The action of amphotericin B on Mycoplasma laidlawii

M. laidlawii grown in cholesterol-free medium are resistant to amphotericin B; when grown in the presence of cholesterol they are sensitive to the drug. Incubation of the resistant organisms in the presence of cholesterol results in a rapid conversion to sensitivity by a temperature-dependent process involving incorporation of sterol into the cells. Similarly, amphotericin B-sensitive M. laidlawii are rendered resistant by incubation in a cholesterol-free medium, and this change is associated with loss of some of the radioactivity previously incorporated from labeled cholesterol.