Tobradex (tobramycin and dexamethasone) ophthalmic ointment given for eye rednes,swelling,oozing yellow,drynes-no bacterial infection found in skin scraping-why then give antibiotic?

Culture ?: Tobradex (tobramycin and dexamethasone) is a good treatment for severe redness caused by bacterial conjunctivitis, especially those caused by gram negative bacteria. If an eye scraping is done with culture and no bacteria are cultured, the irritation may be due to viral or allergic issues, that could be complicated by bacterial superinfection. Tobradex (tobramycin and dexamethasone) is a good 1st line, followed by specific therapy based on sensitivities