title: Loss of plasmid-mediated resistance after conversion of a group B streptococcus strain to a stable cell wall deficient variant.
abstract: A group B streptococcus strain carrying plasmid DNA determining resistance to several drugs was converted by penicillin to cell wall (CW) defective and then to CW deficient variants (L-forms). The stable CW deficient variants became susceptible to antibiotics in study. Dye-buoyant density analysis of the DNA of CW deficient variants showed that the loss of antibiotic resistance was associated with the loss of extrachromosomal DNA.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002473:Cell Wall / Q000032:analysis / Q000382:microbiology; D004269:DNA, Bacterial / Q000032:analysis; D003864:Depression, Chemical; D010403:Penicillin Resistance; D010406:Penicillins / Q000494:pharmacology; D010957:Plasmids / Q000187:drug effects*; D013292:Streptococcus agalactiae / Q000166:cytology / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D010406:Penicillins