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D. Miller, J. Diniz, M. Diaz, E. Perez, H.W. Flynn, Jr, E.C. Alfonso; In vitro Comparison of Moxifloxacin, Gatifloxacin, Gentamicin and Tobramycin Against Ciprofloxacin Resistant Gram positive and Gram Negative Ocular Pathogens. . Invest. Ophthalmol. Vis. Sci. 2004;45(13):4923.
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Purpose: Because the fourth generation fluoroquinolones target both DNA gryrase and topiosomerase IV, they are predicted to provide improved coverage for both gram positive and gram–negative ocular pathogens. We compared the in vitro efficacy of two new fluoroquinolones, moxifloxacin and gatifloxacin versus two older aminoglycosides, gentamicin and tobramycin to provide enhanced coverage for selected groups of ciprofloxacin resistant gram positive and gram–negative pathogens recovered from ocular infections at our Institute from1990–2003. Methods: E tests and disk diffusion methods were employed to determine in vitro susceptibility of ciprofloxacin, moxifloxacin, gatifloxacin, gentamicin and tobramycin against 256 gram positive and 110 gram negative ocular isolates. 40% of the isolates were from vitreous and ac fluids, 28% from conjunctiva 23% from cornea and the remainder (8%) from orbit and lacrimal apparatus. Isolate frequency included: CNS, N=128, S. aureus, N=79 , Streptococci, N=39, Bacillus species, N=10, P. aeruginosa, N= 34, H. influenzae, N=22, and GNB, other (54). Results: Percent susceptible in descending order for gram–positive pathogens were gentamicin (79%), gatifloxacin and moxifloxacin (76%) and ciprofloxacin (65%). The order for gram–negative isolates was tobramycin and gatifloxacin (86%), ciprofloxacin, and moxifloxacin (83%). Gram–positive pathogens were twice as likely compared to gram–negative pathogens to be ciprofloxacin resistant (p. = 0.000, 95 CI). Aminoglycosides provided coverage for 67% of the ciprofloxacin resistant gram–positive isolates and 37%of the ciprofloxacin resistant gram–negative isolates. Moxifloxacin provided in vitro coverage for 36% of the ciprofloxacin resistant gram–positive isolates and 16% of the ciprofloxacin resistant gram–negative isolates. Coverage for gatifloxacin was 33% and 26% respectively. At least 60% of the gram–positive isolates and 70% of the gram–negative isolates resistant to ciprofloxacin displayed cross–resistance to gatifloxacin and moxifloxacin. Conclusions: The in vitro susceptibility for the aminoglycosides and the newer fluoroquinolones were comparable for this group of ocular pathogens. Gentamicin and Tobramycin offered broader coverage for ciprofloxacin resistant isolates.
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