title: Changes in ocular flora in eyes exposed to ophthalmic antibiotics.
abstract: OBJECTIVE
  To determine changes in ocular flora in individuals repeatedly exposed to topical macrolide or fluoroquinolone antibiotics.
  
  
  METHODS
  Prospective, controlled, longitudinal study with 1-year follow-up.
  
  
  METHODS
  Forty-eight eyes of 24 patients undergoing serial unilateral intravitreal injection for choroidal neovascularization.
  
  
  METHODS
  Patients received 4 consecutive monthly unilateral intravitreal injections and were then treated as needed. Each patient was randomized to 1 of 4 antibiotics (azithromycin 1%, gatifloxacin 0.3%, moxifloxacin 0.5%, ofloxacin 0.3%) and used only their assigned antibiotic for 4 days after each injection. Conjunctival cultures of the treated eye and untreated fellow eye (control) were taken at baseline and before each injection. All bacterial isolates were tested for antibiotic susceptibility to 16 different antibiotics using the Kirby-Bauer disc diffusion technique.
  
  
  METHODS
  Changes in bacteria composition of the conjunctiva over time.
  
  
  RESULTS
  In azithromycin-treated eyes, Staphylococcus epidermidis and Staphylococcus aureus accounted for 54.5% and 18.2% of cultured isolates, respectively, at baseline and 90.9% (P<0.01) and 4.5% (P<0.01), respectively, after azithromycin exposure. In fluoroquinolone-treated eyes, 45.7% and 6.5% of cultured isolates at baseline were S epidermidis and S aureus, respectively, but these percentages increased to 63.4% (P<0.03) and 13% (P = 0.24), respectively, after fluoroquinolone exposure. In contrast, the percentage of gram-negative species decreased from 8.7% at baseline to 1.6% (P<0.05) in fluoroquinolone-treated eyes. The percentage of S epidermidis isolated from azithromycin-treated eyes was significantly greater when compared with fellow control eyes (P<0.01) or fluoroquinolone-treated eyes (P<0.01).
  
  
  CONCLUSIONS
  The percentage of S epidermidis isolated from the conjunctival surface significantly increases after repeated exposure to azithromycin and to a lesser degree fluoroquinolone antibiotics at the expense of other commensal flora.
  
  
  BACKGROUND
  The author(s) have no proprietary or commercial interest in any materials discussed in this article.
authors: Department of Ophthalmology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
authors: Sarita B
authors: SB
authors: Dave
authors: Hassanain S
authors: HS
authors: Toma
authors: Stephen J
authors: SJ
authors: Kim
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001372:Aza Compounds / Q000627:therapeutic use; D017963:Azithromycin / Q000627:therapeutic use; D001419:Bacteria / Q000187:drug effects / Q000302:isolation & purification*; D020256:Choroidal Neovascularization / Q000188:drug therapy* / Q000382:microbiology; D003228:Conjunctiva / Q000382:microbiology*; D024881:Drug Resistance, Bacterial; D024841:Fluoroquinolones / Q000627:therapeutic use; D000077734:Gatifloxacin; D006801:Humans; D058449:Intravitreal Injections; D008137:Longitudinal Studies; D000077266:Moxifloxacin; D015242:Ofloxacin / Q000627:therapeutic use; D011804:Quinolines / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D001372:Aza Compounds; D024841:Fluoroquinolones; D011804:Quinolines; D017963:Azithromycin; D015242:Ofloxacin; D000077734:Gatifloxacin; D000077266:Moxifloxacin