Charactertization of spontaneous fosfomycin (phosphonomycin)-resistant cells of Escherichia coli B in vitro.

The characteristics of spontaneous fosfomycin-resistant cells isolated in vitro were investigated. Distribution of resistance level to the drug in Escherichia coli B was thought to be broad and, for this reason, resistance to the drug seemed to develope easily in vitro. In the process of isolating the resistant cells, two groups of cells, differing in colony size, were distinguished. Smaller colony-forming cells appeared more frequently than Larger colony-forming ones. Many of the former seemed to be slow growers and decreased simultaneously in utilization of several carbohydrates. One of the Smaller colony-forming isolates was distinctly different from glp T- or uhp-.