In-vitro Efficacy of Antimicrobial Agents Used in the Treatment of Bacterial Eye Infections in Ibadan, Nigeria

Failure to cure eye infections, and reduced potency in topical antimicrobials had been observed in South Western Nigeria, this study sought to evaluate in vitro, the efficacy of antimicrobial agents in the treatment of ocular infections. A total of 46 ocular bacterial isolates were recovered from the diagnostic laboratory of the University College Hospital, Ibadan, from conjunctival swabs of patients having underlying eye diseases (Cataracts, glaucoma and esotrapia), and from patients presenting with other symptoms of eye infections. The pathogens incriminated were Staphylococcus aureus (73.5%), Coagulase negative Staphylococci (13.3%), Klebsiella species (10.3%), and Pseudomonas aeruginosa (2.0%). Disc diffusion tests (Bauer-Kirby method) were carried out using ciprofloxacin, gentamicin, chloramphenicol, erythromycin, augmentin, cefuroxime and levofloxacin. Broth dilution techniques were thereafter performed using gentamicin, chloramphenicol and ciprofloxacin. The microlideerythromycin was 63.0% efficacious, augmentin and cefuroxime showed 71.1% and 76% efficacy. Minimum inhibitory concentrations (MIC) of commonly used topical antibiotics however showed different levels of resistance. Resistance to the aminoglycosides was marked, yielding 53.4% with MIC50= 8, MIC90 > 256, Resistance to chloramphenicol was even more marked 69.6% with MIC50= 16, MIC90= 64, the fluoroquinolones showed high efficacylevofloxacin and ciprofloxacin showed 93.4% and 82.6% susceptibility respectively with MIC50 < 0.5, though slightly demonstrable resistance was observed (MIC90= 8). The study thus recommends the discontinuation of empirical therapy by physicians in order to stem the tide of resistance; it justifies the inclusion of the fluoroquinolones in susceptibility testing of ocular bacterial isolates, and its first line of choice if