Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Botany Microbiology

Bacterial corneal ulcer is a vision threatening ocular infectious disease that remains the most aggressive and destructive pathogen invading the cornea. This study aims to describe the bacteriological pattern and risk factors of bacterial corneal ulcer. In addition, comparing the in vitro efficacy of commonly used synthetic antibiotics and some natural essential oils against resistant bacteria isolated from corneal ulcer. Corneal scrapings were taken under topical anesthesia from 200 patients. Patients were subjected to detailed investigations including age, gender, demographic features and predisposing risk factors. Isolation and identification of bacteria was performed using conventional microbiological methods. Antibiotic sensitivity was done by disc diffusion method. Essential oils were extracted from different parts of plants by steam distillation and were analyzed by GC/MS technique. Antibacterial activity of essential oils was done by the disk diffusion method. The minimum Inhibitory concentrations (MICs) of essential oils against S. aureus were determined by micro-dilution method. Trauma was the main predisposing factor of bacterial corneal ulcer. S. aureus was the predominant isolated organism from corneal ulcer. Antibiotic susceptibility pattern of bacterial isolates showed that the fourth-generation fluoroquinolones (gatifloxacin) was the most effective antibiotic and many isolates had high resistance rate against most of antibiotics. Seven selected essential oils showed significant activity against most of the bacteria tested. Clove oil showed high activity against all tested bacterial species with highest sensitivity rate (97.5 %) and low MIC values against S. aureus

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