title: Molecular epidemiology of pneumococcal isolates from children in China.
abstract: OBJECTIVE
  To investigate the molecular epidemiology of pneumococcal isolates in Chongqing, China.
  
  
  METHODS
  In this cross-sectional study, 51 invasive Streptococcus pneumoniae (S. pneumoniae) strains were from children with invasive pneumococcal disease (IPD) and 32 carriage strains from healthy children from January 2010 to December 2013 at the Children's Hospital of Chongqing Medical University, Chongqing, China. Multilocus sequence typing was used to identify the sequence types (STs). Capsular serotypes were determined by multiplex polymerase chain reaction. Drug susceptibility and resistance was determined by minimum inhibitory concentrations.
  
  
  RESULTS
  In this study, 11 serotypes were identified among the 83 S. pneumoniae clinical isolates tested. Prevalent serotypes were 19A (20.4%), 6A/B (20.4%), 19F (15.7%), 14 (14.5%), and 23F (10.8%). Serotype 19F was the most frequent carriage strain, and serotype 19A was the most frequent invasive strain. The ST983 was the most prevalent ST for carriage strains, and ST320 was the most prevalent ST for invasive strains. For gene analysis, psaA (99.5%) and piaA (98.6%) were present and much conserved in all pneumococci tested. The cps2A and pcsB genes were more frequent in invasive isolates than carriage strains. Antimicrobial resistance rates of invasive pneumococcal isolates to erythromycin, penicillin, meropenem, cefotaxime, and clindamycin were higher than the carriage isolates from children.
  
  
  CONCLUSIONS
  Our epidemiological evidence shows that 19A, 6A/B, 19F, 14, and 23F remain the most prevalent serotypes, which can be targeted by PCV13. Genotypes and drug resistance varied between carriage and invasive strains. The PsaA and PiaA may be good protein vaccine candidates.
authors.affiliation: Key Laboratory of Diagnostic Medicine designated by the Ministry of Education, College of Laboratory Medicine, Chongqing Medical University, Chongqing, China. E-mail. 82864898@qq.com.
authors.forename: Li-Hua
authors.initials: LH
authors.lastname: Kang
authors.forename: Meng-Juan
authors.initials: MJ
authors.lastname: Liu
authors.forename: Wen-Chun
authors.initials: WC
authors.lastname: Xu
authors.forename: Jing-Jing
authors.initials: JJ
authors.lastname: Cui
authors.forename: Xue-Mei
authors.initials: XM
authors.lastname: Zhang
authors.forename: Kai-Feng
authors.initials: KF
authors.lastname: Wu
authors.forename: Qun
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002353:Carrier State / Q000453:epidemiology*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008826:Microbial Sensitivity Tests; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D014774:Virulence / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents