title: Topical fluoroquinolone use as a risk factor for in vitro fluoroquinolone resistance in ocular cultures.
abstract: OBJECTIVE
  To determine whether recent use of topical fluoroquinolones is a risk factor for in vitro fluoroquinolone resistance in Staphylococcus aureus ocular isolates.
  
  
  METHODS
  Disk diffusion susceptibility testing for ciprofloxacin, moxifloxacin, and gatifloxacin was performed for all ocular isolates of S aureus at the Francis I. Proctor Foundation microbiology laboratory from January 1, 2005, to December 31, 2008. The medical records of patients with positive S aureus cultures were reviewed to determine topical or systemic fluoroquinolone use within the 3 months prior to culture. The Fisher exact test was used to compare the proportion of patients who used topical fluoroquinolones in the past 3 months among fluoroquinolone-sensitive and -resistant cases. Logistic regression was used to determine risk factors for fluoroquinolone resistance.
  
  
  RESULTS
  Of 200 S aureus cultures, 41 were resistant to ciprofloxacin, moxifloxacin, and gatifloxacin (20.5%). Fluoroquinolone-resistant S aureus isolates were from older patients (mean [SD] age, 65.5 [25.0] years) compared with fluoroquinolone-susceptible isolates (mean [SD] patient age, 52.1 [22.1] years) (P = .003). Use of fluoroquinolones within the 3 months before testing was more frequent in resistant isolates (29%) than in susceptible isolates (11%) (P = .005), as was recent hospitalization (22% of resistant isolates, 0% of susceptible isolates) (P < .001). In the multivariate regression analysis, topical fluoroquinolone use within 3 months was a significant predictor of fluoroquinolone resistance (P = .046), along with age, systemic immunosuppression, and topical fluoroquinolone use between 3 and 6 months before testing.
  
  
  CONCLUSIONS
  Recent topical fluoroquinolone use is significantly associated with fluoroquinolone resistance in S aureus isolates from ocular cultures.
authors.affiliation: Francis I. Proctor Foundation for Research in Ophthalmology, University of California-San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143-0412, USA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Fintelmann
authors.forename: Eliza N
authors.initials: EN
authors.lastname: Hoskins
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Lietman
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Keenan
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Gaynor
authors.forename: Vicky
authors.initials: V
authors.lastname: Cevallos
authors.forename: Nisha R
authors.initials: NR
authors.lastname: Acharya
mesh_terms: D000287:Administration, Topical; D000368:Aged; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000494:pharmacology; D001372:Aza Compounds / Q000008:administration & dosage / Q000494:pharmacology; D002939:Ciprofloxacin / Q000008:administration & dosage / Q000494:pharmacology; D052978:Disk Diffusion Antimicrobial Tests; D024901:Drug Resistance, Multiple, Bacterial; D015818:Eye Infections, Bacterial / Q000188:drug therapy / Q000382:microbiology*; D005260:Female; D024841:Fluoroquinolones / Q000008:administration & dosage* / Q000494:pharmacology; D000077734:Gatifloxacin; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D000077266:Moxifloxacin; D011804:Quinolines / Q000008:administration & dosage / Q000494:pharmacology; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D001372:Aza Compounds; D024841:Fluoroquinolones; D011804:Quinolines; D002939:Ciprofloxacin; D000077734:Gatifloxacin; D000077266:Moxifloxacin