Inactivation of mycoplasmas by long-chain alcohols

In this report, we describe the inhibitory activity of long-chain alcohols on the growth of Mycoplasma gallisepticum and Mycoplasma pneumoniae. Peak inhibition was recorded with saturated primary alcohols (64 microM) varying in chain length from 16 to 19 carbon atoms. The unsaturated alcohols (oleyl, linoleyl, and linolenyl) and the secondary alcohol (pentadecan-2-ol), when employed in the same test conditions, were considerably less effective growth inhibitors than the primary saturated alcohols. Stearic and palmitic acids were also ineffective as growth inhibitors of M. pneumoniae and M. gallisepticum at a 128 microM concentration. Because these antimycoplasma agents are fatty alcohols and cholesterol is known to be required for the growth of some mycoplasmas, additional cholesterol was added in an attempt to reverse the inhibition observed with these agents. Cholesterol at a 128 microM concentration did not significantly relieve the growth inhibition observed with stearyl alcohol at a 48 microM concentration. Mammalian cell cultures were found to be significantly more resistant to the effects of these inhibitory alcohols than were the mycoplasmas. Electron micrographs showed that inclusion of stearyl alcohol in the culture medium produced changes in the cellular morphology of the treated mycoplasmas.