Microbar Powder is a sterile, preservative free, powdered form of the drug gentamicin sulfate. It is used to treat a variety of bacterial infections, including those that affect the eyes, ears, skin, and urinary tract. The powder is administered directly into the affected area via injection or topical application. Gentamicin sulfate is an antibiotic that works by inhibiting the growth of bacteria. It is commonly used to treat eye infections, ear infections, and skin infections.