title: Genetic diversity of Streptococcus suis isolated from three pig farms of China obtained by acquiring antibiotic resistance genes.
abstract: BACKGROUND
  Acquiring antibiotic resistance genes may change an organism's genetic characteristics and the effect of antibiotics, resulting in a rapid transmission of microbial pathogens. The objectives of this experiment were to identify the features of Streptococcus suis (S. suis) isolated from three pig farms in China which are geographically isolated.
  
  
  RESULTS
  Among the isolates, 56.52% were sequence type 7 (ST7), followed by ST1 (26.09%), indicating that ST7 prevails in China, as revealed by multi-locus sequence typing (MLST). Statistical analysis indicated an association between geography, sequence types and antibiotic resistance genotypes. 66.67% of the isolates in Sichuan province presented a (ermB(-) + mefA(-) + tetO(-) + tetM(-)) + ST7 type. The tetM(+) +ST7 type was the most prevalent in Jiangsu province, whereas the strains from Hebei province had a phenotype ermB(+) +tetO(+) +ST1 (63.64%). Pulsed-field gel electrophoresis (PGFE) pattern A2 with 100% similarity reflected the clonal dissemination between Sichuan and Jiangsu provinces. Strains carrying or not carrying antibiotic resistance genes presented different PFGE patterns in Hebei province.
  
  
  CONCLUSIONS
  ST7 is widespread in many regions of China and a clonal dissemination occurred between Sichuan and Jiangsu provinces in diseased pigs. However, ST1 strains with macrolide and tetracycline resistance (ermB(+) +tetO(+) +ST1) isolated from a farm in Hebei province demonstrated that the genetic diversity was contributed by horizontal acquiring of ermB and tetO carrying elements.
authors: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, P.R. China.
authors: Jinhu
authors: J
authors: Huang
authors: Kexin
authors: K
authors: Shang
authors: Jam
authors: J
authors: Kashif
authors: Liping
authors: L
authors: Wang
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D002681:China; D004352:Drug Resistance, Microbial / Q000235:genetics*; D005798:Genes, Bacterial; D014644:Genetic Variation; D058885:Multilocus Sequence Typing; D013290:Streptococcal Infections / Q000382:microbiology*; D017011:Streptococcus suis / Q000235:genetics* / Q000302:isolation & purification; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins
keywords: MLST; PFGE; Streptococcus suis; antibiotic resistance; pigs