title: Characterization of erythromycin-resistant Streptococcus pneumoniae isolates causing invasive diseases in Chinese children.
abstract: BACKGROUND
  Erythromycin-resistant Streptococcus pneumoniae isolates that causing invasive pneumococcal diseases (IPD) in Chinese children remain uncharacterized. This study aims to identify the resistance genes associated with erythromycin resistance and to determine the genetic relationships of IPD isolates in Chinese children.
  
  
  METHODS
  A total of 171 S. pneumoniae strains were isolated from 11 medical centers in China from 2006 to 2008. All the isolates were characterized via serotyping and antibiotic susceptibility determination. The erythromycin-resistant isolates were further characterized via ermB and mefA gene detection, multi-locus sequence typing analysis, and pulsed-field gel electrophoresis.
  
  
  RESULTS
  A total of 164 (95.9%) isolates showed resistance to erythromycin, of which 162 strains with high high-level resistance (MIC ≥ 256 µg/ml). A total of 104 (63.4%) isolates carry the ermB gene alone, whereas 59 (36.0%) harbor both ermB and mefA genes. Of the 59 strains, 54 were of serotypes 19A and 19F and were identified as highly clonal and related to the Taiwan(19F)-14 clone.
  
  
  CONCLUSIONS
  The erythromycin resistance rate in IPD isolates is significantly high and is predominantly mediated by the ermB gene. Isolates that carry both ermB and mefA genes are predominantly of serotypes 19A and 19F.
authors.affiliation: Key Laboratory of Major Diseases in Children and the National Key Discipline of Pediatrics (Capital Medical University), Ministry of Education, Beijing Pediatrics Research Institute, Beijing Children's Hospital, Beijing 10045, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Ma
authors.forename: Kai-hu
authors.initials: KH
authors.lastname: Yao
authors.forename: Gui-lin
authors.initials: GL
authors.lastname: Xie
authors.forename: Yue-jie
authors.initials: YJ
authors.lastname: Zheng
authors.forename: Chuan-qing
authors.initials: CQ
authors.lastname: Wang
authors.forename: Yun-xiao
authors.initials: YX
authors.lastname: Shang
authors.forename: Hui-yun
authors.initials: HY
authors.lastname: Wang
authors.forename: Li-ya
authors.initials: LY
authors.lastname: Wan
authors.forename: Lan
authors.initials: L
authors.lastname: Liu
authors.forename: Chang-chong
authors.initials: CC
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Ji
authors.forename: Xi-wei
authors.initials: XW
authors.lastname: Xu
authors.forename: Ya-ting
authors.initials: YT
authors.lastname: Wang
authors.forename: Pei-ru
authors.initials: PR
authors.lastname: Xu
authors.forename: Sang-jie
authors.initials: SJ
authors.lastname: Yu
authors.forename: Yong-hong
authors.initials: YH
authors.lastname: Yang
mesh_terms: D000293:Adolescent; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D004917:Erythromycin / Q000494:pharmacology*; D006801:Humans; D007223:Infant; D058885:Multilocus Sequence Typing; D011008:Pneumococcal Infections / Q000382:microbiology*; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D004917:Erythromycin