Maybe a mix of Colloidal Silver and amoxicillin. One of the sponsors of curezone is Utopia-Silver . They've got a special deal for curezone members for first time buyers -- phone in calls only -- buy one -- get one free. I think it's for any size. For a kidney infection, you probably need to drink several ounces (3-4) several times a day. You can also make it yourself quite easily, too. Utopia has a CS generator for sell and the silver wires too. Or if you're a DIYer, you can just get the silver wires, some alligator clips, 9volt batteries and battery connectors and make your own. That's what I ended up doing and I'm now churning out home made CS a quart at a time. I just recently brewed up a little over a half a gallon for my brother.
But, other drugs for kidney infections include augmentin -- which is pretty strong, and septrin. Sulfa drugs (Septrin is a sulfa drug) were routinely prescribed for kidney and bladder infections before cipro came along. As long as you're not allergic to sulfa drugs.