title: Novel mechanism of macrolide resistance in Streptococcus pneumoniae.
abstract: The mechanism of macrolide resistance was examined in 73 clinical isolates of Streptococcus pneumoniae. Two distinct resistance phenotypes were observed: high-level macrolides-lincosamides-streptogramin B (MLS) resistance and low-level macrolide resistance with lincosamide susceptibility. High-level MLS resistance was associated with the presence of ermAM. Strains with the low-level resistant phenotype (novel) were negative for ermA, ermC, ermAM, ereA, ereB and msrA by polymerase chain reaction (PCR) amplification with gene-specific primers. Ribosomes isolated from novel strains bound the same amount of [14C]-erythromycin as ribosomes from sensitive strains. These novel strains also did not inactivate the macrolide. The novel mechanism was found in 41% of the erythromycin resistant S. pneumoniae examined.
authors.affiliation: Abbott Laboratories, Abbot Park, Illinois, USA.
authors.forename: V D
authors.initials: VD
authors.lastname: Shortridge
authors.forename: R K
authors.initials: RK
authors.lastname: Flamm
authors.forename: N
authors.initials: N
authors.lastname: Ramer
authors.forename: J
authors.initials: J
authors.lastname: Beyer
authors.forename: S K
authors.initials: SK
authors.lastname: Tanaka
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins; D001681:Biological Assay; D002265:Carboxylic Ester Hydrolases / Q000235:genetics; D002981:Clindamycin / Q000494:pharmacology; D017931:DNA Primers; D004352:Drug Resistance, Microbial / Q000235:genetics*; D004917:Erythromycin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D005798:Genes, Bacterial; D026901:Membrane Transport Proteins; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism; D013296:Streptococcus pneumoniae / Q000187:drug effects*; D012359:tRNA Methyltransferases / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D017931:DNA Primers; D026901:Membrane Transport Proteins; C066202:msrA protein, Staphylococcus epidermidis; D002981:Clindamycin; D004917:Erythromycin; D012359:tRNA Methyltransferases; D002265:Carboxylic Ester Hydrolases; C046388:erythromycin esterase