Reversal of the inhibitory action of chloramphenicol on the ribosomal peptidyl transfer reaction by erythromycin

Pleiotropic antibiotic resistance mutations associated with ribosomes and ribosomal subunits in Mycobacterium smegmatis

Viomycin-resistant strains isolated from Mycobacterium smegmatis demonstrated pleiotropic resistance to tuberactinomycin-N, capreomycin, streptomycin, and kanamycin as a result of mutational alteration of ribosomes, even though they were selected for resistance to a single antibiotic. The pleiotropic drug resistance of three mutants isolated by stepwise selection for resistance to viomycin was due to alteration of the 30S ribosomal subunit. One mutant, strain A, isolated independently by multiple-step selection to viomycin resistance, was resistant to viomycin, tuberactinomycin-N, and capreomycin through an alteration of the 50S ribosomal subunit, whereas it was sensitive to kanamycin but resistant to streptomycin through an alteration of the 30S ribosomal subunit. Three streptomycin-resistant strains, which were isolated by one-step selection at a high concentration of streptomycin, did not show significant co-resistance to any other antibiotics tested in culture and cell-free systems; streptomycin resistance in these mutants was localized on the 30S ribosomal subunit.

Growth inhibition and morphologic modulation of human fibroblastlike cells by erythromycin

In vitro exposures of mass cultures and clones of human diploid fibroblastlike cells to erythromycin, in concentrations of 50 to 400 micrograms/ml, results in increasing degrees of growth inhibition and augmented cell volume, with a shift toward larger proportions of cells of the epithelioid type and fewer of the fibroblast type. These alterations were reversed upon subculture in the absence of the antibiotic.

Properties of ribosomes from Streptomyces erythreus and Streptomyces griseus

Ribosomes from an erythromycin-producing strain, Streptomyces erythreus, lacked affinity for erythromycin and were also resistant to other macrolide antibiotics (leucomycin, spiramycin, and tylosin) and to lincomycin, whereas Streptomyces griseus B(3) ribosomes were susceptible to all of these antibiotics.