ml of kanamycin. Moreover, this strain increased its frequency of survival in high kanamycin concentrations when it was transduced by bacteriophage P1, propagated in cultures resistant to 500 micrograms/ml of kanamycin.
通过遗传学研究，试图找出一种机制，即来自不同分离临床培养物的对25微克/毫升卡那霉素耐药的细菌组分，如何能够在含有500微克/毫升卡那霉素的培养基中生长（频率约为10^(-5)）。这项研究是在六株对三种以上抗生素耐药的大肠杆菌临床分离株中进行的。在对氨基糖苷类和非氨基糖苷类抗生素的耐药水平方面、在接合实验中以及在亚群随后在无抗生素条件下培养时对500微克/毫升卡那霉素的耐药细菌百分比方面，对高浓度卡那霉素耐药的细菌组分（亚群）的结果表明，当其中一个菌株在500微克/毫升卡那霉素存在的情况下生长时发生了基因扩增。此外，当该菌株被噬菌体P1转导并在对500微克/毫升卡那霉素耐药的培养物中繁殖时，它在高卡那霉素浓度下的存活频率增加。
