Hi Doc, I am a 60-year-old male fighting recurrent urinary tract infections since undergoing first radical surgery then hormomala therapy and finally raditaion therapy for prostate cancer. I have used Zanocin 400 under my doctor s advice. It appears that the medicine isn t working anymore. Maybe overuse has led to drug resistence. Can I try it one more time, and if yes, in what dosage and for how many days? Regards, Roy Calcutta