Antimicrobial activity of selected aminoglycoside and fluoroquinolone eye drops against Staphylococcus aureus isolated from the conjunctiva of a bacterial conjunctivitis patient

A comparative in vitro study was conducted to ascertain the efficacy of 4 selected antibiotic eye drops against Staphylococcus aureus strain isolated from the conjunctiva of a patient diagnosed of bacterial conjunctivitis, and were assayed on the basis of the zone of inhibition. One and two drops volume of the test drugs were inoculated (administered). Results for average inhibition zone for 1 and 2 drops volume was Levofloxacin (26.88 mm), Ciprofloxacin (25.0 mm), Tobramycin (12.5 mm), Gentamicin (7.5 mm) and Levofloxacin (33.12 mm), Ciprofloxacin (30.6 mm), Tobramycin (19.3 mm) and Gentamicin (17.5 mm) respectively with two drops having higher effect than one for Levofloxacin˃ Ciprofloxacin˃ Tobramycin˃ Gentamicin by way of order of susceptibility. The difference in the average zones of inhibition produced by equal volumes of gentamicin and tobramycin and that between ciprofloxacin and levofloxacin both not statistically significant (p˃0.05). Fluoroquinolones showed greater zones of inhibition than the aminoglycosides significantly with levofloxacin more efficacious than ciprofloxacin. One drop prescription is thus recommended. However, if two drops must be prescribed perhaps due to severity of symptoms as the clinician may deem necessary, the drugs should be administered in divided doses. Antimicrobial sensitivity test should be conducted in cases of ocular bacterial infections caused by Staphylococcus aureus while treatment with fluoroquinolone especially levofloxacin eye drops as the first line treatment is also suggested.