title: Genotyping of Salmonella enterica serovar Typhi strains isolated from 1959 to 2006 in China and analysis of genetic diversity by genomic microarray.
abstract: OBJECTIVE
  To determine the genotype of Salmonella enterica serovar Typhi (S. Typhi) strains in China and analyze their genetic diversity.
  
  
  METHODS
  We collected S. Typhi strains from 1959 to 2006 in five highly endemic Chinese provinces and chose 40 representative strains. Multilocus sequence typing was used to determine the genotypes or sequence types (ST) and microarray-based comparative genomic hybridization (M-CGH) to investigate the differences in gene content among these strains.
  
  
  RESULTS
  Forty representative S. Typhi strains belonged to 4 sequence types (ST1, ST2, ST890, and ST892). The predominant S. Typhi genotype (31/40) was ST2 and it had a diverse geographic distribution. We discovered two novel STs - ST890 and ST892. M-CGH showed that 69 genes in these two novel STs were divergent from S. Typhi Ty2, which belongs to ST1. In addition, 5 representative Typhi strains of ST2 isolated from Guizhou province showed differences in divergent genes.
  
  
  CONCLUSIONS
  We determined two novel sequence types, ST890 and ST892, and found that ST2 was the most prevalent genotype of S. Typhi in China. Genetic diversity was present even within a highly clonal bacterial population.
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Basic Medicine and Medical Technology, Jiangsu University, Xuefu road 301, Zhenjiang, China.
authors.forename: Haifang
authors.initials: H
authors.lastname: Zhang
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Zhang
authors.forename: Meiying
authors.initials: M
authors.lastname: Yan
authors.forename: Bo
authors.initials: B
authors.lastname: Pang
authors.forename: Biao
authors.initials: B
authors.lastname: Kan
authors.forename: Huaxi
authors.initials: H
authors.lastname: Xu
authors.forename: Xinxiang
authors.initials: X
authors.lastname: Huang
mesh_terms: D000483:Alleles; D002681:China / Q000453:epidemiology; D004269:DNA, Bacterial; D014644:Genetic Variation / Q000235:genetics; D005838:Genotype; D006801:Humans; D058885:Multilocus Sequence Typing; D020411:Oligonucleotide Array Sequence Analysis; D012485:Salmonella typhi / Q000235:genetics*; D014435:Typhoid Fever / Q000453:epidemiology / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial