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2010 OMIG, Abstract 12

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Topical fluoroquinolone use as a risk factor for in vitro fluoroquinolone resistance in ocular cultures
N.R. Acharya1, R.E. Fintelmann1, E.N. Hoskins1, J.D. Keenan1, B.D. Gaynor1, V. Cevallos1, T.M. Lietman1,2
1F.I. Proctor Foundation and Dept. of Ophthalmology, University of California, San Francisco, CA, 2Dept. of Epidemiology & Biostatistics, University of California, San Francisco, CA

Purpose:  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 Staphylococcus aureus at the F.I. Proctor Foundation microbiology laboratory from January 1, 2005 to December 31, 2008. The medical records of patients with positive Staphylococcus aureus cultures were reviewed to determine topical or systemic fluoroquinolone use within the 3 months prior to culture. Fisher's 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 Staphylococcus aureus cultures, 41 (20.5%) were resistant to ciprofloxacin, moxifloxacin and gatifloxacin.  Fluoroquinolone-resistant S. aureus isolates were from older patients (mean 65.5 years; SD=25.0) compared to fluoroquinolone-susceptible isolates (mean 52.1 years; SD=22.1), P=0.003. Use of fluoroquinolones in the preceding 3 months was more frequent in resistant isolates (29%) compared to susceptible isolates (11%), P=0.005, as was recent hospitalization (22% of resistant isolates, 0% of susceptible isolates, P<0.001). In the multivariate regression analysis, topical fluoroquinolone use within 3 months was a significant predictor of fluoroquinolone resistance (P=0.046), along with age, systemic immunosuppression and topical fluoroquinolone use between 3 and 6 months.
Conclusions:  Recent topical fluoroquinolone use is significantly associated with fluoroquinolone resistance in S. aureus isolates from ocular cultures.

Disclosure Code: N; Grant funding: Research to Prevent Blindness

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