In vitro susceptibilities to topical antibiotics of bacteria isolated fromthe surface of clinically symptomatic eyes

Background: The permanent change of resistance patterns of bacteria causing ocular infections makes repeat susceptibility testings against the most re cent clinical isolates mandatory. The aim of the present study was to asses s the in vitro susceptibility of ocular bacterial isolates of clinically sy mptomatic eyes admitted to the outpatient clinic of the eye department of a large central hospital to commonly used topical antibiotics. Methods: Ocul ar isolates (n = 454) were tested for their susceptibility to ofloxacin, ci profloxacin, norfloxacin, gentamicin, tobramycin, meomycin, bacitracin, ery thromycin, tetracycline and chloramphenicol. Results: All three tested fluo roquinolones were found to be very effective against gram-negative organism s but demonstrated some weakness against certain strains of gram-positive g erms, in particular coagulase-negative staphylococci and Streptococcus viri dans. These germs, however, were very susceptible to bacitracin and chloram phenicol. The relative overall in vitro efficacy was tin decreasing order): chloramphenicol, ciprofloxacin, ofloxacin, norfloxacin, bacitracin, tetrac ycline, neomycin, erythromycin, tobramycin and gentamicin. Conclusion: Chlo ramphenicol had the highest overall in vitro efficacy, but has potential le thal side effects. The fluoroquinolones were highly effective, especially b eing superior to the aminoglycosides tested, but no single antibiotic provi ded 100% coverage against all of the bacterial isolates that were tested. C opyright (C) 2001 S. Karger AG, Basel.