title: Synergistic effects of a macrolide and a cell wall-affecting antibiotic on Pseudomonas aeruginosa in vitro and in vivo. 3. Incorporation of [14C]midecamycin acetate (MOM) into P. aeruginosa pretreated with cell wall-affecting antibiotics.
abstract: The occurrence in beta-lactam treated patients of unstable L-forms of Pseudomonas aeruginosa insensitive to various antibiotics and synergistic effect of combined action of cell wall-affecting antibiotics and macrolide on Pseudomonas infection led us to examine the effects of macrolide on P. aeruginosa pretreated with cell wall-affecting antibiotics. The effects of macrolide antibiotics such as midecamycin acetate (MOM) on P. aeruginosa was investigated, a rapid killing effect by MOM was noted after treatment with suboptimal doses of cell wall-affecting antibiotics such as polymyxin B, carbenicillin, dibekacin or fosfomycin. Incorporation of [14C]MOM into intact P. aeruginosa cells was not significant, but was apparent into L-form cells or cells pretreated with cell wall-affecting antibiotics. The incorporated radioactivity was found in the 70 S ribosome fraction, binding with the 50 S subunits of ribosome in both cases. These results indicate that under certain conditions a macrolide antibiotic can enter the P. aeruginosa cell.
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D002250:Carbon Radioisotopes; D002473:Cell Wall / Q000187:drug effects*; D004357:Drug Synergism; D007740:L Forms / Q000187:drug effects; D007933:Leucomycins / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D002250:Carbon Radioisotopes; D007933:Leucomycins; C026483:midecamycin