title: Genotypic characterization of Staphylococcus aureus isolates from cases of keratitis and healthy conjunctival sacs.
abstract: OBJECTIVE
  Staphylococcus aureus is the predominant pathogen that causes keratitis, and the rate of occurrence of drug-resistant S. aureus is increasing. However, little is known about its clinical epidemiology in Japan. This study was designed to characterize the genotypes of methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) isolates from keratitis and healthy conjunctival sacs.
  
  
  METHODS
  Thirty keratitis isolates (19 MSSA and 11 MRSA) and 18 healthy conjunctival sac isolates (16 MSSA and 2 MRSA) obtained before cataract surgery were used. They were characterized by multilocus sequence typing. The prevalence of Panton-Valentine leukocidin was determined.
  
  
  RESULTS
  In multilocus sequence typing analysis, ST5 and ST764 (ST5 variant) were the most frequently identified sequence types in MRSA strains from both keratitis and healthy conjunctival sacs. ST188 was the most frequently identified sequence type in the 19 MSSA isolates from keratitis (4 isolates, 21.1%), but was only identified in 1 of the 16 commensal MSSA strains. ST8 was found to be predominant among the 16 commensal MSSA strains (5 isolates, 31.3%). None of the isolates had Panton-Valentine leukocidin genes.
  
  
  CONCLUSIONS
  MRSA isolates from keratitis and healthy conjunctival sacs may have similar genotypic characteristics, but certain clones occur more often among MSSA isolates from keratitis than among commensal MSSA strains. These results suggest that specific MSSA lineages that possess genotypic characteristics can more effectively cause keratitis.
authors.affiliation: Department of Ophthalmology, Ehime University Graduate School of Medicine, Toon, Japan.
authors.forename: Saeko
authors.initials: S
authors.lastname: Hayashi
authors.forename: Takashi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamaguchi
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Inoue
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ohashi
mesh_terms: D001427:Bacterial Toxins / Q000235:genetics; D003228:Conjunctiva / Q000382:microbiology*; D005098:Exotoxins / Q000235:genetics; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D007564:Japan / Q000453:epidemiology; D007634:Keratitis / Q000453:epidemiology / Q000382:microbiology*; D007956:Leukocidins / Q000235:genetics; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification; D058885:Multilocus Sequence Typing; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D001427:Bacterial Toxins; D005098:Exotoxins; D007956:Leukocidins; C078284:Panton-Valentine leukocidin