title: Separation of erythromycin-resistant and -susceptible subpopulations of Escherichia coli 15 by partition in two-polymer aqueous phases.
abstract: Partition of cells in two-polymer aqueous phases depends on subtle differences in the cells' surface properties (primarily surface charge). A culture of Escherichia coli 15 arg(-) was subjected to countercurrent distribution in a dextranpolyethylene glycol aqueous phase system and found to consist of two well-differentiated subpopulations. Clones derived from these two subpopulations (designated clones 5 and 6) exhibited characteristic partitions and were stable on subculture. Clone 5 cells were found to be susceptible to erythromycin and clone 6 cells were resistant. When a culture of clone 5 was exposed to erythromycin, resistant mutants were selected with the same partition as clone 6. Countercurrent distribution in two-polymer aqueous phase systems is thus shown to be a sensitive method for detecting some heterogeneities of bacterial populations and resolving such mixtures. Possible clinical implications of changes in bacterial surface properties associated with acquired drug resistance are discussed.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D003911:Dextrans; D004352:Drug Resistance, Microbial; D004917:Erythromycin / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D011092:Polyethylene Glycols; D013499:Surface Properties
chemical_list: D003911:Dextrans; D011092:Polyethylene Glycols; D004917:Erythromycin