INHIBITION OF THE PLEUROPNEUMONIA-LIKE ORGANISM MYCOPLASMA GALLISEPTICUM BY CERTAIN POLYENE ANTIFUNGAL ANTIBIOTICS

Lampen, J. Oliver (Rutgers, The State University, New Brunswick, N.J.),James W. Gill, Peter M. Arnow, and I. Magana-Plaza . Inhibition of the pleuropneumonia-like organismMycoplasma gallisepticum by certain polyene antifungal antibiotics. J. Bacteriol.86: 945–949. 1963.—The growth ofMycoplasma gallisepticum , a sterol-requiring pleuropneumonia-like organism (PPLO), was inhibited by certain polyene antifungal antibiotics at the following concentrations: filipin, 0.5 μg/ml; amphotericin B, 3 μg/ml; and fungichromin, 10 μg/ml. The inhibition of the organism was due to fungicidal action of the polyenes rather than to decreased availability of the sterol. The PPLO rapidly bound nystatin (NY), but was relatively insensitive to this antifungal agent or toN -acetyl-candidin (NAC). Even with a comparatively small inoculum, 100 μg of NY per ml or 50 μg of NAC per ml, were required to inhibit growth. In contrast,Saccharomyces cerevisiae , growing under similar conditions, was completely inhibited by 3 μg of NY or NAC per ml. Filipin, however, was effective against both organisms, inhibiting PPLO and yeast at 0.5 μg/ml and 3 μg/ml, respectively. The relative insensitivity of PPLO to NY was not the result of protection by the sterol present in the growth medium. These organisms, incubated for 2 hr in sterol-free buffer in the presence of 20 μg of NY per ml showed little, if any, inhibition of growth when transferred to growth medium. Under the same conditions, more than 99% of a yeast suspension was killed. It is suggested that the PPLO are primarily sensitive to the disruptive action on the cell membrane which is characteristic of the smaller polyenes (34 to 37 carbon atoms).