title: Emergence of group A streptococcus strains with different mechanisms of macrolide resistance.
abstract: The mechanisms of resistance to macrolides in seven group A streptococcal (Streptococcus pyogenes) isolates that were the cause of pharyngitis in children who were unsuccessfully treated with azithromycin (10 mg/kg of body weight/day for 3 days) were evaluated. All posttreatment strains were found to be genetically related to the pretreatment isolates by random amplified polymorphism DNA analysis and pulsed-field gel electrophoresis. Two isolates had acquired either a mef(A) or an erm(B) gene, responsible for macrolide efflux and ribosomal modification, respectively. Three isolates displayed mutations in the gene encoding the L4 ribosomal protein that is part of the exit tunnel within the 50S subunit of the bacterial ribosome. In the two remaining posttreatment strains, the mechanisms of macrolide resistance could not be elucidated.
authors.affiliation: Service de Microbiologie, Hôpital Robert Debré, Paris, France. edouard.bingen@rdb.ap-hop-paris.fr
authors.forename: Edouard
authors.initials: E
authors.lastname: Bingen
authors.forename: Roland
authors.initials: R
authors.lastname: Leclercq
authors.forename: Frédéric
authors.initials: F
authors.lastname: Fitoussi
authors.forename: Naïma
authors.initials: N
authors.lastname: Brahimi
authors.forename: Brigitte
authors.initials: B
authors.lastname: Malbruny
authors.forename: Dominique
authors.initials: D
authors.lastname: Deforche
authors.forename: Robert
authors.initials: R
authors.lastname: Cohen
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D004269:DNA, Bacterial / Q000032:analysis; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D018942:Macrolides; D008826:Microbial Sensitivity Tests; D010612:Pharyngitis / Q000382:microbiology*; D019105:Random Amplified Polymorphic DNA Technique; D012269:Ribosomal Proteins / Q000235:genetics; D013290:Streptococcal Infections / Q000382:microbiology*; D013297:Streptococcus pyogenes / Q000187:drug effects* / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D018942:Macrolides; D012269:Ribosomal Proteins; C056368:ribosomal protein L4