title: Diversity of ribosomal mutations conferring resistance to macrolides, clindamycin, streptogramin, and telithromycin in Streptococcus pneumoniae.
abstract: Mechanisms of resistance were studied in 22 macrolide-resistant mutants selected in vitro from 5 parental strains of macrolide-susceptible Streptococcus pneumoniae by serial passage in various macrolides (T. A. Davies, B. E. Dewasse, M. R. Jacobs, and P. C. Appelbaum, Antimicrob. Agents Chemother., 44:414-417, 2000). Portions of genes encoding ribosomal proteins L22 and L4 and 23S rRNA (domains II and V) were amplified by PCR and analyzed by single-strand conformational polymorphism analysis to screen for mutations. The DNA sequences of amplicons from mutants that differed from those of parental strains by their electrophoretic migration profiles were determined. In six mutants, point mutations were detected in the L22 gene (G95D, P99Q, A93E, P91S, and G83E). The only mutant selected by telithromycin (for which the MIC increased from 0.008 to 0.25 microg/ml) contained a combination of three mutations in the L22 gene (A93E, P91S, and G83E). L22 mutations were combined with an L4 mutation (G71R) in one strain and with a 23S rRNA mutation (C2611A) in another strain. Nine other strains selected by various macrolides had A2058G (n = 1), A2058U (n = 2), A2059G (n = 1), C2610U (n = 1), and C2611U (n = 4) mutations (Escherichia coli numbering) in domain V of 23S rRNA. One mutant selected by clarithromycin and resistant to all macrolides tested (MIC, >32 microg/ml) and telithromycin (MIC, 4 microg/ml) had a single base deletion (A752) in domain II. In six remaining mutants, no mutations in L22, L4, or 23S rRNA could be detected.
authors.affiliation: UFR des Sciences Pharmaceutiques, Caen, France.
authors.forename: Annie
authors.initials: A
authors.lastname: Canu
authors.forename: Brigitte
authors.initials: B
authors.lastname: Malbruny
authors.forename: Maëlle
authors.initials: M
authors.lastname: Coquemont
authors.forename: Todd A
authors.initials: TA
authors.lastname: Davies
authors.forename: Peter C
authors.initials: PC
authors.lastname: Appelbaum
authors.forename: Roland
authors.initials: R
authors.lastname: Leclercq
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002981:Clindamycin / Q000494:pharmacology; D004351:Drug Resistance / Q000235:genetics*; D029968:Escherichia coli Proteins; D005820:Genetic Testing; D014644:Genetic Variation; D006801:Humans; D048628:Ketolides; D018942:Macrolides; D008969:Molecular Sequence Data; D009154:Mutation; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics; D012269:Ribosomal Proteins / Q000235:genetics; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000235:genetics*; D025361:Streptogramins / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D048628:Ketolides; D018942:Macrolides; D012338:RNA, Ribosomal, 23S; D016601:RNA-Binding Proteins; D012269:Ribosomal Proteins; D025361:Streptogramins; C056368:ribosomal protein L4; C489371:rplV protein, E coli; C067169:RPL22 protein, human; D002981:Clindamycin; C106791:telithromycin