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C. R. Alabiad, D. Miller, J. Schiffman, J. L. Davis; Antimicrobial Sensitivity Profiles of Ocular and Nasal Flora in Patients Undergoing Intravitreal Injections. Invest. Ophthalmol. Vis. Sci. 2009;50(13):297.
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Fluoroquinolone resistant organisms are emerging as prevalent intraocular pathogens. Topical fourth generation fluoroquinolones are often used as prophylaxis after intravitreal injections and intraocular surgery.The objectives of this study are to identify bacterial isolates in the conjunctiva and nose and to determine if frequent exposure to topical fluoroquinolones increases antimicrobial resistance in these isolates.
Patients aged 18 and older undergoing intravitreal injection for any reason were eligible for inclusion in this prospective study. A sterile swab was used to obtain specimens from both nares and both conjunctival fornices prior to ocular preparation including povidone iodine and injection. Each of the four culture swabs were plated on blood and chocolate agar plates and analyzed by the microbiology lab. The charts of each patient were reviewed. All patients had a history of topical prophylaxis with fluoroquinolones after each previous injection. Data was analyzed using the chi square test.
208 conjunctival and nasal specimens were cultured from 104 patients. The patient population was comprised of 55 women and 49 men (mean age + SD; 73 + 14.4 years). Patients had an average of 2.1 previous injections in the right eye (range, SD; 0-11, + 2.9) and 2.7 previous injections in the left eye (range, SD; 0-39, + 5.5). The main indication for intravitreal injection was wet age related macular degeneration (n=57 or 54.8%). Staphylococcus epidermidis was the most frequently isolated organism in both the nose and conjunctiva (26 conjunctiva and 137 nares) with five specimens having more than one isolate. Fluoroquinolone resistance patterns among Staphylcoccus epidermis isolates in the conjunctiva were as follows: Ciprofloxacin 32.3% (10 of 31 isolates), Gatifloxacin 35.5% (11 of 31 isolates), Moxifloxacin 29.0% (9 of 31 isolates). Fluoroquinolone resistance patterns among Staphylococcus epidermis isolates in the nose were as follows: Ciprofloxacin 38.2% (60 of 157 isolates), Gatifloxacin 28.7% (45 of 157 isolates), Moxifloxacin 28.0% (44 of 157 isolates). Chi square analysis of fluoroquinolone resistant Staphylococcus epidermidis isolates stratified according to number of injections (none, 1 to 4, and greater than 5 injections) revealed a p>0.05.
There does not appear to be a correlation between the number of exposures to topical fluoroquinolones and resistance to fluoroquinolones in nasal and conjunctival flora. The high prevalence of fluoroquinolone resistance among flora in this study suggests that topical fluoroquinolones may not be the ideal choice for post injection prophylaxis.
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