title: Mechanism of resistance to antibiotic synergism in enterococci.
abstract: Enterococci exhibit two types of resistance to streptomycin. Moderately high-level resistance is observed in most naturally occurring strains and can be overcome by simultaneous exposure to penicillin. In addition, very high-level resistance is found in those strains against which penicillin plus streptomycin fail to produce synergism in vitro. To study the mechanism of streptomycin resistance in enterococci, ribosomes from a wild-type strain and from a highly streptomycin-resistant mutant were isolated, characterized, and studied in an in vitro amino acid incorporation system. The ribosomes from the organism with moderately high-level streptomycin resistance were sensitive to streptomycin in vitro, suggesting that this type of resistance is caused by failure of streptomycin to reach the ribosomes. Very high-level resistance (and lack of penicillin-streptomycin synergism), on the other hand, appears to be due to ribosomally mediated streptomycin resistance.
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D002247:Carbon Isotopes; D002499:Centrifugation, Density Gradient; D003956:Dialysis; D004357:Drug Synergism; D013293:Enterococcus faecalis / Q000187:drug effects*; D005827:Genetics, Microbial; D008274:Magnesium; D009705:Nucleosides; D010403:Penicillin Resistance; D010406:Penicillins / Q000494:pharmacology*; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism; D013307:Streptomycin / Q000494:pharmacology*; D013395:Sucrose
chemical_list: D000596:Amino Acids; D002247:Carbon Isotopes; D009705:Nucleosides; D010406:Penicillins; D013395:Sucrose; D008274:Magnesium; D013307:Streptomycin