title: Characterization of Streptococcus pneumoniae ophthalmic, systemic & commensal isolates by pulsed-field gel electrophoresis & ribotyping.
abstract: OBJECTIVE
  Streptococcus pneumoniae is common in ocular and systemic infections and is a part of normal nasopharyngeal flora. Very few studies regarding genetic analysis of S. pneumoniae isolates causing eye infections are available. This study was undertaken to do pulse field gel electrophoresis (PFGE) analysis and ribotyping of S. pneumoniae isolates obtained from eye infections, systemic infections and nasopharyngeal flora.
  
  
  METHODS
  Sixty one well characterized S. pneumoniae isolates (38 from ophthalmic infections, 9 from systemic infections and 14 commensals) were characterized using PFGE of the whole genome after SmaI, restriction enzyme digestion and conventional ribotyping using Escherichia coli rRNA operon as the probe. Phylogenetic tree was drawn using unweighted pair group method analysis (UPGMA).
  
  
  RESULTS
  The 38 S. pneumoniae isolates from eye infections belonging to 15 serotypes were placed in to 11 PFGE types and 15 ribotypes. The 9 systemic isolates (7 seotypes) were distributed in 7 PFGE types and 6 ribotypes. The 14 commensal isolates were placed in 11 serotypes, 5 PFGE types and 6 ribotypes. Most of the PFGE types and ribotypes consisting of ocular isolates also contained systemic and commensal isolates.
  
  
  CONCLUSIONS
  Considerable genetic similarity was observed between the isolates from ocular and systemic infections and those colonized in nasopharynx. PFGE analysis could differentiate majority of the isolates according to site of infections. There was a considerable DNA polymorphism within the studied bacterial population.
authors.affiliation: Department of Ocular Microbiology, Dr RP Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Upendra K
authors.initials: UK
authors.lastname: Kar
authors.forename: Gita
authors.initials: G
authors.lastname: Satpathy
authors.forename: B K
authors.initials: BK
authors.lastname: Das
authors.forename: S K
authors.initials: SK
authors.lastname: Panda
mesh_terms: D015373:Bacterial Typing Techniques; D004247:DNA / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism; D016521:Electrophoresis, Gel, Pulsed-Field; D015817:Eye Infections / Q000382:microbiology*; D005798:Genes, Bacterial; D006801:Humans; D008957:Models, Genetic; D008970:Molecular Weight; D010802:Phylogeny; D011008:Pneumococcal Infections / Q000382:microbiology; D011110:Polymorphism, Genetic; D021521:Ribotyping / Q000379:methods*; D012984:Software; D013296:Streptococcus pneumoniae / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D004247:DNA