Try cranberry juice capsules. One daily. It works well for some. There is also a formula with a dextrose molecule. Again one daily. It is well worth the trial. The rational for using it is to prevent E. coli from invading bladder wall.
A sensitivity report on your urine culture may show the bacteria are resistant to Keflex. Daily macrobid , from my experience resulted in a interesting overgrowth of bacteria that are often cultured out of Foley catheter bags, NO THANK YOU. The cranberry capsules have been remarkably beneficial and may work for others.