I invented the most effective saline flush for a chronic infection, but to be honest, I do not know how long you would have to wait
after surgery to do it, if ever, so I cannot recommend it to you. I believe your best alternative would be Dr. Murray Grossan's Hydropulse Irrigator, which you can research online, and if you get enough of the infected mucus out of your sinuses, the antibiotics may work better, unless the power and glory of evolution have made the microbes resistant.