title: Dynamics of serotype 14 Streptococcus pneumoniae population causing acute respiratory infections among children in China (1997-2012).
abstract: BACKGROUND
  In the last decade, the Streptococcus pneumoniae population has changed, mainly due to the abuse of antibiotics. The aim of this study was to determine the genetic structure of 144 S. pneumonia serotype 14 isolates collected from children with acute respiratory infections during 1997-2012 in China.
  
  
  METHODS
  All isolated pneumococci were tested for their sensitivity to 11 kinds of antibiotics with the E-test method or disc diffusion. The macrolides resistance genes ermB and mefA, as well as the sulfamethoxazole-trimethoprim resistance gene dihydrofolate reductase (DHFR) were detected by polymerase chain reaction (PCR). The sequence types (STs) were analyzed with multilocus sequence typing (MLST).
  
  
  RESULTS
  From 1997 to 2012, the percentage of serotype 14 S. pneumonia isolates in the whole isolates increased. All of the 144 serotype 14 S. pneumonia isolates were susceptible to amoxicillin-clavulanic acid, vancomycin and levofloxacin. No penicillin resistant isolate was found, and the intermediate rate was as low as 0.7 %. Erythromycin resistance was confirmed among 143 isolates. The ermB gene was determined in all erythromycin resistant isolates, and the mefA gene was positive additionally in 13 of them. The non-susceptibility rate to the tested cephalosporins increased from 1997-2012. All trimethoprim-resistant isolates contained the Ile100-Leu mutation. Overall, 30 STs were identified, among which ST876 was the most prevalent, followed by ST875. During the study period, the percentage of CC876 increased from 0 % in 1997-2000 to 96.4 % in 2010-2012, whereas CC875 decreased from 84.2 to 0 %. CC876 showed higher non-susceptibility rates to β-lactam antibiotics than CC875.
  
  
  CONCLUSIONS
  The percentage of serotype 14 S. pneumonia isolates increased over time in China. The increase of resistance to β-lactam antibiotics in this serotype isolates was associated with the spread of CC876.
authors.affiliation: Key Laboratory of Major Diseases in Children and National Key Discipline of Pediatrics, Ministry of Education, Beijing Pediatric Research Institute, Beijing Children's Hospital Affiliated to Capital Medical University, Beijing, P. R. China. ming1219ming@163.com.
authors.forename: Mingming
authors.initials: M
authors.lastname: He
authors.affiliation: Key Laboratory of Major Diseases in Children and National Key Discipline of Pediatrics, Ministry of Education, Beijing Pediatric Research Institute, Beijing Children's Hospital Affiliated to Capital Medical University, Beijing, P. R. China. jiuhu2655@sina.com.
authors.forename: Kaihu
authors.initials: K
authors.lastname: Yao
authors.affiliation: Key Laboratory of Major Diseases in Children and National Key Discipline of Pediatrics, Ministry of Education, Beijing Pediatric Research Institute, Beijing Children's Hospital Affiliated to Capital Medical University, Beijing, P. R. China. shiwei613115@126.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Shi
authors.affiliation: Key Laboratory of Major Diseases in Children and National Key Discipline of Pediatrics, Ministry of Education, Beijing Pediatric Research Institute, Beijing Children's Hospital Affiliated to Capital Medical University, Beijing, P. R. China. weigaococo@yahoo.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Gao
authors.affiliation: Key Laboratory of Major Diseases in Children and National Key Discipline of Pediatrics, Ministry of Education, Beijing Pediatric Research Institute, Beijing Children's Hospital Affiliated to Capital Medical University, Beijing, P. R. China. yuanyuan808yuan@sina.com.
authors.forename: Lin
authors.initials: L
authors.lastname: Yuan
authors.affiliation: Key Laboratory of Major Diseases in Children and National Key Discipline of Pediatrics, Ministry of Education, Beijing Pediatric Research Institute, Beijing Children's Hospital Affiliated to Capital Medical University, Beijing, P. R. China. yusangjie@hotmail.com.
authors.forename: Sangjie
authors.initials: S
authors.lastname: Yu
authors.affiliation: Key Laboratory of Major Diseases in Children and National Key Discipline of Pediatrics, Ministry of Education, Beijing Pediatric Research Institute, Beijing Children's Hospital Affiliated to Capital Medical University, Beijing, P. R. China. shiwei613115@126.com.
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Yang
mesh_terms: D019980:Amoxicillin-Potassium Clavulanate Combination / Q000627:therapeutic use; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D024881:Drug Resistance, Bacterial; D004917:Erythromycin / Q000627:therapeutic use; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D058885:Multilocus Sequence Typing; D011008:Pneumococcal Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control; D016133:Polymerase Chain Reaction; D012141:Respiratory Tract Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control; D065288:Serogroup; D013296:Streptococcus pneumoniae / Q000145:classification / Q000302:isolation & purification*
chemical_list: D000900:Anti-Bacterial Agents; D004917:Erythromycin; D019980:Amoxicillin-Potassium Clavulanate Combination