title: lukSF-PV in Staphylococcus aureus keratitis isolates and association with clinical outcome.
abstract: OBJECTIVE
  To determine the prevalence, genetic diversity, and clinical relevance of the lukSF-PV gene, encoding the bacterial toxin Panton-Valentine leukocidin, in Staphylococcus aureus isolates from cases of bacterial keratitis in the United Kingdom.
  
  
  METHODS
  Multiplex PCRs investigating carriage of lukSF-PV and mecA were performed on S. aureus isolates from patients. The lukSF-PV operon was sequenced to investigate its diversity, and multilocus sequence typing to test for a clonal relationship between lukSF-PV isolates. Antimicrobial minimum inhibitory concentrations (MICs) and clinical outcome data were compared for isolates characterized as lukSF-PV+ve, mecA+ve, and lukSF-PV/mecA-ve.
  
  
  RESULTS
  Of 95 isolates, 9 (9.5%) were lukSF-PV+ve, 9 (9.5%) mecA+ve, and 1 was positive for both. Five single nucleotide polymorphisms were found in lukSF-PV genes of seven strains. There was no significant difference between the MICs of lukSF-PV/mecA-ve and lukSF-PV+ve isolates to the antimicrobials tested, except for tigecycline (P < 0.05). The mecA+ve isolates had significantly higher mean MICs to meropenem and fluoroquinolones (P < 0.05). There were nonsignificant trends for healing and treatment times, ulcer and scar size, and overall clinical score to be greater in the lukSF-PV+ve group (P < 0.05). The proportion of patients, however, who required surgery was significantly greater among patients with lukSF-PV+ve isolates with an odds ratio of 7.8 (95% CI 1-42, P = 0.018) for patients requiring surgery.
  
  
  CONCLUSIONS
  lukSF-PV+ve isolates were associated with a trend to worse clinical outcome and more surgical interventions, with an effect unrelated to MICs. This suggests that lukSF-PV may be an important virulence factor in S. aureus-associated keratitis.
authors.affiliation: St Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, United Kingdom. hsueke@gmail.com
authors.forename: Henri
authors.initials: H
authors.lastname: Sueke
authors.forename: Jayendra
authors.initials: J
authors.lastname: Shankar
authors.forename: Timothy
authors.initials: T
authors.lastname: Neal
authors.forename: Craig
authors.initials: C
authors.lastname: Winstanley
authors.forename: Stephen
authors.initials: S
authors.lastname: Tuft
authors.forename: Rosanna
authors.initials: R
authors.lastname: Coates
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: Horsburgh
authors.forename: Stephen
authors.initials: S
authors.lastname: Kaye
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001427:Bacterial Toxins / Q000235:genetics* / Q000378:metabolism; D003320:Corneal Ulcer / Q000188:drug therapy / Q000382:microbiology*; D005098:Exotoxins / Q000235:genetics* / Q000378:metabolism; D005260:Female; D024841:Fluoroquinolones / Q000627:therapeutic use; D006801:Humans; D007956:Leukocidins / Q000235:genetics* / Q000378:metabolism; D008297:Male; D046915:Penicillin-Binding Proteins; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D006113:United Kingdom; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D005098:Exotoxins; D024841:Fluoroquinolones; D007956:Leukocidins; C078284:Panton-Valentine leukocidin; D046915:Penicillin-Binding Proteins; C108483:leukocidin S-component protein, Staphylococcus; C487789:mecA protein, Staphylococcus aureus; C074300:LukF protein, Staphylococcus aureus
keywords: Panton-Valentine leukocidin; Staphylococcus aureus keratitis; keratitis