title: [Multilocus sequence typing and pulsed-field gel electrophoresis analysis of Salmonella Paratyphi A isolates from 2000 to 2008, China].
abstract: OBJECTIVE
  To analyze molecular and evolution characteristics of Salmonella Paratyphi A isolates from 2000 to 2008, China.
  
  
  METHODS
  Using pulsed-field gel electrophoresis (PFGE) method with SpeI restriction enzyme, and multilocus sequence typing (MLST) method based on housekeeping genes (aroC, thrA, hisD, purE, sucA, dnaN, hemD, adk, and purA), the genomic variations of 118 Salmonella Paratyphi A isolates from 10 regions during 2000 to 2008 were analyzed.
  
  
  RESULTS
  Using PFGE method, 118 Salmonella Paratyphi A isolates were clustered into 32 PFGE patterns, and 5 patterns were predominant (5 isolates or above). However, only 2 MLST types were identified for all isolates with MLST method. Among all Salmonella Paratyphi A isolates, the sequences of housekeeping genes were highly conservative and showed a high degree of cloning.
  
  
  CONCLUSIONS
  For Chinese epidemic Salmonella Paratyphi A isolates during 2000 - 2008, MLST method showed low discrimination power and the MLST method should not be applied to outbreak and epidemiological surveillance of Salmonella Paratyphi A. Currently, nationwide paratyphoid fever epidemics is caused by highly clonal isolates in China. As the time changes, these isolates also accumulate sporadic mutations.
authors.affiliation: National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Han
authors.forename: Hai-jian
authors.initials: HJ
authors.lastname: Zhou
authors.forename: Zhi-gang
authors.initials: ZG
authors.lastname: Cui
authors.forename: Peng-cheng
authors.initials: PC
authors.lastname: DU
authors.forename: Biao
authors.initials: B
authors.lastname: Kan
mesh_terms: D015373:Bacterial Typing Techniques; D002681:China; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D006801:Humans; D058885:Multilocus Sequence Typing; D010284:Paratyphoid Fever / Q000453:epidemiology / Q000382:microbiology*; D012482:Salmonella paratyphi A / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D017422:Sequence Analysis, DNA; D012703:Serotyping
chemical_list: D004269:DNA, Bacterial