title: [Macrolide-resistant Streptococcus pneumoniae in the pediatric population in Beijing].
abstract: OBJECTIVE
  To analyze the mechanisms of macrolide resistance in Streptococcus pneumoniae from children in Beijing.
  
  
  METHODS
  The MICs of penicillin and erythromycin were determined by the E-test methods for 200 Streptococcus pneumoniae isolates collected from 2002 to 2003 at Beijing Children's Hospital. MICs of azithrhomycin, clarithromycin, acetylspiramycin and clindamycin for 147 erythromycin-resistant isolates were detected by the agar dilution methods. For phenotyping, macrolide resistance induction tests were used in erythromycin-resistant isolates. PCR was used to determine the presence of the erythromycin-resistant genes.
  
  
  RESULTS
  Of 200 Streptococcus pneumoniae isolates, 89.5% were resistant to erythromycin. In 147 erythromycin-resistant isolates, resistance rates were as follows: azithromycin, 100%; clarithromycin, 100%; acetylspiramycin, 95.2%; and clindamycin, 95.9%. The most common macrolide resistance phenotype was the cMIS phenotype (95.9%), 1.4% had the iMLS phenotype and 2.7% the M phenotype. Erythromycin-resistant isolates were characterized for the underlying resistance genotype, with 79.6% having the ermB genotypes, 17.7% having both ermB and mefA, 2.7% having the mefA, and none having neither ermB nor mefA genotypes.
  
  
  CONCLUSIONS
  The rates of carriage of macrolide-resistant Streptococcus pneumoniae by children were high in Beijing during 2002 - 2003. cMLS was the most prevalent phenotype among erythromycin-resistant Streptococcus pneumoniae isolates, and ribosomal modification (ermB gene coded) was the main resistance mechanism against macrolides in Beijing region.
authors.affiliation: Laboratory of Microbiology and Immunology, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital University of Medical Sciences, Beijing 100045, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Yang
authors.forename: Xu-zhuang
authors.initials: XZ
authors.lastname: Shen
authors.forename: Yong-hong
authors.initials: YH
authors.lastname: Wang
authors.forename: Lin
authors.initials: L
authors.lastname: Yuan
authors.forename: Sang-jie
authors.initials: SJ
authors.lastname: Yu
authors.forename: Yong-hong
authors.initials: YH
authors.lastname: Yang
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002648:Child; D002681:China; D017291:Clarithromycin / Q000494:pharmacology; D002981:Clindamycin / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004917:Erythromycin / Q000494:pharmacology; D005838:Genotype; D006801:Humans; D018942:Macrolides / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D010406:Penicillins / Q000494:pharmacology; D010641:Phenotype; D015572:Spiramycin / Q000031:analogs & derivatives / Q000494:pharmacology; D013290:Streptococcal Infections / Q000235:genetics / Q000382:microbiology*; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D018942:Macrolides; D010406:Penicillins; C033163:acetylspiramycin; D002981:Clindamycin; D004917:Erythromycin; D015572:Spiramycin; D017291:Clarithromycin